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8.4.3 Crustal Bedrock Ground Motions Attenuation relationships by Abrahamson and Silva (1997), Boore et al. (1997), and Campbell (1997) were used to determine the spectral content of the crustal earthquake motions. The recommended design level earthquake having a roughly 500 year return period is M w 6.2 (Geomatrix 1995). The M w 6.2 is consistent with other seismic hazard studies; however, it has been specified here to occur on the East Bank fault instead of occurring as a floating “random source.” Given the close proximity of the East Bank fault to the levee site, the attenuation relationships yielded PGA rock values that were higher than those recommended by the USGS (1996) and Geomatrix (1995) for an event with a 475-year return period. A deterministic evaluation of the regional seismic hazard analysis by Wong et al. (2000) estimated that the East Bank fault is capable of M w 6.8 earthquakes. This magnitude was rounded up to M w 7.0 to represent an earthquake with a 2% probability of exceedance in 50 years. This assumption was validated by the crustal attenuation relationships which yielded an average PGA rock value of 0.38g, consistent with the values given by Geomatrix (1995) and the USGS (1996) for a uniform hazard study earthquake with a 2,475-year return period. The PGA rock values for each attenuation relationship along with the respective averages for a M w 6.2 and M w 7.0 crustal event are shown in Table 8.4. Numerous acceleration response spectra were evaluated in order to select the time histories that most closely matched the target spectra, PGA, duration, source-to-site distance, and magnitude for the crustal event. Selected records from the M w 6.2, 1980 Mammoth Lakes earthquake (Long Valley Dam station) and the M w 6.4, 1971 San Fernando earthquake (Lake Hughes No. 4 station) were determined to best match the M w 6.2 target spectra, while motions from the M w 7.0, 1994 Northridge earthquake (L.A. City Terrace station) and the M w 7.0, 1989 Loma Prieta earthquake (U.C. Santa Cruz station) were chosen for the M w 7.0 event, as shown in Figure 8.8 and Figure 8.9. These design earthquakes were scaled to PGA rock values of 0.29g and 0.38g, respectively, for the dynamic ground motion analyses. 8.5 DYNAMIC SOIL RESPONSE ANALYSES Dynamic soil response analyses were conducted to compute both the PGA values in the soil versus depth, and the cyclic shear stresses induced as a result of strong ground shaking. As previously mentioned, a shear wave velocity profile was constructed with data collected from the seismic cone test at the site (Figure 8.10). Shear wave velocities in the soils at depths below that of the CPT sounding (elevation -15 m (-49 ft) were estimated using shear wave data collected from a previous exploration conducted at PDX (Wong and Silva 1993). Eight earthquake time histories were used in the analysis in order to evaluate the sensitivity of the soils to various recorded ground motions. The computer program SHAKE91 (Idriss and Sun 1992) was used to perform one-dimensional, dynamic soil response analyses. 155
Spectral Acceleration (g) 1.50 1.40 1.30 1.20 1.10 1.00 0.90 0.80 0.70 0.60 0.50 (5% Damping) Magnitude 6.2 Target Spectrum Scaled Lake Hughes #4 Ground Motion Scaled Long Valley Dam Ground Motion 0.40 0.30 0.20 0.10 0.00 0 0.5 1 1.5 2 2.5 Period (sec) 3 Figure 8.8: Long Valley Dam and Lake Hughes #4 (Scaled PGA = 0.29g) Response Spectra Compared to the Magnitude 6.2 East Bank Crustal Earthquake on Rock Spectral Acceleration (g) 1.50 1.40 1.30 1.20 1.10 1.00 0.90 0.80 0.70 0.60 0.50 (5% Damping) Magnitude 7.0 Target Spectrum Scaled LA City Terrace Ground Motion Scaled UCSC Ground Motion 0.40 0.30 0.20 0.10 0.00 0 0.5 1 1.5 2 2.5 Period (sec) 3 Figure 8.9: UCSC and LA City Terrace (Scaled PGA = 0.38g) Response Spectra Compared to the Magnitude 7.0 East Bank Crustal Earthquake on Rock 156
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ASSESSMENT AND MITIGATION OF LIQUEF
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ACKNOWLEDGMENTS The authors would l
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ASSESSMENT AND MITIGATION OF LIQUEF
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8.0 HAZARD EVALUATION AND DEVELOPME
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LIST OF FIGURES Figure 1.1: ODOT’
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Figure 8.8: Long Valley Dam and Lak
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Design of a given component shall l
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Liquefaction Mitigation Procedure G
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Pacific Northwest also are summariz
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2.0 OVERVIEW OF LIQUEFACTION-INDUCE
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oughly 50 centimeters, with numerou
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supported bridges along the Seward
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Another area of extensive bridge da
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Nineteen bridges were also damaged
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1. No foundation failures were obse
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piles supporting the fourth pier, l
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Figure 2.17: Observed Pile Deformat
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Figure 2.19: Damage from the 1906 S
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Figure 2.22: Ground Deformations Ne
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induced ground displacement was the
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Well-documented case histories of t
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Similar damage to pile foundations
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Examples of acceptable bridge found
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Numerous investigations of liquefac
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3.0 EVALUATION OF LIQUEFACTION SUSC
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The evaluation of liquefaction haza
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Table 3.1: Estimated Susceptibility
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movements, or localized ground disp
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Shear wave velocities can now be ob
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3.4 LIQUEFACTION RESISTANCE: EMPIRI
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Figure 3.1: Range of r d Values for
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The earthquake-induced shearing str
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drill rod during hammer impact. In
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Figure 3.5: Minimum Values for K σ
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3.4.2.2.1 CPT Method Developed by R
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1. Sensitive, fine grained 6. Sands
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Figure 3.9: CPT-Based Curves for Va
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CRR where: q c 2 3 0.00128 0.0
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Tacoma, Washington (Dickenson and B
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Table 3.8: Influence of OCR on the
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Figure 3.13: Influence of Fines Con
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Gravel Sand Figure 3.16: Relationsh
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FS L > 1.4: Excess pore pressure ge
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The post-liquefaction strength of s
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Figure 4.3: Undrained Critical Stre
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4.3 INTRODUCTION TO MODES OF FAILUR
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Figure 4.5: (a) Relationship betwee
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not available for many case studies
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provided to give the recommended ra
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Figure 4.8: Overview of EPOLLS Mode
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Figure 4.10: Model of Hypothetical
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4.5.2 Advanced Numerical Modeling o
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Figure 4.12: Post Volumetric Shear
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The relationship shown in Figure 4.
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A third type of failure is shown in
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Table 5.1: Liquefaction Remediation
Page 118 and 119: 5.3 DESIGN OF SOIL MITIGATION The d
Page 120 and 121: soil improvement guidelines state t
Page 122 and 123: The models were instrumented with a
Page 124 and 125: The model uses an explicit method,
Page 126 and 127: A simplification was made in the mo
Page 128 and 129: permanent earthquake displacements)
Page 130 and 131: 7.0 DEFORMATION ANALYSIS OF EMBANKM
Page 132 and 133: engineers; (2) requisite input incl
Page 134 and 135: π g 2 a t I a 2 dt (7-1) The A
Page 136 and 137: 10 1 Bracketed Intensity (m/s) 0.1
Page 138 and 139: 7.3 PARAMETRIC STUDY A well-validat
Page 140 and 141: the rigid body methods. The point a
Page 142 and 143: 0.4 Acceleration (g) 0.2 0 -0.2 -0.
Page 144 and 145: Embankment Height (m) Depth of Liqu
Page 146 and 147: 10 1 DISPLACEMENT (m) 0.1 Morgan Hi
Page 148 and 149: 2.0 Embankment Toe Embankment Mid-S
Page 150: suitably reliable estimates of perm
Page 153 and 154: interest. Specifically, the peak be
Page 155 and 156: Flow Chart for Evaluation and Mitig
Page 157 and 158: The deformation evaluations were pe
Page 159 and 160: Portland (a) (b) Figure 8.2: Illust
Page 161 and 162: Figure 8.4: Contours of PGA on Rock
Page 163 and 164: Borehole 4E CPT Hole 4E 26.0' NGVD
Page 165 and 166: 8.4.2 Subduction Zone Bedrock Motio
Page 167: 154 Table 8.5: Selected Acceleratio
Page 171 and 172: with the calculated equivalent unif
Page 173 and 174: n ( M 10 1) (8-1) where M is the
Page 175 and 176: 0.20 0.15 0.10 Acceleration (g) 0.0
Page 177 and 178: 15.0 12.5 10.0 Long Valley Dam Lake
Page 179 and 180: CSR should be modified for the pres
Page 181 and 182: 8.7 EVALUATION OF INITIATION OF LIQ
Page 183 and 184: crest stage Marine Drive 42.5 ft NG
Page 185 and 186: Table 8.9: Fines Content Values Est
Page 187 and 188: large sliding and long-term disrupt
Page 189 and 190: Table 8.12: Deformation Results fro
Page 191 and 192: The earthquake time histories used
Page 193 and 194: North (river) South (land) North To
Page 195 and 196: Table 8.20: Riverward Deformation R
Page 197 and 198: applications (DDC, closely spaced v
Page 199 and 200: Table 8.21: Comparison of Predicted
Page 202 and 203: 9.0 SUMMARY AND CONCLUSIONS Recent
Page 204: dewatering may be warranted. Additi
Page 207 and 208: Bardet, J.P. (1990). “LINOS - A N
Page 209 and 210: California Division of Mines and Ge
Page 211 and 212: Fujii, S., M. Cubrinovski, K. Tokim
Page 213 and 214: Ishihara, K. and M. Cubrinovski. (1
Page 215 and 216: Liu, A.H. and J.P. Stewart. (1999).
Page 217 and 218: Oregon Department of Transportation
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Schnabel, P., J. Lysmer, and H.B. S
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Sun, I.H. and I.M. Idriss. (1992).
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Youd, T.L. and C.F. Jones. (1993).
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