Regulatory Guide 1.132

Site Investigations for Foundations of Nuclear Power Plants
	ML13350A266
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Issue date:	09/30/1977
From:	; NRC/OSD
To:	;
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	RG-1.132
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U.S. NUCLEAR REGULATORY COMMISSION

September 1977

0-0

)REGULATORY

GUIDE

OFFICE OF STANDARDS DEVELOPMENT

REGULATORY GUIDE 1.132 SITE INVESTIGATIONS FOR FOUNDATIONS

OF NUCLEAR POWER PLANTS

A. INTRODUCTION

programs as well as specific guidance for conducting Appendix A, "Seismic and Geologic Siting Criteria subsurface investigations, the spacing and depth of for Nuclear Po%%er Plants." to 10 CFR Part 100,

borings, and sampling. Appendix A provides defini-

"'Reactor Site Criteria," establishes requirements for lions for some of the terms used in this guide. These conducting site investigations to permit an evaluation terms are identified in the text by anasterisk. Appen- of the site and to provide information needed for dix B tabulates methods of conducting subsurface in- seismic response analyses and engineering design. Re- vestigations. and Appendix C gives cfiteria for the quirements include the development of geologic in- spacing and depth of borings.for.safety-related struc- lures in regions of favorable or-uniform conditions.

formation relevant to the stratigraphy. lithology.

eeecsLtdih.tx n geologic history, and structural geology of the site References cited in'.he text and appendices are listed and the evaluation of the engineering properties of in Appendix D.., Appendix E contains a subsurface materials, bibliogr.aphical.liting oLreated material.

Safety-related site characteristics are identified in

.

DISCUSSION

detail in Rcgulatory Guide 1.70. "Standard For- l.,Cenera.,

mat and Content of Safety Analysis Reports for Sii'6i'inve.itigations for nuclear power plants are

Nuclear Power Plants."

Regulatory' Guide 4.7.

e .*sne sar* to determine the geotechnical charac-

"General Site Suitability Criteria for Nuclear Poyer ,;eristics of a site that affect the design, performance, Stations," discusses major site characteristics thi'a-

,and afety of plants. The investigations produce the feet site suitabilitv.

....

.

information needed to define the overall site geology This guide describes programs of sitiinv stihtions that is necessary for an understanding of subsurface that would normally meet the needifor evalua[ing conditions and for identifying potential geologic and the safety of the site from the standpý'int of*hfe per- earthquake hazards that may exist at the site.

formance of foundations and earthwor'46&er most Investigations for hazards such as faulting.

anticipated loading conditions, including earth- landslides, cavernous rocks, ground subsidence, and quakes. It also describe.6 ite investigations required soil liquefaction are especially important.

to evaluate geotec hlical,*laramcters needed, for engineering anffy1.i$ Ma, deslgn. The site investiga- Site investigations also provide information needed tions discus ind in*Us Nide are applicable to both to define local foundation and groundwater condi- S'

t ions as well as the geotechnical parameters needed land uandi.cfflo~re si;.

This guide does not deal with tosa hydr Ai.i lions, except for groundwater for engineering analysis and design of foundations icasu _"Its, nor does . it discuss geophysical and earthworks. Geotechnical parameters needed for

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analysis and design include, but are not limited to.

IV

those used to evaluate the bearing capacity o' foun- This guide provides general guidance and recom- dation materials, lateral earth pressures against walls.

mend'ations for developing site-specific investigation the stability of cuts and slopes in soil and rock. the ef- USNRC REGULATORY GUIDES

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fect of earthquake-induced motions through underly- ing deposits on the response of soils and structures (including the potential for inducing liquefaction in soils). and those needed to estimate the expected set- tement of structures. Geotechnical parameters arc also needed for analysis and design of plant area fills, structural fills, backfills. and earth and rockfill dams.

dikes, and other water retention or flood protection structures.

Site information needed to assess the functional in.

tegrity of foundations with respect to geologic and geotechnical considerations include:

a. The geologic origin, types, thicknesses. se.

quence. depth. location, and areal extent of soil ant rock strata and the degree and extent of theii weathering:

h. Orientation and characteristics of foliations bedding. jointing, a !d faulting in rock, c. Groundwater c,,nditions:

d. The static and dynamic engineering proper ties of subsurface materials:

e. Information regarding the results of in vestigations of' adverse geological conditions such a, cavities, joints, faults. fissures. or unfavorable soi conditions:

f. Information related to man's activities such a withdrawal of fluids from or addition of fluids to th subsurface, extraction of minerals, or loading effect of dams or reservoirs: and g. Information detailing any other geologic con dition discovered at the site that may affect the desig or performance of the plant or the location of struc tures.

2. Reconnaissance Investigations and Literatur Reviews Planning of subsurface investigations and the ii terpretation of data require thorough understandir of the general geology of the site. This can be ol rained by a reveiw. either preceding or accompanyir the subsurface investigation, of available documei tary materials and results of previous investigation In most cases, a preliminary study of the site geolol can be done by review of existing current an historical documentary materials and by study aerial photographs and other remote sensir imagery. Possible sources of current and historic documentary information may include:

a. Geology and engineering departments State and loce! universities, b. State government agencies such as the State

,*

Geological Survey, c. U.S. Government agencies such as the U.S.

Geological Survey and the U.S. Army Corps of Engineers.

d. Topographic maps.

e. Geologic and geophysical maps,

"

f. Engineering geologic maps.

g. Soil survey maps.

"

Ih. Geologic reports and other geological literature, i. Geotechnical reports and other geotechnical literature.

j. Well records and water supply reports.

k. Oil well records.

I. Hydrologic maps.

m. Hydrologic and tidal data and flood records, s

n. Climate and rainfall records.

o. Mining history, old mine plans. and sub- sidence records.

C

p. Seismic data and historical earthquake s

records.

q. Newspaper records of landslides, floods.

-

earthquakes. subsidence, and other events oflgeologic n

or geotechnical significance, r. Records of performance of other structures in the vicinity, and e

s. Personal communication with local inhabi- tants and local professionals.

Special or unusual problems such as swelling soils Ig and shales (subject to large volume changes with b-

changes in moisture), occurrences of gas, cavities in Ig soluble rocks, subsidence caused by mining or pump- I-

ing ofwater. gas. or oil from wells, and possible uplift s.

due to pressurization from pumping of water, gas, or d

oil into the subsurface may require consultation with

)d individuals, institutions, or firms having experience of in the area with such problems.

al The site investigation includes detailed surface ex- ploration of the immediate site area and adjacent en- virons. Further detailed surface exploration also may of be required in areas remote to the immediate plant site to complete the geologic evaluation of the site or

1.132-2

0I

a

-- M

to conduct detailed investigations of surface faulting or other features. Surface exploration needed for the assessment of the site geology is site dependent and may be carried out with the use of any appropriate combination of geological, geophysical (seismic refraction), or engineering techniques. Normally this includes the following:

a. Detailed mapping of topographic, hydrologic, and surface geologic features, as ap- propriate for the particular site conditions, with scales and contour intervals suitable for analysis and engineering design. For offshore sites, coastal sites, or sites located near lakes or rivers this includes topography and detailed hydrographi, surveys to the extent that they are needed for site evaluation and engineering design.

b. Detailed geologic interpretations of aerial photographs and other remote-sensing imagery, as appropriate for the particular site conditions, to as- sist in identifying rock outcrops, soil conditions, evidence of past landslides or soil liquefaction, faults, fracture traces, and lineaments.

c. Detailed onsite mapping of local engineering geology and soils.

d. Mapping of surface water features such as rivers, streams, or lakes and local surface drainage channels, ponds, springs, and sinks at the site.

3. Groundwater Investigations Knowledge of groundwater conditions. their relationship to surface waters, and variations as- sociated with seasons or tides is needed for founda- tion analyses. Groundwater conditions should be observed in borings at the time they are made:

however, for engineering applications, such data must be supplemented by groundwater observations made by means of properly installed wells or piezometers* that are read at regular intervals from the time of their installation at least through the con- struction period. The U.S. Army Corps of Engineers'

manual on groundwater and pore pressure observa- tions in embuinkment dams and their foundations (Ref. I) provides guidance on acceptable mrthods for the installation and maintenance of piezometer and observation well* instrumentation. Piezometer or well installations should be made in as many loca- tions as needed to define groundwater conditions.

When the possibility of perched groundwater tables or artesian pressures is indicated by borings or other evidence, piezometer installation should be made to measure each piezometric level independently. Care should be taken in the design and installation of piezometers to prevent hydraulic communication between aquifers. The occurrence of artesian pressure in borings should be noted on boring logs. and their heads should be measured and logged.

Where construction dewatering is required, piezometers or observation wells should be used dur- ing construction to monitor the groundwater surface and pore pressures beneath the excavation and in the adjacent ground. The guide does not cover groundwater monitoring needed during construction in plants that have permanent dewatering systems in- corporated in their design.

4. Subsurface Investigations a. General The appropriate depth, layout, spacing. and sampl- ing requirements for subsurface investigations are dictated by the foundation requirements and by the complexity of the subsurface conditions. Methods of conducting subsurface investigations are tabulated in Appendix B, and criteria for the spacing and depth of borings for safety-related structures, where favorable or uniform geologic conditions exist. are given in Ap- pendix C.

Subsurface explorations for less critical founda- tions of power plants should be carried out with spac- ing and depth of penetration as necessary to define the general geologic and foundation conditions of the site. Subsurface investigations in areas remote from plant foundations may be needed to complete the geologic description of the site and confirm geologic and foundation conditions and should also be carefully planned.

Subsurface conditions may be considered favorable or uniform if the geologic and stratigraphic features to be defined can be correlated from one bor- ing or sounding* location to the next with relatively smooth variations in thicknesses or properties of the geologic units. An occasional anomaly or a limited number of unexpected lateral variations may occur.

Uniform conditions permit the maximum spacing of borings for adequate definition of the subsurface con- ditions at the site.

Occasionally soil or rock deposits may be en- countered in which the deposition patterns are so complex that only the major stratigraphic boundaries are correlatable, and material types or properties may vary within major geologic units in an apparently random manner from one boring to another. The number and distribution of borings needed for these conditions will exceed those indicated in Appendix C

and are determined by the degree of resolution needed in the definition of foundation properties.

1.132-3

The cumulative thicknesses of the various material types, their degree of variability, and ranges of the material properties must be defined.

If there is evidence suggesting the presence of local adverse anomalies or discontinuities such as cavities.

sinkholes, fissures, faults, brecciation. and lenses or pockets of unsuitable material, supplementary bor- ings or soundings at a spacing small enough to detect and delineate these features are needed. It is impor- tant that these borings should penetrate all suspect zones or extend to depths below which their presence would not influence the safety of the structures.

Geophysical investigations may be used to supple- ment the boring and sounding program.

in planning the exploration program for a site, consideration should also be given to the possibility that the locations of structures may be changed, and that such changes may require additional exploration to adequately define subsurface conditions at the final locations.

The location and spacing of borings, soundings.

and exploratory excavations should be chosen carefully to adequately define subsurface conditions.

A uniform grid may not provide the most effective distribution of exploration locations unless the site conditions are very uniform. The location of initial borings should be determined on the basis of condi- tions indicated by preliminary investigations. Loca- tions for subsequent or supplemental explorations should be chosen in a manner so as to result in the best definition of the foundation conditions on the basis of conclusions derived from earlier exploratory work.

Whereve feasible, the locations of subsurface ex- plorations should be chosen to permit the construc- tion of geological cross sections in important subsur- face views of the site.

It is essential to verify during construction that in situ conditions have been realistically estimated dur- ing analysis and design. Excavations made during construction provide opportunities for obtaining ad- ditional geologic and geotechnical data. All construc- tion excavations for safety-related structures and other excavations important to the verification of subsurface conditions should be geologically mapped and logged in detail. Particular attention should be given to the identification of thin strata or other geologic features that may be important to founda- tion behavior but. because of their limited extent, were previously undetected in the investigations program. If subsurface conditions substantially differ from those anticipated, casting doubt on the ade- quacy of the design or expected performance of the foundation. there may be a need for additional ex- ploration and redesign.

b. lnvestigations Related to SpeciflC Site Conditions Investigations for specific site conditions should in- clude the following:

(I) Rock. The engineering characteristics of rocks are related primarily to their structure. bed- ding. jointing, fracturing, weathering, and physical properties. Core samples are needed to observe and define these features. Suitable coring methods should be employed in sampling, and rocks should be sampled to a depth below which rock characteristics do not influence foundation performance. Deeper borings'mav be needed to investigate zones critical to the evaluation of the site geology. Within the depth intervals influencing foundation performance. zones of poor core recovery, low RQD (Rock Quality Designation).* dropping of rods. lost drilling fluid circulation. zones requiring casing. and other zones where drilling difficulties are encountered should be investigated by means of suitable logging or in situ observation methods to determine the nature.

geometry. and spacing of any discontinuities or anomolous zones. %%'here soil-filled voids, channels, or fissures are encountered. representative samples*

of the filling materials are needed. Where there is evidence of significant residual stresses, they should be evaluated on the basis of in situ stress or strain measurements.

(2) Granular Soils. Investigations of granular soils should include borings with splitspoon sampling and Standard Penetration Tests with sufficient coverage to define the soil profile and variations of soil conditions. Soundings with cone penetration tests may also be used to provide useful supplemental data if the device is properly calibrated to site condi- tions.

Suitable samples should be obtained for soil iden- tification and classification, in situ density determina- tions. mechanical analyses, and anticipated laboratory testing. In these investigations, it is impor- tant to obtain the best possible undistrbed samples*

for testing to determine whether the sands are suf- ficiently dense to preclude liquefaction or damaging cyclic deformation. The number and distribution of samples will depend on testing requirements and the variability of the soil conditions. In general, however, samples should be included from at least one prin- cipal boring* at the location of each Category I struc- ture. Samples should be obtained at regular intervals in depth and when changes in materials occur.

Criteria for the distribution of samples are given in regulatory position 5.

Granular soils containing coarse gravels and boulders are among the most difficult materials to

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sample. Obtaining good quality samples in these coarser soils often requires the use of trenches, pits.

or other accessible excavations* into the zones of in- terest. Also, extreme care is necessary in interpreting results from $he Standard Penetration Test in these materials. Often such data are misleading and may have to be disregarded. When sampling of these coarse soils is difficult. informationthat may be lost when the soil is later classified in the lhboratory should be recorded in the field. This information should include observed estimates of percent cobbles, boulders, and coarse material and their hardness.

shape, surface coating. and degree of weathering of coarse materials.

(3) Moderately v Compressible or Normally Con- solidated Clay' or Clay ve Soils. The properties of a fine grained soil are related to its in situ structure.*

and therefore the recovery and testing of good un- disturbed samples are necessary. Criteria for the dis- tribution and methods for obtaining undisturbed samples are discussed in regulatory position 5.

(4) Stibsurjaice Cavilies. Subsurface cavities may occur in water-soluble rocks. lavas, or weakly in- durated sedimentary rocks as the result of subterra- nean solutioning and erosion. Because of the wide distribution of carbonate rocks in the United States.

the occurrence of features such as cavities, sinkholes.

and solution-widened joint openings is common. For this reason, it is best to thoroughly investigate any site on carbonate rock for solution features to deter- mine their influence on the performance of founda- tions.

Investigations may be carried out with borings alone or in conjunction with accessible excavations, soundings, pumping tests, pressure tests, geophysical surveys, or a combination of such methods. The in- vestigation program will depend on the details of the site geology and the foundation design.

Indications of the presence of cavities, such as zones of lost drilling fluid circulation, water flo\\%ing into or out of drillholes, mud fillings, poor core recovery, dropping or settling of drilling rods.

anomalies in geophysical surveys, or in situ tests that suggest voids, should be followed up with more detailed investigations. These investigations should include excavation to expose solution features or ad- ditional borings that trace out such features.

The occurrence, distribution, and geometry of sub- surface cavities are highly unpredictable, and no preconstruction exploration program can ensure that all significant subsurface voids will be fully revealed.

Experience has shown that solution features may re- main undetected even where the area has been in- vestigated by a large number of borings. Therefore, where a site is on solution-susceptible rock, it may sometimes be necessary to inspect the rock after strip- ping or excavation is complete and the rock is ex- posed.

Remedial grouting or other corrective measures should be employed where necessary.

(5) Materials Lb.suitahhle Jbr Fotmdatitnhs. Bor- ings and representative sampling and testing should be completed to delineate the boundaries of un- suitable materials, These boundaries should be used to define the required excavation limits.

(6) Borrow Materials. Exploration of borrow sources requires the determination of the location and amount of borrow fill materials available.

Investigations in the borrow areas should be of suf- ficient hori.,;mal and vertical intervals small enough to determine the material variability and should in- clude adequate sampling of representative materials for laboratory testing.

c. Sam...nt All soil and rock samples obtained for testing should be representative. In many cases, to establish physical properties it is netcssary to obtain un- disturbed samples that preserve the in situ structure of the soil. The recovery of undisturbed samples is discussed in Section B.6 of this guide.

Sampling of soils should include. as a minimum.

recovery of samples for all principal borings at regular intervals and at changes in strata. A number of samples sufficient to permit laboratory determina- tion of average material properties and to indicate their variability is necessary. Alternating splitspoon and undi!;Iurbed samples with depth is recom- mended. Where sampling is not continuous, the elevations at which samples are taken should be stag- gered from boring to boring so as to provide con- tinuous coverage of samples within the soil column.

In supplementary borings,* sampling may be con- fined to the zone of specific interest.

Relatively thin zones of weak or unstable soils may be contained within more competent materials and may affect the engincering properties of the soil or rock. Continuous sampling in subsequent borings is needed through these suspect zones. Where it is not possible to obtain continuous samples in a single bor- ing. samples may be obtained from adjacent closely spaced borings in the immediate vicinity and may be used as representative of the material in the omitted depth intervals. Such a set of borings should be con- sidered equivalent to one principal boring.

d. Determining the Engineering Properties of Sub- surface Materials The shear strengths of foundation materials in all zones subjected to significant imposed stresses must

0

1.132-5

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I

be determined to establish whether they are adequate to support the imposed loads with an appropriate margin of safety. Similarly, it is necessary both to determine the compressibilities and swelling poten- tials of all materials in zones subjected to significant changes of compressive stresses and to establish that the deformations will be acceptable. In some cases these determinations may be made by suitable in situ tests and classification tests. Other situations may re- quire the laboratory testing of undisturbed samples.

Determination of dynamic modulus and damping values for soil strata is required 'or earthquake response analyses. These determinations may be made by laboratory testing of suitable undisturbed samples in conjunction with appropriate in situ tests.

5. Methods and Procedures for ExpLuratory Drilling In nearly ever%, site investigation, the primary means Of subsurface exploration are borings and borehole sampling. Drilling methods and procedures should be compatible with sampling requirements and the methods of sample recovery.

The top of the hole should be protected by a suitable surface casing where needed. Below ground surface, the borehole should be protected by drilling mud or casing. as necessary, to prevent caving and disturbance of materials to be sampled. The use of drilling mud is preferred to prevent disturbance when obtaining undisturbed samples of granular soils.

However, casing may be used if proper steps are taken to prevent disturbance of the soil being sampled and to prevent upward movement of soil into the casing, Washing with open-ended pipe for cleaning or advancing sample borcholes should not be permitted. Bottom-discharge bits should be used only with low-to-medium fluid pressure and with upward-deflected jets.

The groundwater or drilling mud level should be measured at the -start and end of each work day for borings in progress, at the completion of drilling, and at least 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after drilling is completed, In addi- tion to pertinent information normally recorded, all depths and amounts of water or drilling mud losses, together with depths at which circulation is recovered, should be recorded and reported on bor- ing logs and on geological cross sections. Logs and sections should also reflect incidents of settling or dropping of drill rods, abnormally low resistance to drilling or advance of samplers, core losses, in- stability or heave of the side and bottom of borcholes, influx of groundwater, and any other special feature or occurrence. Details of information that should be presented on logs of subsurface in- vestigations are given in regulatory position 2.

Depths should be measured to the nearest tenth of a foot and be correlatable to the elevation datum used for the site. Elevations of points in the borehole should also be determined with an accuracy of +/-0. I

ft. Deviation surveys should be run in all boreholes that are used for crosshole seismic tests and in all boreholes where deviations are significant to the use of data obtained. After use, it is advisable to grout each borehole with cement to prevent vertical move- ment of groundwater in the borehole.

6. Recovery of Undisturbed Soil Samples The best undisturbed samples are often obtained by carefully performed hand trimming of block sam- pies in accessible excavations. However, it is normal- ly not practical to obtain enough block samples at the requisite spacings and depths by this method alone. It is customary, where possible, to use thin-wall tube samplers in borings for the major part of the un- disturbed sampling. Criteria for obtaining un- disturbed tube samples are given in regulatory posi- tion 5.

The recovery of undisturbed samples of good quality is dependent on rigorous attention to details or equipment and procedures. Proper cleaning of the hole. by methods that do not produce avoidable dis- turbance of the soil, is necessary before sampling.

The sampler should be advanced in a manner that does not produce avoidable disturbance. For exam- ple, when using fixed-piston-type samplers. the drill- ing rig should be firmly anchored, or the piston should be fixed to an external anchor, to prevent its moving upward during the push of the sampling tube.

Care should be taken to ensure that the sample is not disturbed during its removal from the borehole or in disassembling the sampler. References 2 and 3 provide descriptions of suitable proccedures for ob- taining undisturbed samples.

With the conscientious use of proper field tech- niques, undisturbed samples in normally con- solidated clays and silts can usually be recovered by means of fixed-piston-type thin-wall tube samplers without serious difficulty. Recovery of good un- disturbed samples in sands requires greater care than in clays, but with proper care and attention to detail, they can also be obtained with fixed-piston-type thin- wall tube samplers in most sands that are free of bouiders and gravel size particles. Appendix B lists a number of sampling methods that are suitable for use in these and other materials.

Undisturbed samples of boulders, gravels, or sand- gravel mixtures generally are difficult to obtain, and often it is necessary to use hand sampling methods in test pits, shafts, or other accessible excavations to get good samples.

When obtaining undisturbed samples of granular soils below the groundwater table, dewatering by means of well points or other suitable methods may

1.132-6

he required. Osterberg and Varaksin (Ref. 4) describe a sampling program using dewatering of a shaft in sand with a frozen surrounding annulus. Samples suitable for density determination, though not for tests of mnichanical properties. may sometimes be ob- tained I'roi* boreholes with the help of chemical stabilization or impregnation (Refs. 5. 6). Special prcautions are required when toxic chemicals are used. Also. where aquifers are involved, it may not be advisable to injeit chemicals or grouts into them.

Useful discussions of methods of sampling granular soils are given by l-vorslev (Ref. 7) and Barton (Rer. 8).

7. Handling. Field Storage, and Transporting of Sam- ples Treatoiient of samples after their recovery from the ground is as critica0l to their quality as the procedures used in obtaining them. Samples of cohesionless soils are particularly sensitive to disturbance in handling and require extreme care during removal from the borehole, removal from the sampler. and subsequent handling in order to prevent disturbance from impact and vibration (Ref. 2). Special precautions are re- quired in transporting undisturbed samples because of their sensitivity to vibration and impact. They should be kept in a vertical position at all times.

should be well padded to isolate them from vibration and impacts. and should be transported with extreme care. Transportation by commercial carriers is not advisable.

Block samples should be handled by methods that give them equivalent protection from disturbance.

All undisturbed samples should be properly sealed and protected against moisture loss.

Disturbed samples* may be sealed in the same way as undisturbed samples. if in tubes. or may be placed in suitably marked, noncorroding. airtight con- tainers. Large representative samples may be placed in plastic bags, in tightly woven cloth, or in noncor- roding cans or other vessels that do not permit loss of fine particles by sifting. Such samples may be trans- ported by any convenient means.

Rock cores need to be stored and transported in durable boxes provided with suitable dividers to pre- vent shifting of the cores in any direction. They should be clearly labeled to identify the site, the bor- ing number, the core interval, and the top and hot- tom depths of the core. If the box has a removable lid, labeling should be placed on both the outside and inside of the box, as well as on the lid. Special con- tainers may be required to protect samples to be used for fluid content determinations and shale samples to be used for tests of mechanical properties from changes in fluid content. Core samples should be transported with the care necessary to avoid breakage or disturbance.

C. REGULATORY POSITION

rhe site investigations program needed to deter- mine foundation conditions at a nuclear po%ker plant site is highly dependent on actual site conditions. The program should he flexible and adjusted as the site in- vestigation proceeds with the advice of experienced personnel familiar with ti, site. The staff will revie\\%

the results of each site investigation program on a case-by-case basis and make an independent evaluv,- tion of foundation conditions in order to judge the adequacy of the information presented.

1. General Site Iniestigation Site investigations for nuclear power plants Si.ould be adequaite. in terms of thoroughness. suit:*bility of the methods used. quality of execution o ' the work.

and documentation. to permit an accurate determina- tion of the geologic and geotechnical conditions that affect the design. performance, and safe(ty of the plant. The investigations should provide information needed to assess foundation conditions at the site ::nd to perform engineering analysis and design with reasonable assurance that foundation conditions have been realistically estimated.

Information to be developed should, as ap- propriate. include (I) topographic. hydrologic.

hydrographic, and geologic maps: (2) plot plans.

showing locations of major structures and explora- tions: (3) boring logs and logs of trenches and excava- tions: and (4) geologic profiles showing excavation limits for structures and geophysical data such as time-distance plots. profiles, and inhole surveys.

Positions of all boreholes. piezometers. observation wells. soundings. trenches, exploration pits. and geophysical investigations should be surveyed in both plan and elevation and should be shown on plot plans. geologic sections, and maps. All surveys should be related to a fixed datum. The above infor- mation should be in sufficient detail and be in- tegrated to develop an overall view of the project and the geologic and geotechnical conditions affecting it.

2. Logs of Subsurface Imestigations Boring logs should contain the date when the bor- ing was made. the location of the boring with reference to the coordinate system used for the site.

the depths of borings, and the elevations with respect

to a permanent bench mark.

The logs should also include the elevations or the top and bottom of borings and the level at which the water table and the boundaries of soil or rock strata were encountered, the classification and description of the soil and rock layers, blow count values ob- tained from Standard Penetration Tests, percent recovery of rock core, and Rock Quality Designation

1.132-7

I-

(RQD). Results of field permeability *tests and borehole logging should also be included on logs. The type of tools used in making the boring should be recorded. It' the tools were changed, the depth at which the change was made and the reason for the change should be noted. Notes should be provided of everything significant to the interpretation of subsur- face conditions, such as lost drilling fluid, rod drops, and changes in drilling rate. Incomplete or aban- doned borings should be described with the same care as successfully completed borings. Logs of trenches and exploratory excavations should be presented in a format similar to the boring logs. The location of all explorations should be shown on the geologic section together with elevations and important data.

3. Procedures for Subsurface lnvestigations Some techniques widely used for subsurface in- vestigations are listed in Appendix B. It also cites ap- propriate standards and references procedures from published literaturelwith general guidelines on the ap- plicability, limitations, and potential pitfalls in their use. Additional suitable techniques are provided by other literature listed in Appendix D. The use or in- vestigations and sampling techniques other than those indicated in this guide is acceptable when it can be shown that the alternative methods yield satisfac- tory results. The attainment of satisfactory results in driiling, sampling, and testing is dependent on the techniques used, on care in details of operations, and on timely recognition of and correction of potential sources of error. Field operations should be super- vised by experienced professional personnel at the

.site of operations, and systematic standards of prac- tice should be followed. Procedures and equipment used to carry out the field operations should be documented, as should all conditions encountered in all phases of investigations. Experienced personnel thoroughly familiar with sampling and testing procedures should also inspect and document sampl- ing results and transfer samples from the field to storage or laboratory facilities.

4. Spacing and Depth of Subsurface Investigations Criteria for the spacing and depth of subsurface ex- ploration at locations or safety-related structures for favorable or uniform gcologic conditions are given in Appendix C. The application of these criteria is dis- cussed in Section B.4 of this guide, The investigative effort required for a nuclear power plant should be greatest at the locations of Category I structures and may vary in intensity and scope in other areas ac- cording to their spatial and geolgical relations to the site.

5. Sampling Sampling of soils should include, as a minimum, the recovery of samples at regular intervals and at changes in materials. Alternating splitspoon and un- disturbed samples with depth is recommended.

For granular soils, samples should be taken at depth intervals no greater than 5 feet. Beyond a depth of 50 feet below foundation level, the depth interval for sampling may be increased to 10 feet. Also it is recommended tital onw or more borings for each ma- jor structure be contiuously sampled. The borirg should be reamed and cleaned between samples. Re- quirements fe" undisturbed sampling of granular soils will depend on actual site conditions and re- quirements for laboratory testing. Some general guidelines for recovering undisturbed samples are given in Section B.4.b(2) and Section B.6 of the dis- cussion of this guide. Experimentation with different sampling techniques may be n,:cessary to determine the method best suited to local soil conditions.

For compressible or normally consolidated clays.

undisturbed samples should be continuous throughout the compressible strata in one or more principal borings for each major structure. These samples should be obtained by means of suitable fixed-piston-type thin-wall tube samplers or by methods that yield samples of equivalent quality.

Borings used for undisturbed sampling of soils should be at least 3 inches in diameter. Criteria for obtaining undisturbed tube samples include the fol- lowing:

a. Tubes should meet the specifications of ASTM Standard D 1587-67 (Ref. 9):

b. The Area Ratio* of the sampler should not exceed 13 percent and preferably should not exceed

10 percent:

c. The Specific Recovery Ratio* should be between 90 and 100 percent: tubes with less recovery may be acceptable if it appears that the sample may have just broken off and otherwise appears essential- ly undisturbed:

d. The Inside Clearance Ratio* should be the minimum required for complete sample recovery, e. Samples recovered should contain no visible distortion of strata or opening or softening or materials brought about by the sampling procedure.

6. Retention of Samples, Rock Core, and Records Samples and rock cores from principal borings should be retained at least until the power plant is licensed to operate and all matters relating to the in- terpretation of subsurface conditions at the site have been resolved. The need to retain samples and core beyond this time is a matter of judgment and should

6

1.132-8 II

b

0

he evaluated on a case-by-case basis. Soil samples in tubes will deteriorate with time and will not be suitable for any undisturbed testing. However, they may be used as a visual record of what the foundation material is like. Similarly, core or rock subject to slaking and rapid weathering such as shale will also deteriorate. It is recommended that photographs of scil samples and rock core togedher with field and final logs of all borings and record samples with material descriptions be preserved for a permanent record. Other important records of the subsurface in- vestigations program should also be preserved.

D. IMPLEMENTATION

This guide will be used by the staff to evaluate the results of site investigations, including the adequacy and quality of data provided to define foundation conditions and the geotechnical parameters needed for engineering analysis and design. submitted in con- nection with construction permit applications docketed after June 1. 1978. The staff will also use this guide to evaluate the results of any new site in- vestigations performed after June 1, 1978.

by a person whose construction permit was issued on or before June 1. 1978.

1.132-9

APPENDIX A

DEFINITIONS

For the convenience of the user, the following terms are presented with their definitions as used in this guide:

Accessible exca'ation-an excavation made for the purpose of investigating and sampling materials or conditions below the ground surface, of such shape and dimensions as to permit the entry of personnel for direct examination, testing, or sampling.

Area Ratio- (Ca) of a sampling device is defined as:

D: -13 a

De where Do is the outside diameter of that part of the sampling device that is forced into the soil, and De is the inside diameter, normally the diameter of the cut- ting edge.

Boring-ian exploratory hole in soil or rock, or both, made by removal of materials in the form of samples or cuttings (cf. soundings).

Disturbed sample-a sarpple whose internal struc- ture has been altered to such a degree that it does not reasonably approximate that of the material in situ.

Such a sample may be completely remolded, or it may bear a resemblance to an undisturbed sample in having preserved the gross shape given it by a sampl- ing device.

Geoteclmical-of or pertaining to the earth sciences (geology, soils, seismology, and groundwater hydrology) and that part of civil engineering which deals with the interrelationship between the geologic environment and the works of man.

In situ test-a test performed on in-place soil or rock for the purpose of determining some physical property. As used in this guide, it includes geophysical measurements.

Inside Clearance Ratio (Ci) of a sampling device is defined as:

Di - De i

De where Di is the inside diameter of the sample tube or liner and D. is the diameter .of the cutting edge.

Observation well-an open boring that permits measuring the level or elevation of the groundwater table.

Piezoineter-a device or instrument for measuring pore pressure or hydraulic potential at a level or point below the ground surface.

Principal borings-those exploratory holes that are used as the primary source of subsurface informa- tion. They are used to explore and sample all soil or rock strata wi~hin the interval penetrated to define the geology of the site and to determine the properties of the subsurface materials. Not included are borings from which no samples are taken, borings used to in- vestigate specific or limited intervals, or borings so close to others that the information yielded repre- sents essentially a single location.

Representative sample-a sample that (1) contains approximately the same mineral constituents of the stratum from which it is taken, in the same propor- tions, and with the same grain-size distribution and

(2) is uncontaminated by foreign materials or chemical alteration.

Rock Quality Designation (RQD)-an indirect measurement of the degree of rock fracturing and jointing and rock quality. It is calculated by summing the lengths of all hard and sound pieces of recovered core longer than 4 inches (10cm) and dividing the sum by the total length of core run.

Sounding-an exploratory penetration below the ground surface by means of a device that is used to measure or observe some in situ property of the materials penetrated. usually without recovery of samples or cuttings.

Specific Recovery Ratio-(R.) in the advance of a sample tube is defined as:

Rs=

where AL is the increment of length of sample in the tube corresponding to an increment AH of sampler advance.

Soil structure-a complex physical-mechanical property, defined by the sizes, shapes, and arrange- ments of the constituent grains and intergranular matter and the bonding and capillary forces acting among the constituents.

Supplementary borings or supplementary soundings-borings or soundings that are made in ad- dition to principal borings for some specific or limited purpose.

Undisturbed sample-a sample obtained and treated in such a way that disturbance of its.original structure is minimal, making it suitable for laboratory testing of material properties that depend on structure.

1.132-10

APPENDIX B

METHODS OF SUBSURFACE EXPLORATION'

METHOD

PROCEDURE

A PPLI CA BI LITY

LIMITATIONS

METHODS OF ACCESS FOR SAMPLING, TEST. OR OBSERVATION

7-=

Pits, Trenches, Shafts, Tunnels Auger Boring Hollow Stem Auger Boring Wash Boring Rotary Drilling Excavation made by hand, large auger, or digging machinery. (Ref. 7)

Boring advanced by hand auger or power auger.

(Ref. 7)

Boring advanced by means of continuous-flight helix auger with hollow center stem. (Ref. 10)

Boring advanced by chopping with light bit and by jetting with upward-deflected jet. (Ref. 7)

Boring advanced by ro- tating drilling bit;

cuttings removed by circulating drilling fluid. (Ref. 7)

Visual observation, photo- graphy, disturbed and un- disturbed sampling, in sitt.

testing of soil and rock.

Recovery of remolded samples, and determining groundwater levels. Access for undisturbed sampling of cohesive soils.

Access for undisturbed or representative sampling through hollow stem with thin-wall tube sampler, core barrel, or split- barrel sampler.

Cleaning out and advancing hole in soil between sample intervals.

Cleaning out and advanc- ing hole in soil or rock between sample intervals.

Depth of unprotected excava- tions is limited by ground- water or safety considerations.

Will not penetrate boulders or most rock.

Should not be used with plug in granular soils. Not suitable for undisturbed sampling in loose sand or silt. (Ref. I1)

Suitable for use with sampling operations in soil only if done with low water velocities and with upward-deflected jet.

Drilling mud should be used in granular soils. Bottom discharge bits are not suitable for use with undisturbed sampling in soils un- less combined with protruding core barrel, as in Denison -.ampler, or with upward-deflected jets.

Scc also Rers. 32-40.

APPENDIX B (Continued)

METHODS OF SUBSURFACE EXPLORATION

METHOD

PROCEDURE

APPLICABILITY

LIMITATIONS

METHODS OF ACCESS FOR SAMPLING, TEST, OR OBSERVATION

Percussion Drilling Boring advanced by air-operated impact hammer.

I~

Cable Drilling Continuous Sampling or Displacement Boring Boring advanced by repeated dropping of heavy bit: removal of cuttings by bailing.

(Ref. 7)

Boring advanced by repeated pushing of sampler or closed sampler is pushed to desired depth, and sample is taken. (Ref. 7)

Detection of voids and zones of weakness in rock by changes in drill rate or resistance. Access for in situ testing or logging.

Advancing hole in soil or rock. Access for sampling, in situ testing, or logging in rock. Pene- tration of hard layers, gravel, or boulders in auger borings.

Recovery of representative samples of cohesive soils and undisturbed samples in some cohesive soils.

Causes severe disturbance in soils- not suitable for use with undis- turbed sampling methods.

Effects of advance and withdrawal of sampler result in disturbed sections at top and bottom of sample. In some soils, entire sample may be disturbed. Best suited for use in cohesive soils. Continuous sampling in cohesionless soils may be made by successive reaming and cleaning of hole between sampling.

Not suitable for use in soils.

METHODS OF SAMPLING SOIL AND ROCK'

Hand-Cut Block or Cylindrical Sample

l. AND ROCK

Dutch Cone Penetrometer co Field Vane Shear Test Steel cone is pushed into soil and followed by subsequent advance of friction sleeve.

Resistance is measured during both phases of advance. (Ref. 20),

Four-bladed vane is pushed into undisturbed soil. then rotated to cause shear failure on cylindrical surface.

Torsional resistance versus angular deflec- tion is recorded. (Ref. 9)

Expendable steel cone is driven into soil by blows of falling weight. Blow count versus penetration is recorded. (Ref. 13)

Steel loading plate is placed on horizontal surface and is stati- cally loaded, usually by hydraulic jack. Settle- ment versus time is recorded for each load increment. (Ref. 9)

Detection of changes in consistency or relative density in clays or sands.

Used to estimate static undrained shear strength of clay. Used with empiri- cal relationships to obtain estimate of static compres- sibility of sand.

Used to estimate in situ undrained shear strength and sensitivity of clays.

Strength estimates require onsite verification by other methods of testing.

Not suitable for use in silt, sand.

or soils containing appreciable amounts of gravel or shells. May yield unconservative estimates of shear strength in fissured clay soils or where strength is strain- rate dependent.

Provides no quantitative infor- mation on soil properties.

Results can be extrapolated to loaded areas larger than bearing plate only if properties of soil are uniform laterally and with depth.

0

Drive-Point Penetrometer Plate Bearing Test (Soil)

Detection of gross changes in consistency or relative density. May be used in some coarse granular soils.

Estimation of strength and moduli of soil. May be used at ground surface, in excava- tions, or in boreholes.

0

rn~_

APPE

'B (Continued)

METHODS OF SUBSURFACE EXPLORATION

METHOD

PROCEDURE

APPLICABILITY

LIMITATIONS

METHODS OF IN SITU TESTING OF SOIL AND ROCK

Plate Bearing Test or Plate Jacking Test (Rock)

Pressure Meter Test (Dilatometer Test)

7- Field Pumping Test Direct Shear Test Bearing pad on rock surface is statically loaded by hydraulic jack. Deflection versus load is recorded.

(Ref. 21)

Uniform radial pressure is applied hydraulically over a length of borehole several times its diame- ter. Change in diameter versus pressure is recorded.

(Ref. 21)

Water is pumped from or into aquifer at constant rate through penetrating well. Change in piezo- metric level is measured at well and at one or more observation wells. Pumping pressures and flow rates are recorded. (Refs. 22. 23)

Block of in situ rock is isolated to permit shearing along a preselected sur- face. Normal and shearing loads are applied by jacking.

Loads and displacements are recorded. (Ref. 24)

Estimation of elastic moduli of rock masses. May be used at ground surface, in exca- vations, in tunnels, or in borcholes.

Estimation of elastic moduli of rocks and estimation of shear strengths and compress- ibility of soils by empirical relationships.

Estimation of in situ permea- bility of soils and rock mass.

Measurement of shearing resistance of rock mass in situ.

Results can be extrapolated to loaded areas larger than bearing pad only if rock properties are uniform over volume of interest and if diameter of bearing pad is larger than average spacing of joints or other discontinuities.

Test results represent properties only of materials in near vicinity of borehole. Results may be mis- leading in testing materials whose properties may be anisotropic.

Apparent permeability may be greatly influenced by local features. Effective permeability of rock is dependent primarily on frequency and distribution ofjoints. Test result in rock is representative only to extent that segment penetrated by borehole.

is representative of joint system of rock mass.

Tests are costly. Usually variability of rock mass requires a sufficient number of tests to provide statistical control.

APPENDIX B (Continued)

METHODS OF SUBSURFACE EXPLORATION

METHOD

PROCEDURE

A PPIC A BI LITY

L.IMITATIONS

METHODS OF IN SITU TESTING OF SOIL AND ROCK

0

Pressure Tunnel Test Radial Jacking Test Borehole Jack Test Borehole Deformation Meter Hydraulic pressure is applied to sealed-off length of circular tunnel, and diametral deformations are measured.

(Ref. 21)

Radial pressure is applied to a length of circular tunnel by flat jacks. Dia- metral deformations are measured.

Load is applied to wall of borehole by two diametric- ally opposed jacks. Deform- ations and pressures are recorded. (Ref. 25)

Device for measurement of diameters (deformation meter) is placed in bore- hole, and hole is overcored to relieve stresses on annular rock core contain- ing deformation meter.

Diameters (usually 3) are measured before and after overcoring. Modulus of rock is measured by laboratory tests on core; stresses are computed by elastic theory. (Ref, 26)

Determination of elastic constants of the rock mass in situ.

Same as pressure tunnel test.

Determination of elastic modulus of rock in situ.

Capable of applying greater pressures than dilatome- ters.

Measurement of absolute stresses in situ.

Volume of rock tested is dependent on tunnel diameter. Cracking due to tensile hoop stresses may affect apparent stiffness of rock.

Same as pressure tunnel test.

Apparent stiffness may be affected by development of tension cracks.

Stress field is affected by borehole. Analysis subject to limitations of elastic theory.

Two boreholes at different orien- tations are required for determi- nation of complete stress field.

Questionable results in rocks with strongly time-dependent properties.

APPENDIX B (Continued)

METHODS OF SUBSURFACE EXPLORATION

METHOD

PROCEDURE

APPLICABILITY

LIMITATIONS

METHODS OF IN SITU TESTING OF SOIL AND ROCK

Inclusion Stressmeter Borehole Strain Gauge IL-)

Rigid stress indicating device (stressmeter) is placed in borehole, and hole is overcored to relieve stresses on annu- lar core containing stress- meter. In situ stresses are computed by elastic theory. (Ref. 26)

Strain gauge is cemented to bottom (end) of bore- hole. and gauge is over- cored to relieve stresses on core containing strain gauge. Stresses are computed from resulting strains and from modulus obtained by laboratory tests on core.

(Ref. 26)

Slot is drilled in rock surface producing stress relief in adjacent rock.

Flat jack is grouted into slot and hydraulically pressurized. Pressure required to reverse deformations produced by stress relief is observed.

(Refs. 26. 27)

Measurement of absolute stresses in situ. Requires only one core drill size.

Measurement of one corn po- nent of normal stress in situ. Does not require knowledge of rock modulus.

Same as above.

Stress field is affected by excavation or tunnel. Interpre- tation of test results subject to assumption that loading and unloading moduli are equal.

Questionable results in rock with strongly time-dependent pruperties.

Measurement of absolute stresses in situ. Does not require accurate knowl- edge of rock modulus.

Same as above.

Flat Jack Test

APPENDIX B (Continued)

METHODS OF SUBSURFACE EXPLORATION

METHOD

PROCEDURE

APPLICABILITY

LIMITATIONS

METHODS OF IN SITU TESTING OF SOIL AND ROCK

Hydraulic Fracturing Test Crosshole Seismic Test Uphole/Downhole SeismicTest Acoustic Velocity Log Fluid is pumped into scaled- off portion of borehole with pressure increasing until fracture occurs.

(Ref. 26)

Seismic signal is trans- mitted from source in one borehole to receiv- er(s) in other bore- hole(s), and transit time is recorded. (Ref. 28)

Seismic signal is transmitted between borehole and ground surface, and transit time is recorded. (Ref. 28)

Logging tool contains transmitting transducer and two receiving trans- ducers separated by fixed gage length. Signal is transmitted through rock adjacent to borehole and transit time over the gage length is recorded as difference in arrival times at the receivers.

(Refs. 29. 30)

In situ measurement of com- pression wave velocity and shear wave velocity in soils and rocks.

Measurement of compression wave velocity. Used primar- ily in rocks to Obtain estimate of porosity.

Requires deviation survey of boreholes to eliminate errors due to deviation of holes from vertical. Refraction of signal through adjacent high-velocity beds must be considered in interpretation.

Apparent velocity obtained is time-average for all strata between source and receiver.

Results represent only the material immediately adjacent to the borehole. Can be obtained only in uncased, fluid-filled borehole. Use is limited to materials with P-wave velority greater than that of borehole fluid.

Estimation of minor principal stress.

Affected by anisotropy of tensile strength of rock.

0

APPENDIX B (Continued)

METHODS OF SUBSURFACE EXPLORATION

METHOD

PROCEDURE

A PPIJCABSILITY

ILIMITATIONS

METHODS OF IN SITU TESTING OF SOIL AND ROCK

3-D Velocity Log Electrical Resistivity Log Logging tool contains transmitting transducer and receiving transducer separated by fixed gage length. Signal is trans- mitted through rock adjacent to borehole. and wave train at receiver is recorded. (Ref. 31)

Apparent electrical resis- tivity of soil or rock in neighborhood of borehole is measured by in-hole logging tool containing one of a wide variety of electrode configurations.

(Refs. 29. 30)

Measurement of compression wave and shear wave velocity ties in rock. Detection of void spaces. open fractures, and zones of weakness.

Appropriate combinations of resistivity logs can be used to estimate porosity and degree of water saturation in rocks.

In soils, may be used as qualitative indication of changes in void ratio or water content, for correla- tion ofstrata between boreholes, and for location of strata boundaries.

Correlation of strata between boreholes and location of strata boundaries. Provides an approximation to water content and can be run in cased or uncased, fluid- filled or empty boreholes, Results represent only the material immediately adjacent to the borehole. Can be obtained only in uncased, Iluid-filled borehole. Correction required for variation in hole size. Use is limited to materials with P-

wave velocity greater than that of borehole fluid.

Can be obtained only in uncased borcholes. Hole must be fluid filled, or electrodes must be pressed against wall of hole.

Apparent resistivity values are strongly affected by changes in hole diameter, strata thickness, resistivity contrast between adja- cent strata. resistivity of drilling fluid, etc.

Because of very strong borehole effects, results are generally not of sufficient accuracy for quantitative engineering uses.

t-J

Neutron Log Neutrons are emitted into rock or soil around bore- hole by a neutron source in the logging tool, and a detector isolated from the source responds to either slow neutrons or secondary gamma rays.

Response of detector is recorded. (Refs. 29. 30)

APPENDIX B (Continued)

METHODS OF SUBSURFACE EXPLORATION

METHOD

PROCEDURE

APPLICA BILITY

IEMITATIONS

METHODS OF IN SITU TESTING OF SOIL AND ROCK

Gamma-Gamma Log

("Density Log")

Gamma rays are emitted into rock around the borehole by a source in the logging tool, and a detector isolated from the source responds to back-scattered gamma rays. Response of de- tector is recorded.

(Ref. 29)

Film-type or television camera in a suitable protective container is used for observation of walls of borehole.

(Ref. 32)

Estimation of bulk density in rocks, qualitative indi- cation of changes in densi- ty of soils. May be run in empty or fluid-Filled holes.

Detection and mapping of joints, seams, cavities, or other visually observable features in rock. Can be used in empty, uncased holes or in holes filled with clear water.

Effects of borehole size and density of drilling fluid must be accounted for. Presently not suitable for qualitative estimate of density in soils other than those of -rock-like"

character. Cannot be used in cased boreholes, Results are affected by any condition that affects visi- bility.

4'"

Borehole Cameras

APPENDIX C

SPACING AND DEPTH OF SUBSURFACE EXPLORATIONS FOR SAFETY-RELATED' FOUNDATIONS

TYPE OF STRUCTURE

General SPACING OF BORINGS' OR SOUNDINGS

For favorable, uniform geologic conditions, where continuity of subsurface strata is found. spacing should be as indicated for the type of structure with at least one boring at the location of every safety-related or Seismic Category I structure. Where variable conditions are found, spacing should be smaller, as needed, to obtain a clear picture of soil or rock properties and their variability. Where cavities or other discontinuities of engineering significance may occur, the normal exploratory work should be supplemented by borings or soundings at a spacing small enough to detect such features.

tb.j MINIMUM DEPTH OF PENETRATION

The depth of borings should be determined on the basis of the type of structure and geologic conditions. All borings should be extended to a depth sufficient to define the site geology and to sample all materials that may swell during excavation, may consolidate subsequent to construction, may be unstable under earthquake loading, or whose physical properties would affect foundation behavior or stability. Where soils are very thick, the maximum required depth for engineering purposes, denoted dmax, may be taken as the depth at which the change in the vertical stress during or after construction for the combined foundation loading is less than 10% of the in situ effective overburden stress. It may also be taken as the depth at which the shear wave velocity of the soil mass exceeds 3.000 ft/sec. It may be necessary to include in the investigation program several borings needed to complete information to establish the soil model for soil-structure interaction studies. These borings may be required to penetrate depths greater than those depths required for general ený;inecring purposes. Borings should be deep enough to define and evaluate the potential for deep soil stability problems at the site. Generally all borings should extend at least 30

feet below the lowest part of the foundation. If competent rock is encountered at lesser depths than those given, borings should penetrate to the greatest depth where discontinuities or zones of weakness can affect foundations and should penetrate at least 20 ft into sound rock. For weathered shale or soft rock.

depths should be as for soils.

'As dctcrmincd by I tt'jt1 lii ocaiiivns of .,ife .-relted structure.- and facififics.

'Includc. shafts or other accessible excvations that meet depth requirements.

APPENDIX C

SPACING AND DEPTH OF SUBSURFACE EXPLORATIONS FOR SAFETY-RELATED 3 FOUNDATIONS

TYPE OF STRUCTURE

Structures including buildings, retaining walls.

concrete dams.

Earth dams, dikes, levees, and embankments.

Deep cuts,6 canals SPACING OF BORINGS4 OR SOUNDINGS

Principal borings: at least one boring beneath every safety-related structure. For larger, heavier structures, such as the containment and auxiliary buildings, at least one boring per 10,000 sq ft (approximately 100 ft spacing) and, in addition, a number of borings along the periphery, at corners, and other selected locations. One boring per 100 linear ft for essentially linear structures.?

Principal borings: one per 100 linear ft along axis of structure and at critical locations perpendicular to the axis to establish geological sections and groundwater conditions for analysis.'

Principal borings: one per 200 linear ft along the alignment and at critical locations perpendicular to the alignment to establish geologic sections for analysis.!

MINIMUM DEPTH OF PENETRATION

Principal borings: at least one-fourth of the principal borings anid a minimum of one boring per structure to penetrate into sound rock or to a depth equal to dmax.

Others to a de;th below foundation elevation equal to the width of structure or to a depth equal to the foundation depth below the original ground surface.

whichever is greater.'

Principal borings: one per 200 linear ft to dmax. Others should penetrate all strata whose strength would affect stability. For water-impounding structures, to sufficient depth to define all aquifers and zones of underseepage that could affect performance of structure.-

Principal borings: one per 200 linear ft to penetrate into sound rock or to dmax. Others to a depth below the bottom elevation of"cavation equal to the depth of cut or to below, the lowest potential failure zone of the slope.! Borings should penetrate pervious strata below which groundwater may influence stability.

0%

AIso supplementary borings or soundings which are design dependent or nccessary to define anomalies. critical abutment conditions. etc.

Includes temporary cuts, open during construction. where loss of strength due to excessive deformations would affect ultimate site safety.

0

_____

-

--

____

APPENDIX C

SPACING AND DEPTH OF SUBSURFACE EXPLORATIONS FOR SAFETY-RELATED3 FOUNDATIONS

TYPE OF STRUCTURE

Pipelines Tunnels SPACING OF BORIN(;S4 OR SOUNDINGS

Principal borings: This may vary depending on how well site conditions are understood from other plant site borings. For variable conditions, one per 100 linear ft for buried pipelines: at least one boring for each footing for pipelines above ground.'

Principal borings: one per 100 linear ft.'

MINiNMUM DEPTH OF PENETRATION

Principal borings: For buried pipelines, one per 200

linear ft to penetrate into sound rock or to dmax. Others to 5 times the pipe diameters below the invert elevation.

For pipelines above ground. depths as for foundation structures.

Principal borings: one per 200 linear ft to penetrate into sound rock or to diiax. Others to 5 times the tunnel diameter below the invert elevation,'

1.-j

-j Reservoirs, impoundments Principal borings: one per 50,000 ft' of interior area of the impoundment. in addition to borings at the locations of dams or dikes.'

Principal borings: at least one-fourth. but no fewer than one, of the principal borings to penetrate into sound rock or to dmax. Others to a depth of 25 ft below rc.esrvoir bottom elevation.'

, Stippkllcn~iery horing, o~r %on ing ai nce'%JrY to define zin-naliics.

APPENDIX D

REFERENCES

1. U.S. Army Corps of Engineers, Instrumentation of Earth and Rock-Fill Dams (Groundwater and Pore Pressure Observations), Engineer Manual EM 1 110-2-

1908. 1972.

2. U.S. Army Corps of Engineers, Soil Sampling.

Engineer Manual EM 1110-2-1907. 1972, Ch. 3, 4.

3. U.S. Navy, Design Manual, Soil Mechanics, Founidations, andl Earth Structures. A',-1 VF,,l C DM-7.

Dept. of the Navy, Naval Facilities Engineering Command. Alexandria. Virginia, 1971.

4. Osterberg, J.O., and S. Varaksin, "Determina- tion of Relative Density of Sand Below Groundwater Table.~ Evaluation of Relative Densit' and Its Role in Geotechnical Projects inrowiving Cohesiohless Soils.

American Society for Testing and Materials.

Philadelphia. STP 523. 1973, pp. 364-376.

5. Karol. R. H.. "Use of Chemical Grouts to Sam- pie Sands,~ Sampling of Soil adl Rock, American Society for Testing and Materials, Philadelphia, STP

483, 19*71. pp. 51-59.

6. Windisch. S. J.. and M. Soulie. "Technique for Study of Granular Materials." J. Soil Mlech. Found.

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Philadelphia. 1974, pp. 192,194. 206-207, 224-229.

261.263, 317-320.

uo*rings,'

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346-379.

13. Terziaghi. K.. and R. B. Peck. Soil Alechlnics in Engineering Practice. 2nd ed., John Wiley and Sons, Inc., New York. 1963. pp. 299-300.308-314.

322-324.

14. Osterberg. J. 0., "New Piston Type Soil Sampler.'* Engineering Newiv-Record 148. 1952, pp.

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"111

8i4t1 "

(m

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132-28

(

1

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pp. 56-61.

1.132-29

APPENDIX E

BIBLIOGRAPHY

Bates. E. R.. "I)Deection of Subsurface Cavities."

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(;hIssop. R.. "-The Rise of Geotechnology and Its Inillnence on I-neineering Practice.'" Ieihtlh Rankine Leclure: Gvcechnique 1iI,2), 1968. pp. 105-150.

Hlall. W. J.. N. M. Newmark. and A. J. Hendron.

.Jr.. "Classification. Elngineering Properties and Field Exploratioll of Soils, Intact Rock. and In Situ Mas- s.es.'" US. AEC Report WASH-130). 1974.

iMisterek. 1). L., "'Analysis of Dlata from Radial Jack in Tests.-" /)eet'rmiaiiog tlf the In Sint .Mthldult of I)Ml10rmnlclion of Rock.

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Osterberg, .1. 0.. "An Improved Ilydraulic Piston Sampler." Proceedings olf the Eihth

/Inerlariona al COnh'rrence on Soil Aflechanics aniid Fotundatlion h'ngin'erinr, Mloscow. LUSSR, Vol. 1.2. 1973. pp. 317-

321.

Sh1a.nllnon.

Wilson. Inc., and Agbahian-.lacobsen Associates, "'Soil Behavior Under IEarthquake l.oading Conrditions: State-of-tle-A rt -valuatil tof"

Soil Characteristics fur Seismic Response An:iy.sis.'

U.S. .\\I:C Report. 1972.

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..

1oil Alech.

Fo"und. lv.. A\\merican Society of Civil I-ngincers.

1972. V. 98(SM5): pp. 481-490. V.98(SN16: pp. 557-

578. V. 98(SNI!7): pp. 749-764. V. 9,(SNIX): pp. 771-

785.

Wallace. G. 11.. I. .1. Slehir. and 1. :A. Anderson.

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1968. pp. 633-660.

0

1.132-30

Regulatory Guide 1.132

Contents

A. INTRODUCTION

h. ital

7. T PI

i. ni hs tit

C. REGULATORY POSITION

D. IMPLEMENTATION

l. AND ROCK

Navigation menu

Regulatory Guide 1.132

A. INTRODUCTION

h. ital

7. T PI

i. ni hs tit

C. REGULATORY POSITION

D. IMPLEMENTATION

l. AND ROCK

Navigation menu

Search