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Figure 8.12: Variation of G/G max versus λ versus Cyclic Shear Strain for Cohesionless Soils (after Seed et al. 1984) The SHAKE91 program utilizes initial estimates of modulus and damping ratio to calculate a maximum shear strain in each layer. This maximum strain is multiplied by a reduction factor, (n), to produce an average strain, or equivalent uniform strain, in each layer. The value of (n), defined as the ratio of the equivalent uniform strain divided by the maximum calculated strain, is typically set between 0.40 to 0.75 depending on the characteristics of the bedrock input motion, or simply as a function of the magnitude of earthquake motions being modeled. The following equation has been recommended to estimate this ratio (Idriss and Sun 1992): 159
n ( M 10 1) (8-1) where M is the magnitude of the earthquake. The equivalent uniform shear strain is used to compare the original modulus and damping ratio with values obtained from the curves of Figures 8.11 and 8.12. The iterations continue until both the modulus and damping ratio used to compute strains are compatible with the user-defined curves (less than about 1% error), or until the specified number of iterations is reached. The acceleration time histories (Table 8.5) were input at the interface between the Sandy River mudstone and Troutdale gravels at elevation -80 m. 8.5.2 Results of the Dynamic Soil Response Analysis For each acceleration time history, SHAKE91 was used to compute: (1) the acceleration response spectrum on rock to compare against the target spectra generated by the attenuation relationships, (2) the PGA at the top of each defined layer (34 total) to create a profile of PGA versus elevation, (3) equivalent uniform shear stresses for use in the liquefaction analyses, and (4) acceleration time histories for use in the Newmark analyses. Figures 8.13 to 8.16 show the results for each SHAKE91 analysis for the Long Valley Dam (Mammoth Lakes) time history. 1.50 1.40 (5% Damping) 1.30 1.20 1.10 Spectral Acceleration (g) 1.00 0.90 0.80 0.70 0.60 0.50 0.40 0.30 0.20 0.10 0.00 0 0.5 1 1.5 2 2.5 Period (sec) 3 Figure 8:13: Response Spectrum for Ground Surface Motions at Location 4E (Scaled Long Valley Dam Bedrock Motion) 160
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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
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5.3 DESIGN OF SOIL MITIGATION The d
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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 and 168: 154 Table 8.5: Selected Acceleratio
Page 169 and 170: Spectral Acceleration (g) 1.50 1.40
Page 171: with the calculated equivalent unif
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
Page 219 and 220: Schnabel, P., J. Lysmer, and H.B. S
Page 221 and 222: Sun, I.H. and I.M. Idriss. (1992).
Page 223:
Youd, T.L. and C.F. Jones. (1993).
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