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provided to give the recommended ranges of input values for which the predicted displacements have been verified by comparison with the case-history data. Figure 4.7: Comparison of Computed Lateral Spread Displacements with Observed Displacements (Youd et. al., 1999) Table 4.3: Ranges of Input Values for Independent Variables for Which Predicted Results are Verified by Case History Observations (Bartlett and Youd 1992) INPUT FACTOR RANGE OF VALUES IN CASE HISTORY DATABASE Magnitude 6.0 < M < 8.0 Free-Face Ratio (%) 1.0 < W < 20.0 Ground Slope (%) 0.1 < S < 6.0 Thickness of Loose Layer (m) 0.3 < T 15 < 12.0 Fines Content (%) 0.0 < F 15 < 50.0 Mean Grain Size (mm) 0.1 < D50 15 < 1.0 The results of the equation correspond to free-field conditions. Actual displacements near bridges may be less than predicted by the model, depending on the ability of the foundation to resist deformation. This reduction should not be anticipated unless supported by use of validated soil-structure interaction models. The range of verified slope angles is not in the range for most bridge embankments; therefore, the equation should be used to estimate movements away from the slope face which generally does not capture the area of most pronounced failures. 88
4.4.3 EPOLLS Model for Lateral Spread Displacement The most recent model for estimating horizontal displacements is termed EPOLLS – Empirical Prediction of Liquefaction-Induced Lateral Spreading (Rauch and Martin 2000). The model was developed from a database of 71 historical lateral spreads using statistical regression techniques. The model can be used to estimate the average horizontal displacement given site-specific seismological, topographical, and geological parameters. The model has been formulated in three complementary parts: (1) the Regional-EPOLLS component, designed for seismic hazard surveys of geographic regions; (2) the Site-EPOLLS component, which gives improved predictions for site-specific studies; and (3) the Geotechnical-EPOLLS component, which uses additional data from subsurface explorations, thereby reducing uncertainty in the estimated lateral spread displacement. An overview of the EPOLLS model and the predictive equations used are shown in Figure 4.8. As with the method by Youd and others, this model should not be applied for scenarios that are significantly different from those cases used to develop the predictive equation. 4.5 ANALYTICAL METHODS FOR ESTIMATING LATERAL SPREAD DISPLACEMENT The empirical methods for estimating lateral spread displacement are straightforward tools for preliminary hazard screening at bridge sites. Also, the empirical basis for the displacement estimates provides credibility to these methods. The methods are, however, limited in their application to the specific range of earthquakes, source-to-site distances, geological and geotechnical conditions, and topographies from the cases studies employed in the development of the predictive relationships. Most of the lateral spreads were evaluated at free-field sites. These conditions severely limit the application of the empirical methods for bridge sites with embankments and site-specific configurations. In these cases, the empirical approaches can be used only as approximate indicators of lateral spread hazard, and supplementary analysis procedures are required. Common methods of analysis include rigid body mechanics (i.e., the sliding-block methods) and numerical effective stress modeling. 4.5.1 Newmark Sliding Block Model In most applications involving waterfront slopes and embankments, it is necessary to estimate the permanent slope deformations that may occur in response to the cyclic loading. Allowable deformation limits for slopes will reflect the sensitivity of adjacent structures, foundations and other facilities to these soil movements. Enhancements to traditional pseudostatic limit equilibrium methods of embankment analysis have been developed to estimate deformations for soils that do not lose appreciable strength during earthquake shaking (Makdisi and Seed 1978; Ambraseys and Menu 1988; Jibson 1993). These methods are not appropriate for modeling flowtype failures that can be associated with very loose saturated sands (N = 3-5 blows/ft). 89
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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
Page 51 and 52: Numerous investigations of liquefac
Page 53 and 54: 3.0 EVALUATION OF LIQUEFACTION SUSC
Page 55 and 56: The evaluation of liquefaction haza
Page 57 and 58: Table 3.1: Estimated Susceptibility
Page 59 and 60: movements, or localized ground disp
Page 61 and 62: Shear wave velocities can now be ob
Page 63 and 64: 3.4 LIQUEFACTION RESISTANCE: EMPIRI
Page 65 and 66: Figure 3.1: Range of r d Values for
Page 67 and 68: The earthquake-induced shearing str
Page 69 and 70: drill rod during hammer impact. In
Page 71 and 72: Figure 3.5: Minimum Values for K σ
Page 73 and 74: 3.4.2.2.1 CPT Method Developed by R
Page 75 and 76: 1. Sensitive, fine grained 6. Sands
Page 77 and 78: Figure 3.9: CPT-Based Curves for Va
Page 79 and 80: CRR where: q c 2 3 0.00128 0.0
Page 81 and 82: Tacoma, Washington (Dickenson and B
Page 83 and 84: Table 3.8: Influence of OCR on the
Page 85 and 86: Figure 3.13: Influence of Fines Con
Page 87: Gravel Sand Figure 3.16: Relationsh
Page 90 and 91: FS L > 1.4: Excess pore pressure ge
Page 92 and 93: The post-liquefaction strength of s
Page 94 and 95: Figure 4.3: Undrained Critical Stre
Page 96 and 97: 4.3 INTRODUCTION TO MODES OF FAILUR
Page 98 and 99: Figure 4.5: (a) Relationship betwee
Page 100 and 101: not available for many case studies
Page 104 and 105: Figure 4.8: Overview of EPOLLS Mode
Page 106 and 107: Figure 4.10: Model of Hypothetical
Page 108 and 109: 4.5.2 Advanced Numerical Modeling o
Page 110 and 111: Figure 4.12: Post Volumetric Shear
Page 112 and 113: The relationship shown in Figure 4.
Page 114 and 115: A third type of failure is shown in
Page 116 and 117: 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
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interest. Specifically, the peak be
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Flow Chart for Evaluation and Mitig
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The deformation evaluations were pe
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Portland (a) (b) Figure 8.2: Illust
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Figure 8.4: Contours of PGA on Rock
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Borehole 4E CPT Hole 4E 26.0' NGVD
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8.4.2 Subduction Zone Bedrock Motio
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154 Table 8.5: Selected Acceleratio
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Spectral Acceleration (g) 1.50 1.40
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with the calculated equivalent unif
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n ( M 10 1) (8-1) where M is the
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0.20 0.15 0.10 Acceleration (g) 0.0
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15.0 12.5 10.0 Long Valley Dam Lake
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CSR should be modified for the pres
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8.7 EVALUATION OF INITIATION OF LIQ
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crest stage Marine Drive 42.5 ft NG
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Table 8.9: Fines Content Values Est
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large sliding and long-term disrupt
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Table 8.12: Deformation Results fro
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The earthquake time histories used
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North (river) South (land) North To
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Table 8.20: Riverward Deformation R
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applications (DDC, closely spaced v
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Table 8.21: Comparison of Predicted
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9.0 SUMMARY AND CONCLUSIONS Recent
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dewatering may be warranted. Additi
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Bardet, J.P. (1990). “LINOS - A N
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California Division of Mines and Ge
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Fujii, S., M. Cubrinovski, K. Tokim
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Ishihara, K. and M. Cubrinovski. (1
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Liu, A.H. and J.P. Stewart. (1999).
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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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