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USGS Award Number G16AP00003 REDUCING UNCERTAINTY OF LIQUEFACTION HAZARD ASSESSMENTS IN AGED SOIL DEPOSITS Final Report to the United States Geological Survey By: Barnabas Bwambale and Ronald D. Andrus Glenn Department of Civil Engineering Clemson University Lowry Hall, Box 340911 Clemson, South Carolina 29634-0911 USA Telephone: (864) 656-0488 Fax: (864) 656-2670 E-mail: [email protected] February 18, 2017 Research supported by the United States Geological Survey (USGS), Department of the Interior, under USGS award number G16AP00003. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the opinions or policies of the U.S. Geological Survey. Mention of trade names or commercial products does not constitute their endorsement by the U.S. Geological Survey. ii USGS Award Number G16AP00003 REDUCING UNCERTAINTY OF LIQUEFACTION HAZARD ASSESSMENTS IN AGED SOIL DEPOSITS Final Report to the United States Geological Survey by Barnabas Bwambale and Ronald D. Andrus Glenn Department of Civil Engineering Clemson University Lowry Hall, Box 340911 Clemson, South Carolina 29634-0911 USA Telephone: (864) 656-0488 Fax: (864) 656-2670 E-mail: [email protected] ABSTRACT The influence of aging processes (or simply age) on liquefaction resistance of Holocene and Pleistocene soils near Christchurch, New Zealand is evaluated in this report. Many Holocene alluvial and marine deposits in and around Christchurch experienced minor to severe liquefaction during the 2010-2011 Canterbury earthquake sequence. Liquefaction and permanent ground deformations were most severe in the city during the 22 February 2011 event. Permanent horizontal ground displacements up to 0.35 m also occurred at several locations in moderately sloping Pleistocene loess-colluvium in the Port Hills area, but no sand/silt boil has been connected to those deposits. Computed ratios of measured small-strain shear wave velocity to estimated small-strain shear wave velocity based on penetration resistance (MEVR) determined for the critical layers in Holocene deposits in four different areas agree well with the study by McGann et al. and are similar to ratios of about 1.0 computed for recently liquefied deposits in other areas of the world. On the other hand, MEVR values determined for the loess-colluvium typically range from 1.0 to 5.0, with the zone of lowest values occurring below the groundwater table and above a depth of 6.5 m. Deposit resistance correction factors to account for aging processes (KDR) determined for the Holocene and Pleistocene deposits are in good agreement with the MEVR-based relationship developed by Hayati and Andrus from a global database. However, average KDR determined for the loess-colluvium is significantly greater than values suggested by their time-based relationship. These findings support the use of MEVR and KDR for accurate site-specific liquefaction assessment in aged soil deposits. iii ACKNOWLEDGMENTS This research was supported by the United States Geological Survey (USGS), Department of the Interior under USGS Award No. G16AP00003, with Ronald D. Andrus as Principal Investigator. The support of the USGS is greatly appreciated. It is based in part on maps and data extracted from the Canterbury Geotechnical Database (https://canterburygeotechnicaldatabase.projectorbit.com/), which were prepared and/or compiled for the Earthquake Commission (EQC) to assist in assessing insurance claims made under the Earthquake Commission Act 1993. The source maps and data were not intended for any other purpose. EQC and its engineers, Tonkin and Taylor, have no liability for any use of the maps and data or for the consequences of any person relying on them in any way. This research was initiated while the second author was a Visiting Academic at the University of Canterbury in Christchurch, New Zealand. The authors gratefully acknowledge Misko Cubrinovski for graciously hosting the second author’s visit, for discussing liquefaction in Christchurch, and for reviewing a draft of the section on “Liquefaction Resistance of Holocene Alluvial and Marine Soils”. The authors also gratefully acknowledge David Bell for spending time discussing ground failures in the Port Hills loess-colluvium and for sharing reports. The kindness and help of many other faculty and staff at the University of Canterbury are sincerely appreciated. The authors also sincerely thank Russell Green and Brett Maurer of Virginia Polytechnic Institute and State University for kindly providing information on the Kaiapoi cone penetration tests. Joshua Gathro, a graduate student at Clemson University, provided reviews of various drafts of this work. iv TABLE OF CONTENTS TITLE PAGE ……………………………………………………………………………………i ABSTRACT ................................................................................................................................ iii ACKNOWLEDGMENTS ........................................................................................................... iv INTRODUCTION ........................................................................................................................ 1 LIQUEFACTION RESISTANCE OF HOLOCENE ALLUVIAL AND MARINE SOILS ....... 4 Introduction .............................................................................................................................. 4 KDR from Laboratory Cyclic Tests ............................................................................................ 6 KDR from Laboratory and Field Tests ....................................................................................... 8 KDR from Field Tests ............................................................................................................... 12 Measured to Estimated Shear Wave Velocity Ratio .............................................................. 15 LIQUEFACTION RESISTANCE OF PLEISTOCENE LOESS-COLLUVIUM ...................... 16 Introduction ............................................................................................................................ 16 Geologic and Seismologic Setting .......................................................................................... 16 Field Data ............................................................................................................................... 20 Measured to Estimated Shear Wave Velocity Ratio .............................................................. 22 Liquefaction Potential and Back-Calculated Correction Factor ............................................. 24 Comparison with Relationships by Hayati and Andrus .......................................................... 25 CONCLUSIONS ........................................................................................................................ 29 REFERENCES ........................................................................................................................... 30 APPENDIX A—KILMORE STREET SITE FIELD DATA ..................................................... 36 APPENDIX B—GAINSBOROUGH RESERVE SITE FIELD DATA .................................... 40 APPENDIX C—RICCARTON ROAD SITE FIELD DATA.................................................... 45 APPENDIX D—KAIAPOI AREA FIELD DATA .................................................................... 49 APPENDIX E—PORT HILLS AREA FIELD DATA .............................................................. 60 v INTRODUCTION The simplified procedure originally proposed by Seed and Idriss (1971) is commonly used to evaluate liquefaction potential of soil. As discussed by Youd et al. (2001), this procedure involves estimation of the seismic demand on a soil layer, expressed in terms of the cyclic stress ratio (CSR), and the capacity of the soil to resist liquefaction, expressed in terms of the cyclic resistance ratio (CRR). Field methods, such as the standard penetration test (SPT), the cone penetration test (CPT), and shear wave velocity (VS) are typically used for estimating CRR because of the complexities associated with undisturbed sampling and laboratory testing. A limitation of commonly used charts for estimating CRR is that they are based on predominantly field case histories involving soil deposits less than a few thousand years old and there are no generally accepted guidelines for applying them to older deposits (Youd et al. 2001; Idriss and Boulanger 2008; NASEM 2016). Although older soils generally perform better during strong earthquake shaking, several cases of Holocene liquefaction-induced ground failure occurring in Pleistocene sediments have been reported (e.g., Andrus and Youd 1987; Martin and Clough 1990; Lewis et al. 1999; Blum et al. 2000; Andrus et al. 2004a; Tuttle et al. 2006; Porat et al. 2007; Hayati and Andrus 2008; Heidari and Andrus 2010, 2012; Li et al. 2013; Jacoby et al. 2015). For example, liquefaction- induced ground failures occurred in Pleistocene beach deposits during the 1886 Charleston, South Carolina earthquake (Martin and Clough 1990; Lewis et al. 1999; Heidari and Andrus 2012). Another example is the liquefaction and lateral spreading that occurred in Pleistocene distal alluvial fan sediments during the 1983 Borah Peak, Idaho earthquake (Andrus and Youd 1987; Andrus et al. 2004a). It is thus important to assess the liquefaction hazard of Pleistocene sediment. Currently, the influence of processes that occur in soil over time (or simply age) on resistance to liquefaction is not well understood and uncertainty is generally