Regulatory Guide 1.132
| ML032790499 | |
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| Issue date: | 10/31/2003 |
| From: | Office of Nuclear Regulatory Research |
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| RG-1.132, Rev 2 | |
| Download: ML032790499 (15) | |
1As determined by the final locations of safety-related structures and facilities.
2Includes shafts or other accessible excavations that meet depth requirements.APPENDIX DSPACING AND DEPTH OF SUBSURFACE EXPLORATIONS FOR SAFETY-RELATED
1 FOUNDATIONS
STRUCTURESPACING OF BORINGS
2 OR SOUNDINGSMINIMUM DEPTH OF PENETRATIONGeneralFor favorable, uniform geologic conditions, whereThe depth of borings should be determined on the basis of the type continuity of subsurface strata is found, theof structure and geologic conditions. All borings should be extended recommended spacing is as indicated for the typeto a depth sufficient to define the site geology and to sample all of structure. At least one boring should be at thematerials that may swell during excavation, may consolidate subse- location of every safety-related structure. Wherequent to construction, may be unstable under earthquake loading, or variable conditions are found, spacing should bewhose physical properties would affect foundation behavior or smaller, as needed, to obtain a clear picture of stability. Where soils are very thick, the maximum required depth soil or rock properties and their variability. Wherefor engineering purposes, denoted dmax, may be taken as the depth atcavities or other discontinuities of engineeringwhich the change in the vertical stress during or after construction significance may occur, the normal exploratoryfor the combined foundation loading is less than 10% of the work should be supplemented by borings or effective in situ overburden stress. It may be necessary to include soundings at a spacing small enough to detect in the investigation program several borings to establish the soil such features.model for soil-structure interaction studies. These borings may berequired to penetrate depths greater than those required for general engineering purposes. Borings should be deep enough to define and evaluate the potential for deep stability problems at the site.
Generally, all borings should extend at least 10 m (33 ft) 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 or alteration can affect foundations and should penetrate at least 6 m
(20 ft) into sound rock. For weathered shale or soft rock, depths should be as for soils.
3Also supplementary borings or soundings that are design-dependent or necessary to define anomalies, critical conditions, etc.
4Includes temporary cuts that would affect ultimate site safety.Appendix D, ContinuedSTRUCTURESPACING OF BORINGS OR SOUNDINGSMINIMUM DEPTH OF PENETRATIONBuildings, Principal borings: at least one boring beneath At least one-fourth of the principal borings and a minimum of retaining every safety-related structure. For larger, one boring per structure to penetrate into sound rock or to a walls, heavier structures, such as the containment depth equal to dmax. Others to a depth below foundation concreteand auxiliary buildings, at least one boring perelevation equal to the width of structure or to a depth equal to dams900 m 2 (10,000 ft
2) (approximately 30 m the width of the structure or to a depth equal to the foundation (100 ft) spacing). In addition, a number of depth below the original ground surface, whichever is greater.
3borings along the periphery, at corners, and other selected location
s. One boring per
30 m (100 ft) for essentially linear structures.Earth dams,Principal borings: one per 30 m (100 ft) alongPrincipal borings: one per 60 m (200 ft) to dmax. Othersdikes,axis of structure and at critical locationsshould penetrate all strata whose properties would affect the levees,perpendicular to the axis to establish geologicalperformance of the foundation. For water-impounding embank-sections with groundwater conditions for structures, to sufficient depth to define all aquifers and zones mentsanalysis.
2of underseepage that could affect the performance of
structures.
2Deep cuts, 4Principal borings: one per 60 m (200 ft) alongPrincipal borings: One per 60 m (200 ft) to penetrate intocanalsthe alignment and at critical locations sound rock or to dmax. Others to a depth below the bottom perpendicular to the alignment to establishelevation of excavation equal to the depth of cut or to below geologic sections with groundwater conditionsthe lowest potential failure zone of the slope.
2 Borings shouldfor analysis.
2penetrate pervious strata below which groundwater may influence stability.
2 Appendix D, Continued STRUCTURESPACING OF BORINGS OR SOUNDINGSMINIMUM DEPTH OF PENETRATIONPipelinesPrincipal borings: This may vary dependingPrincipal borings: For buried pipelines, one of every three toon how well site conditions are understood penetrate sound rock or to dmax. Others to 5 times the pipe from other plant site borings. For variablediameters below the elevation. For pipelines above ground, conditions, one per 30 m (100 ft) for burieddepths as for foundation structures.
2pipelines; at least one boring for each footing for pipelines above ground.TunnelsPrincipal borings: one per 30 m (100 ft), 2 mayPrincipal borings: one per 60 m (200 ft) to penetrate into vary for rock tunnels, depending on rock typesound rock or to dmax. Others to 5 times the tunnel diameterand characteristics and planned exploratory below the invert elevation.
2,3shafts or adits.Reservoirs,Principal borings: In addition to borings at thePrincipal borings: At least one-fourth to penetrate that portionimpound-locations of dams or dikes, a number of of the saturation zone that may influence seepage conditions mentsborings should be used to investigate geologicor stability. Others to a depth of 7.5 m (25 ft) below reservoir conditions of the reservoir basin. The numberbottom elevation.
2and spacing of borings should vary, with the largest concentration near control structures and the coverage decreasing with distance upstream.Sounding = An exploratory penetration below the ground surface used to measure or observe an in situ property of subsurface materials,usually without recovery of samples or cuttings.Principal boring = A borehole used as a primary source of subsurface information. It is used to explore and sample all soil orrock strata penetrated to define the site geology and the properties of subsurface materials. Not included are borings from which no samples are taken, borings used to investigate specific or limited intervals, or borings so close to others that information obtained represents essentially a single location.
APPENDIX EApplications of Selected Geophysical Methods for Determination of Engineering ParametersGeophysical MethodBasic MeasurementApplicationAdvantagesLimitationsSurfaceRefraction (seismic)Travel time ofcompressional waves through subsurface layersVelocity determination ofcompression wave through subsurface. Depths to contrasting interfaces and geologic correlation of horizontal layersRapid, accurate, and relativelyeconomical technique.
Interpretation theory generally straightforward and equipment readily availableIn saturated soils, the compression wave velocityreflects mostly wave velocities in the water, and thus is not indicative of soil properties.Reflection (seismic)Travel time ofcompressional waves reflected from subsurface layersMapping of selected reflectorhorizons. Depth determinations, fault detection, discontinuities, and other anomalous featuresRapid, thorough coverage of givensite area. Data displays highly effective.
In saturated soils, the compression wave velocityreflects mostly wave velocities in the water, and thus is not indicative of soil properties.Rayleigh wavedispersionTravel time andperiod of surface Rayleigh wavesInference of shear wavevelocity in near-surface materialsRapid technique which usesconventional refraction seismographsCoupling of energy to the ground may be inefficient,restricting extent of survey coverage. Data resolution and penetration capability are frequency-dependent;
sediment layer thickness and/or depth interpretations must be considered approximate.Vibratory (seismic)Travel time orwavelength of surface Rayleigh wavesInference of shear wavevelocity in near-surface materialsControlled vibratory source allowsselection of frequency, hence wavelength and depth of penetration [up to 60 m (200 ft)].
Detects low-velocity zones underlying strata of higher velocity.
Accepted method Coupling of energy to the ground may be inefficient,restricting extent of survey coverage. Data resolution and penetration capability are frequency-dependent;
sediment layer thickness and/or depth interpretationsmust be considered approximate
.Reflection profiling(seismic-acoustic)Travel times ofcompressional waves through water and subsurface materials and amplitude of reflected signal.Mapping of various lithologichorizons; detection of faults, buried stream channels, and salt domes, location of buried man-made objects; and depth determination of bedrock or other reflecting horizons.Surveys of large areas at minimaltime and cost; continuity of recorded data allows direct correlation of lithologic and geologic changes; correlative drilling and coring can be kept to a minimum.Data resolution and penetration capability isfrequency- dependent; sediment layer thickness and/or depth to reflection horizons must be considered approximate unless true velocities are known; some bottom conditions (e.g., organic sediments) prevent penetration; water depth should be at least 5 to 6 m
(15 to 20 ft) for proper system operation.Electrical resistivityElectrical resistanceof a volume of material between
probesComplementary to refraction(seismic). Quarry rock, groundwater, sand and gravel prospecting. River bottom studies and cavity detection.Economical nondestructivetechnique. Can detect large bodies of "soft" materials.Lateral changes in calculated resistance ofteninterpreted incorrectly as depth related; hence, for this and other reasons, depth determinations can be grossly in error. Should be used in conjunction with other methods, i.e., seismic.
APPENDIX E, Cont'd.Geophysical MethodBasic MeasurementApplicationAdvantagesLimitationsSurface (Continued)Acoustic (resonance)Amplitude ofacoustically coupled sound waves originating in an air- filled cavityTraces (on ground surface)lateral extent of cavitiesRapid and reliable method. Interpretation relatively straightforward. Equipment readily availableMust have access to some cavity opening. Still inexperimental stage - limits not fully establishedGround penetratingradar(GPR)Travel time andamplitude of a reflected electromagnetic waveRapidly profiles layeringconditions. Stratification, dip, water table, and presence of many types of anomalies can be determinedVery rapid method for shallow siteinvestigations. On line digital data processing can yield
"on site"look. Variable density display highly effectiveTransmitted signal rapidly attenuated by water. Severely limits depth of penetration. Multiple reflections can complicate data interpretation.
Generally performs poorly in clay-rich sediments.GravityVariations ingravitational fieldDetects anticlinal structures,buried ridges, salt domes, faults, and cavitiesProvided extreme care isexercised in establishing gravitational references, reasonably accurate results can be obtainedRequires specialized personnel. Anything havingmass can influence data (buildings, automobiles, etc).
Data reduction and interpretation are complex.
Topography and strata density influence data.MagneticVariations of earth
'smagnetic fieldDetermines presence andlocation of magnetic or ferrous materials in the subsurface. Locates ore bodiesMinute quantities of magneticmaterials are detectableOnly useful for locating magnetic materials. Interpretation highly specialized. Calibration on site extremely critical. Presence of any ferrous objects near the magnetometer influences data.Uphole/downhole (seismic)Vertical travel time ofcompressional and/or shear wavesVelocity determination ofvertical P- and/or S-waves.
Identification of low-velocity
zonesRapid technique useful to definelow- velocity strata. Interpretation straightforwardCare must be exercised to prevent undesirableinfluence of grouting or casing.Crosshole (seismic)Horizontal travel time ofcompressional and/or shear wavesVelocity determination ofhorizontal P- and/or S-waves.
Elastic characteristics of sub- surface strata can be calculated.Generally accepted as producingreliable results. Detects low- velocity zones provided borehole spacing not excessive.Careful planning with regard to borehole spacingbased upon geologic and other seismic data an absolute necessit
y. Snell
's law of refraction must beapplied to establish zoning. A borehole deviation survey must be run. Requires highly experienced personnel. Repeatable source required.Boreholespontaneous potentialNatural earth potentialCorrelates deposits, locateswater resources, studies rock deformation, assesses permeability, and determines groundwater salinity
.Widely used, economical tool. Particularly useful in the identification of highly porous strata (sand, etc.).Log must be run in a fluid filled, uncased boring. Notall influences on potentials are known.
APPENDIX E, Cont
'd.Geophysical MethodBasic MeasurementApplicationAdvantagesLimitationsBorehole (Continued)Single-point resistivityStrata electricalresistance adjacent to a single electrodeIn conjunction withspontaneous potential, correlates strata and locates porous materialsWidely used, economical tool. Logobtained simultaneous with spontaneous potentialStrata resistivity difficult to obtain. Log must be run ina fluid filled, uncased boring. Influenced by drill fluid.Long and short-normal resistivityNear-hole electricalresistanceMeasures resistivity within aradius of 40 to 165 cm (16 to
64 in.)Widely used, economical toolInfluenced by drill fluid invasion. Log must be run in afluid filled, uncased boring.Lateral resistivityFar-hole electricalresistanceMeasures resistivity within aradius of 6 m (20 ft)Less drill fluid invasion influenceLog must be run in a fluid filled, uncased boring. Investigation radius limited in low moisture strata.Induction resistivityFar-hole electricalresistanceMeasures resistivity in air- oroil-filled holesLog can be run in a nonconductivecasingLarge, heavy tool.Borehole imagery(acoustic)Sonic image ofborehole wallDetects cavities, joints, fractures in borehole wall.
Determines attitude (strike and dip) of structures.Useful in examining casinginterior. Graphic display of images. Fluid clarity immaterial.Highly experienced operator required. Slow log toobtain. Probe awkward and delicate. Continuous sonic (3-D) velocityTime of arrival of P-and S-waves in high- velocity materialsDetermines velocity of P- andS-waves in near vicinity of borehole. Potentially useful for cavity and fracture detection. Modulus determinations. Sometimes S-wave velocities are inferred from P-wave velocity
.Widely used method. Rapid andrelatively economical. Variable density display generally impressive. Discontinuities in strata detectableShear wave velocity definition questionable inunconsolidated materials and soft sedimentary ro cks. Only P-wave velocities greater than 1500 m/s (5,000
ft/s) can be determined.Natural gammaradiationNatural radioactivityLithology, correlation ofstrata, may be used to infer permeability. Locates clay strata and radioactive minerals.Widely used, technically simple tooperate and interpret.Borehole effects, slow logging speed, cannot directlyidentify fluid, rock type, or porosity. Assumes clay minerals contain potassium-40 isotope.
APPENDIX E, Cont
'd.Geophysical MethodBasic MeasurementApplicationAdvantagesLimitationsBorehole (Continued)Gamma-gammadensityElectron densityDetermines rock density ofsubsurface strata.Widely used. Can be applied toquantitative analyses of engineering properties. Can provide porosity.Borehole effects, calibration, source intensity,chemical variation in strata affect measurement precision. Radioactive source hazard.Neutron porosityHydrogen contentMoisture content (abovewater table), total porosity (below water table)Continuous measurement ofporosity. Useful in hydrology and engineering property determinations. Widely usedBorehole effects, calibration, source intensity, boundwater, all affect measurement precision. Radioactive source hazard.Neutron activationNeutron captureConcentration of selectedradioactive materials in strataDetects elements such as U, Na,Mn. Used to determine oil-water contact (oil industry) and in prospecting for minerals (Al, Cu)Source intensity, presence of two or more elementshaving similar radiation energy affect data.Borehole magneticNuclear precessionDeposition, sequence, andage of strataDistinguishes ages of lithologicallyidentical strataEarth field reversal intervals under study. Still subjectof research.Mechanical caliperDiameter of boreholeMeasures borehole diameterUseful in a wet or dry holeMust be recalibrated for each run. Averages3 diameters.
APPENDIX E, Cont
'd.Geophysical MethodBasic MeasurementApplicationAdvantagesLimitationsBorehole (Continued)Acoustic caliperSonic rangingMeasures borehole diameter.Large range. Useful with highlyirregular shapesRequires fluid filled hole and accurate positioning.TemperatureTemperatureMeasures temperature offluids and borehole sidewalls.
Detects zones of inflow or fluid loss .Rapid, economical, and generallyaccurateNone of importance.Fluid resistivityFluid electricalresistanceWater-quality determinationsand auxiliary log for rock resistivity.Economical toolBorehole fluid must be same as groundwater.TracersDirection of fluid flowDetermines direction of fluidflow.EconomicalEnvironmental considerations often preclude use ofradioactive tracers.Flowmeter Fluid velocity andquantityDetermines velocity ofsubsurface fluid flow and, in most cases, quantity of flow.Interpretation is simple.Impeller flowmeters usually cannot measure flows lessthan 1 to 1.7 cm/s (2 - 3 ft/min).Borehole dipmeterSidewall resistivityProvides strike and dip ofbedding planes. Also used for fracture detection.Useful in determining informationon the location and orientation of primary sedimentary structures over a wide variety of hole conditions.Expensive log to make. Computer analysis ofinformation needed for maximum benefit.Downhole flow meterFlow across theboreholeDetermines the rate and direction of groundwater flowA reliable, cost effective methodto determine lateral foundation leakage under concrete structuresAssumes flow not influenced by emplacement ofborehole.
APPENDIX FIN SITU TESTING METHODSTable F-1 In Situ Tests for Rock and Soil (adapted from EM 1110-1-1804, Department of the Army, 1984)Applicability toPurpose of TestType of TestSoilRock Shear strengthStandard penetration test (SPT)Field vane shear Cone penetrometer test (CPT)
Direct shear Plate bearing or jacking Borehole direct shear bPressuremeter bUniaxial compressive bBorehole jacking b X
X
X
X
X
X X a X X
XBearing capacityPlate bearingStandard penetration X X X aStress conditionsMass deformabilityHydraulic fracturingPressuremeter Overcoring Flatjack Uniaxial (tunnel) jacking Borehole jacking bChamber (gallery) pressure bGeophysical (refraction)
Pressuremeter or dilatometer Plate bearing Standard penetration Uniaxial (tunnel) jacking Borehole jacking bChamber (gallery) pressure b X
X X X X
X
X
X X X a X
X
X
X
X X X a X X X
XRelative densityLiquefaction susceptibilityStandard penetrationIn situ samplingStandard penetrationCone penetration test (CPT)
Shear wave velocity (v s)X X X X
X a Primarily for clay shales, badly decomposed, or moderately soft ro cks, and rock with soft seams.
b Less frequently used.
APPENDIX F, Cont
'd.Table F-2In Situ Tests to Determine Shear Strength (adapted from EM 1110-1-1804, Department of the Army, 1984)Test ForRemarksSoilsRocksStandardpenetrationXUse as index test only for strength. Developlocal correlations. Unconfined compressive strength in tsf is often 1/6 to 1/8 of N-valueDirect shearXXExpensive; use when representativeundisturbed samples cannot be obtainedField vane shearXUse strength reduction factor Plate bearingXXEvaluate consolidation effects that may occurduring testUniaxialcompressionXPrimarily for weak rock; expensive since severalsizes of specimens must be tested Conepenetration test (CPT)XConsolidated undrained strength of clays; requires estimate of bearingfactor, N cTable F-3 In Situ Tests to Determine Stress Conditions (adapted from EM 1110-1- 1804, Department of the Army, 1984)TestSoilsRocksRemarksHydraulic fracturingXOnly for normally consolidated or slightlyconsolidated soilsHydraulic fracturingXStress measurements in deep holes for tunnelsVane shearXOnly for recently compacted clays, siltsand fine sands (see Blight, 1974, for details and limitations)OvercoringtechniquesXUsually limited to shallow depth in rockFlatjacksXUniaxial(tunnel) jackingXXMay be useful for measuring lateral stresses in clay shales and rocks, also in soilsBlight , G.E.
" Indirect Determination of in Situ Stress Ratios in Particulate Materials, " Proceedings of a Speciality Conference,Subsurface Explorations for Underground Excavation and Heavy Construction. American Society of Civil Engineers, New York,1974.
APPENDIX F, Cont
'd. Table F-4In Situ Tests to Determine Deformation Characteristics(adapted from EM 1110-1-1804, Department of the Army,
1984) Test ForRemarksSoilsRocksGeophysicalrefraction, Cross-hole and downholeXXFor determining dynamic Young
's Modulus, E, at the small strain induced bytest procedure. Test values for E must be reduced to values corresponding to strain levels induced by structure or seismic loads.PressuremeterXXConsider test as possibly useful but not fully evaluated. For soils and softrocks, shales, et
c. Chamber testXX
Uniaxial (tunnel)jacking XXFlatjackingX
Borehole jackor dilatometer XPlate bearingX
Plate bearingStandardpenetration XXUsed in empirical correlations to estimate settlement of footings; a number ofrelationships are published in the literature to relate penetration test blow counts to settlement potential.
APPENDIX GInstruments for Measuring Groundwater Pressure Instrument TypeAdvantagesLimitations
1aObservation wellCan be installed by drillers without participation ofgeotechnical personnel.Provides undesirable vertical connection between strata and istherefore often misleading; should rarely be used.Open standpipe piezometerReliable. Long successful performance record.Self-de-airing if inside diameter of standpipe is adequate.
Integrity of seal can be checked after installation. Can be converted to diaphragm piezometer. Can be used for sampling groundwater. Can be used to measure permeability.Long time lag. Subject to damage by construction equipment andby vertical compression of soil around standpipe. Extension of standpipe through embankment fill interrupts construction and causes inferior compaction. Porous filter can plug owing to repeated water inflow and outflow. Push-in versions subject to several potential errors.Twin-tube hydraulic piezometerInaccessible components have no moving parts. Reliable.Long successful performance record. When installed in fill, integrity can be checked after installation. Piezometer cavity can be flushed. Can be used to measure permeability.Application generally limited to long-term monitoring of pore waterpressure in embankment dams. Elaborate terminal arrangements needed. Tubing must not be significantly above minimum piezometric elevation. periodic flushing may be required. Attention to many details is necessary.Pneumatic piezometerShort time lag. Calibrated part of system accessible.Minimum interference to construction: level of tubes and readout independent of level of tip. No freezing problems.Attention must be paid to many details when making selection.Push-in versions subject to several potential errors.Vibrating wire piezometerEasy to read. Short time lag. Minimum interference toconstruction: level of lead wires and readout independent of level of tip. Lead wire effects minimal. Can be used to read negative pore water pressures. No freezing problems.Special manufacturing techniques required to minimize zero drift.Need for lightning protection should be evaluated. Push-in version subject to several potential errors.Unbonded electrical resistance piezometerEasy to read. Short time lag. Minimum interference toconstruction: level of lead wires and readout independent of level of tip. Can be used to read negative pore water pressures. No freezing problems. Provides temperature measurement. Some types suitable for dynamic measurements.Low electrical output. Lead wire effects. Errors caused by moistureand electrical connections are possible. Need for lightning protection should be evaluated.
a Diaphragm piezometer readings indicate the head above the piezometer, and the elevation of the piezometer must be measured or estimated if piezometric elevation is required. All diaphragmpiezometers, except those provided with a vent to the atmosphere, are sensitive to barometric pressure changes.
APPENDIX G, Cont
'd.Instrument TypeAdvantagesLimitations aBonded electrical resistance piezometerEasy to read. Short time lag. Minimum interference toconstruction: level of lead wires and readout independent of level of tip. Suitable for dynamic measurements. Can be used to read negative pore water pressures. No freezing problems.Low electrical output. Lead wire effects. Errors caused by moisture,temperature, and electrical connections are possible. Long-term stability uncertain. Need for lightning protection should be evaluated.
Push-in version subject to several potential errors.Multipoint piezometer, with packersProvides detailed pressure-depth measurements.Can be installed in horizontal or upward boreholes.
Other advantages depend on type of piezometer: see above in table.Limited number of measurement points. Other limitations depend ontype of piezometer: see above in table.Multipoint piezometer, surrounded with groutProvides detailed pressure-depth measurements.Simple installation procedure. Other advantages depend on type of piezometer: See above in table.Limited number of measurement points. Applicable only in uniform clayof known properties. Difficult to ensure in-place grout of known properties. Other limitations depend on type of piezometer: see above in table.Multipoint push-in piezometerProvides detailed pressure-depth measurements.Simple installation procedure. Other advantages depend on type of piezometer: See above in table.Limited number of measurement points. Subject to several potentialerrors. Other limitations depend on type of piezometer: see above in table.Multipoint piezometer, with movable probeProvides detailed pressure-depth measurements.Unlimited number of measurement points. Allows determination of permeability. Calibrated part of system accessible. Great depth capability.
Westbay Instruments system can be used for sampling groundwater and can be combined with inclinometer casing.Complex installation procedure. Periodic manual readings only.
REGULATORY ANALYSISA separate regulatory analysis was not prepared for this regulatory guide. The regulatoryanalysis prepared for Draft Regulatory Guide DG-1101, "Site Investigations for Foundations of Nuclear Power Plants" (February 2001), provides the regulatory basis for this regulatory guide as well. DG-1101 was issued for public comment as the draft of this present regulatory guide. A
copy of the regulatory analysis is available for inspection and copying for a fee at the U.S.
Nuclear Regulatory Commission Public Document Room, 11555 Rockville Pike, Rockville, MD; the PDR's mailing address is USNRC PDR, Washington, DC 20555; telephone (301)415-
4737 or 1-(800)397-4209; fax (301)415-3548; e-mail <PDR@NRC.GOV>.