development of a direct test method for dynamically assessing the liquefaction resistance of soils in situ

Copyright by Brady Ray Cox 2006 The Dissertation Committee for Brady Ray Cox Certifies that this is the approved version of the following dissertation: Development of a Direct Test Method for Dynamically Assessing the Liquefaction Resistance of Soils In Situ Committee: Kenneth H. Stokoe II, Supervisor Ellen M. Rathje John L. Tassoulas Clark R. Wilson T. Leslie Youd Development of a Direct Test Method for Dynamically Assessing the Liquefaction Resistance of Soils In Situ by Brady Ray Cox, M.S. Dissertation Presented to the Faculty of the Graduate School of The University of Texas at Austin in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy The University of Texas at Austin May 2006 UMI Number: 3222596 3222596 2006 Copyright 2006 by Cox, Brady Ray UMI Microform Copyright All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. ProQuest Information and Learning Company 300 North Zeeb Road P.O. Box 1346 Ann Arbor, MI 48106-1346 All rights reserved. by ProQuest Information and Learning Company. Dedication To my lovely wife Audrey and my two beautiful daughters Kayla and Savannah To my steadfast parents Clayton and Jerri Lynn To all my family v Acknowledgements I express my deepest gratitude to my advisor, Dr. Kenneth H. Stokoe II. I could not have asked to work with a more talented and enthusiastic individual. He has involved me on many interesting and challenging projects that have allowed me to travel, to meet people in the profession, and to gain knowledge and expertise outside the bounds of my dissertation research. I will forever benefit from these experiences. It has been an honor and a privilege to not only work for a great professor, but also a great man. I am grateful for the help and guidance provided to me by my advisory committee members, Dr. Ellen Rathje, Dr. John L. Tassoulas, Dr. Clark R. Wilson, and Dr. T. Leslie Youd. I have learned a great deal from each of these individuals. I acknowledge and give thanks to the other geotechnical engineering faculty members at The University of Texas, Dr. Gilbert, Dr. Olson, Dr. Tonon, Dr. Wright and Dr. Zornberg. They have made, and will continue to make, this program one of the best in the country. There have been many students and other individual who have helped me during my time at The University of Texas. In particular, I give thanks to Min Jae Jung for keeping me laughing on many long field excursions, to Cecil Hoffpauir for his hard work and expertise in working with the vibroseis trucks, to Dr. Farn- Yuh Menq and Dr. Brent Rosenblad for hands on training in many soil dynamics related issues, to Dr. Wen-Jong Chang for teaching me about his liquefaction vi research, to Frank Wise for his tutelage on electronics and circuitry, to Jeffery Lee, Asli Kurtulus and Yin-Cheng Lin for sharing an office and advice, to Wayne Fontenot, Max Trevino and Gonzalo Zapata for helping my to blow off steam and refine my ping-pong skills during lunch, and to Teresa Tice-Boggs, Chris Trevino and Alicia Zapata for their administrative support. I am most grateful to my dear wife, and eternal companion, Audrey. Her strength and support in my life cannot be quantified. She is such a wonderful mother to our two daughters, Kayla and Savannah. They have been understanding and extremely patient with me during the writing of this dissertation and my research related travels. I love them with all of my heart and cannot imagine a life without them. I also give thanks to my parents, Clayton and Jerri Lynn Cox. They set my feet on the path that has brought me to this point in my life. I am grateful for the principles they instilled in me as a young man and for their continued support, guidance and love for our family. I am also thankful for my parents-in-law, Curtis and Catherine Steele. In addition to their support and concern for us, their biannual trips to Austin have been especially enjoyable for Audrey, the girls and me. vii Development of a Direct Test Method for Dynamically Assessing the Liquefaction Resistance of Soils In Situ Publication No._____________ Brady Ray Cox, Ph.D. The University of Texas at Austin, 2006 Supervisor: Kenneth H. Stokoe, II This dissertation details work conducted by researchers from the University of Texas at Austin aimed toward the development and implementation of a new in-situ liquefaction testing technique. This technique is an active method that may be used to directly evaluate the liquefaction resistance of soils in place. The test is based on the premise of dynamically loading a native soil deposit in a manner similar to an earthquake while simultaneously measuring its response with embedded instrumentation. Dynamic loading is performed via a large, truck- mounted hydraulic shaker (vibroseis) that is used to excite the ground surface and generate stress waves of varying amplitudes within an instrumented portion of the soil mass. The embedded sensors consist of instrumentation to measure the coupled response of soil particle motion and pore water pressure generation. viii The validity of this new test method has been demonstrated by conducting field experiments at the Wildlife Liquefaction Array (WLA) in Imperial Valley, California. The extensive site characterization, the documented occurrence of earthquake-induced soil liquefaction at the site twice in the 1980’s, and the likelihood for re-liquefaction of the site during subsequent earthquakes make the WLA an ideal location for verifying the proposed in-situ dynamic liquefaction test method. In-situ liquefaction tests were carried out at three separate locations at the WLA. The tests were successful at measuring: (1) excess pore water pressure generation, and (2) nonlinear shear modulus behavior in the native silty-sand deposits as a function of induced cyclic shear strain and number of loading cycles. These results are compared to pore pressure generation curves and nonlinear shear modulus curves previously developed for WLA soils from laboratory testing methods. Variations in the dynamic soil response across the site are also discussed and the importance of evaluating liquefaction from direct in-situ measurements is emphasized. These accomplishments represent a large step forward in the ability to accurately evaluate the susceptibility of a soil deposit to earthquake-induced liquefaction. ix Table of Contents List of Figures xiv List of Tables xxxviii Chapter 1 1 Introduction 1 1.1 Earthquake-Induced Soil Liquefaction 1 1.2 Research Significance 2 1.3 Scope of Research 4 1.4 Organization of Dissertation 6 Chapter 2 11 Soil Liquefaction Background 11 2.1 Introduction 11 2.2 Liquefaction – A Complicated Phenomenon 11 2.3 Liquefaction Evaluation Procedures 20 2.4 In-Situ Soil Liquefaction Measurements 34 2.5 Need For A Dynamic In-Situ Liquefaction Test 37 2.6 Summary 38 Chapter 3 40 In-Situ Dynamic Liquefaction Test 40 3.1 Introduction 40 [...]... shear wave velocities from an in- situ liquefaction test with relatively large induced shear strains (γ ~ 0.045%) 144 Figure 6-21 Comparison between the amplitudes and phase of two separate receivers located at the same depth on either side of the base plate centerline during an in- situ dynamic liquefaction test 146 Figure 7-1 Map showing the location of the Wildlife Liquefaction Array (WLA) and the. .. array, the direction of dynamic excitation, the primary components of particle displacement, and the equation used to calculate the strain vector at the center of the element using a 4-node, finite element formulation 122 Figure 6-7 Example of a shear strain time history calculated at the center of the in- situ liquefaction sensor array using a 4-node, finite element strain formulation ... accelerometer during dynamic in- situ liquefaction testing; displayed in the: a) time domain, and b) frequency domain 110 Figure 6-3 Velocity signal obtained from integrating a single component of a 3D-MEMS accelerometer recorded during dynamic in- situ liquefaction testing; displayed in the: a) time domain, and b) frequency domain 113 Figure 6-4 Displacement signal obtained from double integration... during staged dynamic loading Series 2 at Test Location B, Wildlife Liquefaction Array 369 Figure 9-37 Comparison of the pore pressure generation curves obtained during Series 1 and Series 2 staged dynamic loading at Test Location B, Wildlife Liquefaction Array (WLA) 371 Figure 10-1 Approximate location of the in- situ liquefaction sensor array installed at Test Location A, Wildlife Liquefaction. .. 1999 Kocaeli, Turkey earthquake (Cox, 2001) 18 Figure 2-2 Liquefaction- induced bearing capacity failure of a 5-story building in Adapazari following the 1999 Kocaeli, Turkey earthquake (from www.eerc.berkeley.edu/turkey/adapazari) 19 Figure 2-3 Liquefaction- induced lateral spreading and settlement, coupled with tectonic subsidence, carried Hotel Sapanca partially into Lake Sapanca following the. .. integration of a single component of a 3D-MEMS accelerometer recorded during dynamic in- situ liquefaction testing; displayed in the: a) time domain, and b) frequency domain 114 xvii Figure 6-5 Representation of 4-node element in (a) the global coordinate system and (b) the natural coordinate system (from Chang, 2002) 117 Figure 6-6 Schematic detailing the liquefaction sensor array, the. .. 10-14 Force applied at the ground surface by T-Rex, shear strain induced at the center of the instrumented soil mass, and pore pressure ratios generated at each sensor location during Series 1, loading stage No 11; Test Location A, Wildlife Liquefaction Array 414 Figure 10-15 Force applied at the ground surface by T-Rex, shear strain induced at the center of the instrumented soil mass, and... 8-32 Force applied at the ground surface by T-Rex, shear strain induced at the center of the instrumented soil mass, and pore pressure ratios generated at each sensor location during Series 2, loading stage No 11; Test Location C, Wildlife Liquefaction Array 260 Figure 8-33 Force applied at the ground surface by T-Rex, shear strain induced at the center of the instrumented soil mass, and... the liquefaction sensor array (August 10-11, 2005) and from a separate set of crosshole tests (August 19, 2005) conducted approximately 6 ft south of the liquefaction sensor array at Test Location A, Wildlife Liquefaction Array (WLA) 401 xxxiii Figure 10-12 Force applied at the ground surface by T-Rex, shear strain induced at the center of the instrumented soil mass, and pore pressure ratios generated... shear strain induced at the center of the instrumented soil mass, and pore pressure ratios generated at each sensor location during Series 1, loading stage No 8; Test Location B, Wildlife Liquefaction Array 328 Figure 9-13 Force applied at the ground surface by T-Rex, shear strain induced at the center of the instrumented soil mass, and pore pressure ratios generated at each sensor location . make the WLA an ideal location for verifying the proposed in- situ dynamic liquefaction test method. In- situ liquefaction tests were carried out at three separate locations at the WLA. The tests. Youd Development of a Direct Test Method for Dynamically Assessing the Liquefaction Resistance of Soils In Situ by Brady Ray Cox, M.S. Dissertation Presented to the Faculty of the. side of the base plate centerline during an in- situ dynamic liquefaction test. 146 Figure 7-1 Map showing the location of the Wildlife Liquefaction Array (WLA) and the epicenters for the 1981