electro-osmotic grouting technique for liquefaction-mitigation of low permeability silty soils

ELECTRO-OSMOTIC GROUTING TECHNIQUE FOR LIQUEFACTION-MITIGATION OF LOW PERMEABILITY SILTY SOILS by WEIWEI JIA September 2006 A dissertation submitted to the Faculty of the Graduate School of the State University of New York at Buffalo in partial fulfillment of the requirements for the degree of Doctor of Philosophy Department of Civil, Structural and Environmental Engineering UMI Number: 3226603 3226603 2006 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 by ProQuest Information and Learning Company. ABSTRACT Electro-osmotic grouting is a new foundation improvement technique proposed to treat low permeability, liquefiable silty soils underneath existing structures for the purpose of liquefaction-mitigation. This technique uses a d.c. current to introduce water soluble grout materials and reactants into the silty soils. Setting time of injected grouts can be controlled by adjusting the concentration and sequence of introduction of various components. Both experimental and numerical studies were performed in this research. Experiments were conducted to prove the feasibility of electro-osmotic injection under 1- D and 3-D conditions, to quantify the increase of liquefaction resistance in silty soils due to electro-osmotic grouting, and to design grout mixes feasible for electro-osmotic grouting. Numerical analyses were performed to simulate grout flows under a 3-D condition, to determine the rate and extent of grout penetration, and to estimate power consumption in electro-osmotic grouting. Study shows that electro-osmotic grouting is a promising technique. Colloidal silica and sodium silicate grouts can be injected into low permeability sility soils at the rate of about cm/s per v/cm, and liquefaction resistance of the silty soils increased signicantly after injection. 5 10 − Thesis Advisor: Professor Sabanayagam Thevanayagam ii ACKNOWLEDGEMENTS I wish to express my deepest appreciation to my academic advisor – Dr. Sabanayagam Thevanayagam, for his invaluable guidance, suggestions, as well as support and continuous encouragement, without which this work would not be possible. Conducting this research work under his guidance was a rewarding experience. I believe I will always benefit from it in my future work and study. My sincerely appreciation also goes to Professor Shahid Ahmad and Professor Amjad Aref for their encouragement and support throughout the study. I would like to say thanks to graduate students T. Shenthan and T. Kanagalingam, who helped a lot in carrying out cyclic and monotonic triaxial tests, and provided valuable suggestions and recommendations in the completion of the dissertation. Shenthan also reviewed the whole dissertation and provided valuable comments. My deepest gratitude also goes to my parents and my aunt, for their assistance and encouragement for the successful completion of this study. Funding for this research work is provided by MCEER Hospital Project. The financial support is greatly appreciated. Finally, I dedicate this work to my wife, Huifen Zhu. iii TABLE OF CONTENTS CONTENTS PAGE ABSTRACT ii ACKNOWLEDGMENT iii TABLE OF CONTENTS iv LIST OF TABLES ix LIST OF FIGURES xi NOTATIONS xv I. INTRODUCTION 1 1.1 Background 1 1.2 Scope of Study 3 1.3 Organization 4 II. LITERATURE REVIEW 6 2.1 Liquefaction Related Phenomena 6 2.1.1 Introduction 6 2.1.2 Liquefaction 6 2.1.3 Ground Failure Associated with Liquefaction 11 2.2 Current Soil Improvement Techniques For Liquefaction Remediation 15 2.3 Traditional Grouting Techniques 18 2.3.1 Grouting 18 2.3.2 Permeation Grouting 21 2.3.2.1 Materials for Permeation Grouting 23 2.3.2.1.1 Materials for Suspensions 23 2.3.2.1.2 Chemical Grouting and Chemical Grouts 24 2.3.2.2 Sodium Silicate Based Grouts 26 2.3.2.3 Groutability 29 2.3.2.4 Cost of Permeation Grouting 30 2.3.2.5 Case Histories of Liquefaction-mitigation with Permeation Grouting 31 2.4 Electro-Kinetic Phenomena And Their Applications 31 2.4.1 Electro-kinetic Phenomena 31 2.4.1.1 Electro-Osmosis 31 2.4.1.2 Electro-Phoresis 33 2.4.1.3 Streaming Potential 34 iv 2.4.1.4 Electro-Migration 34 2.4.2 Boundary Conditions of Electro-Osmotic Flow 35 2.4.3 Application of Electro-Kinetic Phenomena 37 2.4.3.1 Electro-Kinetic Remediation of Fine-Grained Contaminated Sites 38 2.4.3.2 Injection of Ions and Nutrients 39 2.4.3.3 Electro-Kinetic Barriers 39 2.4.3.4 Stabilization of Excavations or Fine-Grained Soils 40 2.4.3.5 Dewater and Consolidation of Fine Grained Soils, Waste Sludge, and Minerals 41 III. ELECTRO-OSMOTIC GROUTING 43 3.1 Introduction 43 3.2 Electrolysis Reactions 45 3.3 General Species Conduction Theory Under Electric Field 47 3.3.1 Diffusion 48 3.3.2 Electro-Osmosis 48 3.3.3 Electro-Migration 49 3.3.4 Hydraulic Flow 50 3.3.5 Species Conduction Under One- Dimensional Coupled Field 50 3.4 Species Conduction in Electro-osmotic Injection 51 3.5 Factors Affecting Electro-Osmotic Injection 55 3.5.1 Change of Soil Properties During Electro-Osmotic Injection 56 3.5.2 Factors Affecting Power Consumption in Electro-Osmotic Grouting 57 3.6 Proposed Strategies for Field Implementation 58 3.6.1 Vertical Layout and its Application – Single-Borehole Layout 59 3.6.2 Vertical Layout and its Application – Multiple-Borehole Layout 60 3.6.3 Horizontal Layout and its Application 60 IV. GROUT MIX DESIGN 65 4.1 Introduction 65 4.2 Grout Materials 66 4.2.1 Sodium Silicate 66 4.2.2 Colloidal Silica – Nyacol 215 and LUDOX SM-30 69 4.2.3 Acrylamide Grout 71 4.3 Gelling Time Tests on LUDOX SM-30 73 4.3.1 Test Procedure 73 4.3.2 Observations 74 4.3.3 Results 75 4.4 Conclusions and Comments 77 v V. 1-D FEASIBILITY STUDY ON ELECTRO-OSMOTIC INJECTION 79 5.1 Introduction 79 5.2 Materials and Experimental Setup 79 5.2.1 Soil 79 5.2.2 Grout Materials 80 5.2.3 Electrode Material 80 5.2.4 Experimental Setup 81 5.3 Experiments 82 5.3.1 Experimental Procedure 84 5.3.2 Measurements 85 5.4 Results 86 5.4.1 Injection of Sodium Silicate 86 5.4.2 Injection of Colloidal Silica 89 5.4.3 Injection of with AV-100 91 5.5 Conclusions 94 VI. UNDRAINED BEHAVIOR AND LIQUEFACTION POTENTIAL OF GROUTED SOIL 95 6.1 Introduction 95 6.2 Materials 95 6.2.1 Soil 95 6.2.2 Grout Materials 95 6.3 Electro-Osmotic Injection 96 6.3.1 Experimental Setup 97 6.3.1.1 Specimen Mold 97 6.3.1.2 Electro-osmotic Cell 98 6.3.1.3 Experimental Setup 99 6.3.2 Test Procedure 100 6.4 Undrained Triaxial Test 102 6.4.1 Experimental Setup 102 6.4.2 Test Procedure 104 6.5 Sodium Silicate (Grade N ® )Treated Specimens 106 6.5.1 Undrained Cyclic Strength 106 6.5.1.1 Experiments 106 6.5.1.2 Results 107 6.5.2 Undrained Monotonic Strength 108 6.5.2.1 Experiments 108 6.5.2.2 Results 109 6.6 Colloidal Silica (LUDOX SM-30) Treated Specimens 112 6.6.1 Undrained Cyclic Strength 112 6.6.1.1 Experiments 112 6.6.1.2 Results 113 6.6.2 Undrained Monotonic Strength 114 6.6.2.1 Experiments 114 vi 6.6.2.2 Results 115 6.7 Application of Lab Test Result in Practical Design 116 6.7.1 Introduction 116 6.7.2 Proposed Relationship for versus - Ungrouted Soils 117 CS N 601 )( L E 6.7.3 Proposed Relationship for versus - Grouted Soils 121 CS N 601 )( L E 6.7.4 Practical Application of Correlation Chart 124 6.8 Conclusion 125 VII. THEORETICAL STUDY ON THE GROUT FLOW IN 3-D ELECTRO-OSMOTIC INJECTION 126 7.1 Introduction 126 7.2 Flow Field Analogy 129 7.2.1 Hydraulic Flow 131 7.2.2 Electric Flow 133 7.2.3 Electro-osmotic Flow 135 7.2.4 Concept of Analogy 135 7.2.5 Equivalent Flow Field Equations 137 7.3 Guidelines for Simulation of Electro-osmotic Grouting 139 7.4 Application of the Analogy 141 7.4.1 MODFLOW 132 7.4.2 The Electric Field and Electro-osmotic Flow Field 142 7.4.3 Hydraulic Flow Model 142 7.4.4 Numerical Solution 144 7.5 Cost of Electro-Osmotic Injection 145 7.5.1 Theoretical Analysis On Unit Power Consumption 145 7.5.2 Parametric Study on Unit power consumption 147 7.6 Conclusion 147 VIII. 3-D FEASIBILITY TEST OF ELECTRO-OSMOTIC INJECTION 152 8.1 Introduction 152 8.2 Experimental Program 153 8.2.1 Materials 153 8.2.1.1 Soils 153 8.2.1.2 Grout Material 153 8.2.2 Experimental Setup 154 8.2.3 Test Procedure 155 8.2.4 Control Test 155 8.3 Test Result 156 8.4 Theoretical Study of the 3-D Bench Scale Test 159 8.4.1 Numerical Model of the Electro-Osmotic and Electric Current Flow 160 8.4.2 The Hydraulic Flow Model 160 8.4.3 Numerical Solution to The Hydraulic Flow Problem 161 vii 8.4.4 Analysis 161 8.5 Conclusion 162 IX. FEASIBILITY STUDY OF FIELD APPLICATION OF ELECTRO-OSMOTIC GROUTING – AN EXAMPLE 164 9.1 Introduction 164 9.2 Sample Site 165 9.2.1 Liquefaction Potential at the Site 167 9.2.2 Rationale for Selection of Electro-Osmotic Grouting for Liquefaction-mitigation 170 9.3 Post-Treatment Cyclic Resistance 171 9.4 Post Treatment Bearing Capacity 172 9.4.1 Foundation Design Loads 172 9.4.2 Post-Treatment Soil Compression Strength 174 9.4.3 Design Requirement of Grouted Zone 175 9.5 Implementation Of Electro-Osmotic Grouting 176 9.5.1 Construction Procedure 176 9.5.2 Grouting Pipes 179 9.5.3 Power Voltage Selection 179 9.5.4 Equipment 179 9.5.5 Sequence of Injection 180 9.5.6 Grout Mix Setting Time 182 9.5.7 Cost of Implementation 182 9.6 Estimate Of Grouting Duration And Grout Penetration 184 9.6.1 Hydraulic Flow Model 184 9.6.2 Penetration and Injection Duration 184 9.7 Quality Control Of Electro-Osmotic Grouting 187 9.8 Conclusion 187 X. CONCLUSIONS 189 XI. RECOMMENDATIONS FOR FUTURE RESEARCH 192 REFERENCES 194 APPENDIX A TEST SUMMARY OF THE 1-D ELECTRO- OSMOTIC INJECTION FEASIBILITY STUDY 205 APPENDIX B: TEST SUMMARY OF THE STUDY ON UNDRAINED BEHAVIOR AND LIQUEFACTION POTENTIAL OF GROUTED SOIL 210 APPENDIX C: TEST SUMMARY OF THE 3-D ELECTRO- OSMOTIC INJECTION FEASIBILITY STUDY 224 viii LIST OF TABLES Table 1.1 Conventional Liquefaction-mitigation Techniques 2 Table 2.1 Cost Estimates for Current Grouting Techniques 21 Table 2.2 Limits of Penetration of Cement into Granular Soils 29 Table 2.3 Relationships Between the Viscosities of 29 Table 3.1 Standard Reduction Potentials at 25 o C 45 Table 3.2 Advantages and Disadvantages of Proposed Strategies 61 Table 4.1 Commonly Used Chemical Grouts 65 Table 4.2 Grout Materials Used in the Study 66 Table 4.3 Specifications of N ® Sodium Silicate 68 Table 4.4 Specifications of Calcium Chloride 68 Table 4.5 Specifications of Nyacol ® 215 Colloidal Silica 70 Table 4.6 Specifications of LUDOX SM-30 Colloidal Silica 70 Table4.7 Specifications of AV-100 72 Table 4.8 Jar-Test Gel State Codes (Sydansk 1990) 75 Table 4.9 Gel Test on Colloidal Silica – LUDOX SM-30 76 Table 5.1 Grout Injection Feasibility Test 82 Table 5.2 Soil pH, Conductivity, and Strength 83 Table 6.1 The Size, Electric Gradients, and Durations of Injection of Two Kinds of Specimens 100 Table 6.2 Undrained Cyclic Triaxial Tests on N ® Sodium Silicate Treated Specimens 107 Table 6.3 Test Parameters for Undrained Cyclic Triaxial Tests on ix [...]... when silt content of soil is higher than 10 to 15%, even permeation grouting is ineffective The low permeability of silty soils makes it impractical, if not impossible, to effectively inject the grouts by permeation New technology needs to be developed to treat the liquefiable low permeability silty soils underneath existing structures Table 1.1 Conventional Liquefaction-mitigation Techniques (From... the feasibility of field application of this new technique Laboratory tests involved the development of test devices and procedure for electro-osmotic injection, the design of test methods to evaluate the feasibility of electro-osmotic injection under 1-D and 3-D conditions, and the development of test devices and procedure to evaluate the increase of 3 liquefaction resistance in silty soils due to electric-osmotic... sequence of introduction of various components, and by careful selection of grouting material and reactants, the hardening time of the introduced grout mix can be controlled 1.2 SCOPE OF STUDY This dissertation presents the results of experimental and numerical studies performed to evaluate the feasibility of electro-osmotic injection, to study the level of improvement that could be achieved by electro-osmotic. .. selected grouts can be injected into low permeability sility soils at a reasonable rate, and liquefaction resistance of the silty soils increased signicantly after injection 1.3 ORGANIZATION Chapter 2 of this dissertation presents a brief historical review of liquefaction phenomena and traditional ground improvement techniques for liquefaction-mitigation A brief introduction of electro-kinetic phenomena is... relatively high speeds of tens 12 of km/h The movement will not stop until the driving forces are reduced to values less than the viscous shear resistance of the flowing material The moving soil may be composed of completed liquefied mass, or of intact material block floating in liquefied material Figure 2.7 Diagram of a Flow Failure Caused by Liquefaction and Loss of Strength of Soils Lying on a Steep... Figure 7.1 Field Application Strategy 1- Vertical Grouting 128 Figure 7.2 Simplified flow problem 128 Figure 7.3 Example Configuration of Electro-osmotic Grouting 140 Figure 7.4 Hydraulic Model for Simulation of Electric Field in Figure 7.3 140 Figure 7.5 Numerical Simulation of an Electro-Osmotic Injection Problem 141 Figure 7.6 Flow lines and extent of penetration 144 Figure 7.7 Unit power consumption... bench scale test and to analyze the test results To demonstrate the applicaton of this new technique, a sample design of electro-osmotic grouting for liquefaction-mitigation of silty soils underneath a hypothetical two-story hospital building is presented in Chapter 9 Conclusions based on the current study and recommendations for future study are presented in Chapters 10 and 11, respectively 5 Chapter... Schematic Diagram of Flow Barrier for Chemical Contaminant Using Electro-Osmosis 41 Figure 3.1 Schematic Diagram of Electro-Osmotic Injection 43 xi Figure 3.2 Electro-Kinetics under Electro-Osmotic Injection 51 Figure3.3 Transport of Silicate in Electro-Osmotic Injection 54 Figure 3.4 Electro-Osmotic Injection 62 Figure 3.5 Strategies of Field Application 63 Figure 4.1 Equipments for Setting time Test... chapter Chapter 3 focuses on the new electro-osmotic grouting technique Electrolysis reactions and species conduction during electro-kinetic processing of soils, species conduction during electroosmotic injection, and factors affecting the implementation of the electro-osmotic injection are discussed in this chapter Proposed strategies for field implementation of the technique are also provided in this... designed for electro-osmotic grouting is also discussed in this chapter Chapter 5 describes the experimental program to study the feasibility of 1-D electro-osmotic injection, including the electro-osmotic injection device, test procedure, and measurements and observations performed in the study A group of 1-D electro-osmotic injection tests were conducted and presented in 4 this chapter A total of three . ELECTRO-OSMOTIC GROUTING TECHNIQUE FOR LIQUEFACTION-MITIGATION OF LOW PERMEABILITY SILTY SOILS by WEIWEI JIA September 2006 . the increase of liquefaction resistance in silty soils due to electro-osmotic grouting, and to design grout mixes feasible for electro-osmotic grouting. Numerical analyses were performed to simulate. Guidelines for Simulation of Electro-osmotic Grouting 139 7.4 Application of the Analogy 141 7.4.1 MODFLOW 132 7.4.2 The Electric Field and Electro-osmotic Flow Field 142 7.4.3 Hydraulic Flow Model