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Soil Improvement Case 1 Zones of Soil Improvment Soil Improvement Case 2 Figure 8.25: Cross Section of the Columbia River Levee with Two Cases of Soil Improvement. The numerical FLAC analysis was performed using the Aeropuerto time history with the water stage representing the 100-year flood. The motion was scaled to 0.10g, consistent with the peak horizontal acceleration computed by SHAKE91 at the elevation corresponding to the base of the FLAC model. The maximum horizontal deformations obtained in this analysis are listed in Table 8.21, along with the values obtained without soil improvement from Table 8.18. The displacements computed for the M 8.5 earthquake are well within tolerable limits for most bridges and ancillary components. 185
Table 8.21: Comparison of Predicted Maximum Levee Displacements With and Without Soil Improvement at the 100 yr Flood Stage. METHOD OF CALCULATION MAXIMUM HORIZONTAL RIVERWARD LEVEE DISPLACEMENT (cm) Without With Case 1 With Case 2 Soil Improvement Soil Improvement Soil Improvement Newmark 7 0 0 Makdisi and Seed 100 N/A N/A Bracketed Intensity 1 0 0 Results of the Parametric Study 30 2 < 1 Numerical Model: N. Levee Crest 16 < 1 < 1 Negative horizontal displacements represent movement toward the river and negative vertical displacements signify settlement. N/A denotes peak acceleration at the depth of interest is less than the yield acceleration for deep-seated, riverward slides (i.e., the deformation is 0 cm). 8.10 SUMMARY AND CONCLUSIONS The significant consequences associated with the failure of the Columbia River levee in the vicinity of the Interstate 5 and 205 bridges and Marine Drive provided the impetus for this thorough multi-hazard stability investigation. Standard of practice methods were used in conjunction with more sophisticated numerical models to assess the overall stability of the levee under static and dynamic loading conditions. The primary objectives of this investigation included: (1) evaluating the static stability of the levee at three different river stages; (2) assessing the seismic stability of the levee at the aforementioned water levels; (3) evaluating the potential extent of earthquake-induced deformations of the levee, and (4) indicating, in a general sense, the effectiveness of soil improvement for reducing seismically-induced deformations of the levee. The following conclusions can be drawn based on this investigation. Under static conditions, the levee appears to be stable at all sections with the river stage at the 100-year flood elevation or lower (elevation 8.8 m). However, landward failures due to high seepage forces were estimated to occur if the river was to reach the crest of the levee. The liquefaction hazard was considered to be minimal for a magnitude 6.2 earthquake however the generation of partial excess pore pressures combined with the higher intensity of ground motions produced permanent deformations that were similar to, or larger than those estimated for the larger scenario earthquakes. Conversely, the liquefaction hazard was greater for the distant, larger earthquakes but the destructiveness is limited somewhat by the low intensity of the motions. The silt rich soils in the levee and foundation are considered liquefiable based on cyclic laboratory tests performed on specimens from the site. Under worst-case conditions, the levee is estimated to experience displacements of approximately 0.6 to 0.9 m (2-3 ft) based on the numerical modeling. Simplified chart solutions for estimating seismically-induced deformations provided reasonable values from the standpoint of a preliminary screening for liquefaction hazards. It was 186
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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
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The models were instrumented with a
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The model uses an explicit method,
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A simplification was made in the mo
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permanent earthquake displacements)
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7.0 DEFORMATION ANALYSIS OF EMBANKM
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engineers; (2) requisite input incl
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π g 2 a t I a 2 dt (7-1) The A
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10 1 Bracketed Intensity (m/s) 0.1
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7.3 PARAMETRIC STUDY A well-validat
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the rigid body methods. The point a
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0.4 Acceleration (g) 0.2 0 -0.2 -0.
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Embankment Height (m) Depth of Liqu
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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 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: applications (DDC, closely spaced v
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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