The Deep Mixing Method

Transcription

1 The Deep Mixing Method Masaki Kitazume Tokyo Institute oftechnology.tokyo, Japan Masaaki Terashi Consultant, Tokyo, japan Taylor & Francis Group Boca Raton London New York Leiden CRC Press is an imprint of the Taylor & Francis Croup, an informa business A BALKEMA BOOK

2 evolution historical Preface List of technical terms and symbols xvii xix I Overview of ground improvement and scope of the book of deep mixing I 1 Introduction 1 2 Classification of ground improvement technologies Replacement Densification Consolidation/dewatering Grouting Admixture stabilization Thermal stabilization (heating and freezing) Reinforcement Combined uses of various techniques Limitation of traditional ground improvement techniques 8 3 Development of deep mixing in Japan review Development of the deep mixing method Development of high pressure injection deep mixing method 12 4 Diversified admixture stabilization techniques without compaction Classification of admixture stabilization techniques Insitu mixing Surface treatment Shallow mixing Deep mixing method Exsitu mixing Premixing method Lightweight Geomaterial Dewatered stabilized soil Pneumatic flow mixing method 23 5 Scope of the text 24 References 26

3 vi 2 Factors affecting strength increase 29 1 Introduction 2 Influence of various factors on strength of lime stabilized soil Mechanism of lime stabilization 2.2 Characteristics of lime as a binder Influence of quality of quicklime 2.3 Characteristics and conditions of soil Influence of soil type Influence of grain size distribution Influence of humic acid Influence of potential Hydrogen (ph) Influence of water content 2.4 Mixing conditions Influence of amount of binder Influence of mixing time 2.5 Curing conditions Influence of curing period 39 3 Influence of various factors on strength of cement stabilized soil Mechanism of cement stabilization Characteristics of binder Influence of chemical composition of binder Influence of type of binder Influence of type of water Characteristics and conditions of soil Influence of soil type Influence of grain size distribution Influence of humic acid Influence of ignition loss Influence of ph Influence of water content Mixing conditions Influence of amount of binder Influence of mixing time Influence of time and duration of mixing and holding process Curing conditions Influence of 59 curing period Influence of curing temperature Influence of maturity Influence of overburden pressure 67 4 Prediction of strength 68 References 69 3 Engineering properties of stabilized soils Introduction 2 Physical properties 2.1 Change of water content

4 consolidation vii 2.2 Change of unit weight Change of consistency of soilbinder mixture before hardening 78 3 Mechanical properties (strength characteristics) Stressstrain curve Strain at failure Modulus of elasticity (Yong's modulus) Residual strength Poisson's ratio Angle of internal friction Undrained shear strength Dynamic property Creep strength Cyclic strength Tensile and bending strengths Long term strength Strength increase Strength decrease Strength distribution Calcium distribution in specimens Depth of deterioration Mechanical properties (consolidation characteristics) Void ratio pressure curve Consolidation yield pressure Coefficient of consolidation and coefficient of volume compressibility Coefficient of permeability Permeability of stabilized clay Influence of grain size distribution on the coefficient of permeability of stabilized soil Environmental properties Elution of contaminant Elution of Hexavalent chromium (chromium VI) from stabilized soil Resolution of alkali from stabilized soil Engineering properties of cement stabilized soil manufactured in situ Mixing degree of insitu stabilized soils Water content distribution Unit weight distribution Variability of field strength Difference in strength of field produced stabilized soil and laboratory prepared stabilized soil Size effect on unconfined compressive strength Strength and calcium distributions at overlapped portion Test conditions Calcium distribution Strength distribution Effect of time interval 133

5 consolidation viii 7 Summary 7.1 Physical properties Change of water content and density Change of consistency of soilbinder mixture before hardening Mechanical properties (strength characteristics) Stressstrain behavior Poisson's ratio Angle of internal friction Undrained shear strength Dynamic property Creep and cyclic strengths Tensile and bending strengths Long term strength Mechanical properties (consolidation characteristics) Void ratio pressure curve Coefficient of consolidation and coefficient of volume compressibility Coefficient of permeability Environmental 137 properties Elution of contaminant Resolution of alkali from a stabilized soil Engineering properties of cement stabilized soil manufactured in situ Water content and unit weight by stabilization Variability of field strength Difference in the strength of field produced stabilized soil and laboratory prepared stabilized soil Size effect on unconfined compressive strength Strength distributions at overlapped portion 138 References Applications Introduction Patterns of applications 2.1 Size and geometry of the stabilized soil element Column installation patterns by the mechanical deep mixing method Group column type improvement Wall type improvement Grid type improvement Block type improvement Column installation pattern by high pressure injection Improvement purposes and applications Mechanical deep mixing method High pressure injection 153

6 for ix 4 Applications in Japan Statistics of applications Mechanical deep mixing Statistics of high pressure injection Selected case histories Group column type individual columns for settlement reduction Introduction and ground condition Ground improvement Group column type tangent block embankment stability Introduction and ground condition Ground improvement Grid type improvement for liquefaction prevention Introduction and ground condition Ground improvement Block type improvement to increase bearing capacity of a bridge foundation Introduction and ground condition Ground improvement Block type improvement for liquefaction mitigation Introduction and ground condition Ground improvement Grid type improvement for liquefaction prevention Introduction and ground condition Ground improvement Block type improvement for the stability of a revetment Introduction and ground condition Ground improvement Jet grouting application to shield tunnel Introduction and ground condition Ground improvement Performance of improved ground in the 2011 Tohoku earthquake Introduction Improved ground by the wet method of deep mixing Outline of survey Performance of improved ground River embankment in Saitama Prefecture River embankment in Ibaraki Prefecture Road embankment in Chiba Prefecture Improved ground by the dry method of deep mixing Outline of survey Performance of improved ground River embankment in Chiba Prefecture Road embankment in Chiba Prefecture Box culvert in Chiba Prefecture 182

7 x 5.4 Improved ground by Grouting method Outline of survey Performance of improved ground River embankment at Tokyo Approach road to immerse tunnel in Kanagawa Prefecture Summary 184 References Execution equipment, procedures and control Introduction Deep mixing methods by mechanical mixing process Deep mixing methods by high pressure injection mixing process Classification of deep mixing techniques in Japan Dry method of deep mixing for onland works Dry jet mixing method Equipment System and specifications Mixing tool Binder plant Control unit Construction procedure Preparation of site Field trial test Construction work Quality control during production Quality assurance Wet method of deep mixing for onland works Ordinary cement deep mixing method Equipment System and specifications Mixing tool Binder plant Control unit Construction procedure Preparation of site Field trial test Construction work Quality control during production Quality assurance CDMLODIC method Equipment System and specifications Mixing tool Binder plant Control unit 213

8 horizontal xi Construction procedure Preparation of site Field trial test Construction work Quality control during production Quality assurance Effect of method displacement during execution CDMLemni 2/3 method Equipment System and specifications Mixing tool Binder plant Control unit Construction procedure Preparation of site Field trial test Construction work Quality control during execution Quality assurance Effect of method Wet method of deep mixing for inwater works Cement deep mixing method Equipment System and specifications Mixing tool Plant and pumping unit Control room Construction procedure Site exploration and examination of execution circumstances Positioning Field trial test Construction work Quality control during production Quality assurance Additional issues to be considered in the mechanical mixing method Soil improvement method for locally hard ground Noise and vibration during operation Lateral displacement and heave of ground by deep mixing work Onland work Inwater work High pressure injection method Single fluid technique (CCP method) Equipment Construction procedure 237

9 xii Preparation of site Construction work Quality control during production Quality assurance Double fluid technique (JSG method) Equipment Construction procedure Preparation of site Construction work Quality control during production Quality assurance Double fluid technique (Superjet method) Equipment Construction procedure 244 of site Preparation Construction work Quality control during production Quality assurance Triple fluid technique (CJG method) Equipment Construction procedure 248 of site Preparation Construction work Quality control during production Quality assurance Triple fluid technique (Xjet method) Equipment Construction procedure Preparation of site Construction work Quality control during production Quality assurance Combined technique JACSMAN method Equipment System and specifications Mixing shafts and mixing blades Plant and pumping unit Control unit Construction procedure Preparation of site Field trial test Construction work Quality control during production Quality assurance Effect of method 260 References 261

10 selection xiii 6 Design of improved ground by the deep mixing method Introduction Engineering behavior of deep mixed ground Various column installation patterns and their applications Engineering behavior of block (grid and wall) produced by overlap operation Engineering behavior of improved ground leading to external instability Engineering behavior of improved ground leading to internal instability Change of failure mode Influence of strength ratio qublqus on vertical bearing capacity Influence of load inclination Influence of overlap joint on mode of failure Influence of overlap joint on external stability Influence of overlap joint on internal stability Summary of failure modes for block type improvement Engineering behavior of a group of individual columns Stability of a group of individual columns Bearing capacity of a group of individual columns Embankment stability on a group of individual columns Numerical simulation of stability of embankment Summary of failure modes for a group of stabilized soil columns Work flow of deep mixing and design Work flow of deep mixing and geotechnical design Work flow of deep mixing Strategy of column installation pattern Design procedure for embankment support, group column type improved ground Introduction Basic concept Design procedure Design flow Trial values for dimensions of improved ground Examination of sliding failure Slip circle analysis Examination of horizontal displacement Examination of bearing capacity Examination of settlement Amount of settlement for fixed type improved ground 303

11 xiv Amount of settlement for floating type improved ground Rate of settlement Important issues on design procedure Strength of stabilized soil column, improvement area ratio and width of improved ground Limitation of design procedure based on slip circle analysis Design procedure for block type and wall type improved grounds Introduction Basic concept Design procedure Design flow Examination of the external stability of a superstructure Trial values for the strength of stabilized soil and geometric conditions of improved ground Examination of the external stability of improved ground Sliding and overturning failures Bearing capacity Examination of the internal stability of improved ground Subgrade reaction at the front edge of improved ground Average shear stress along a vertical plane Allowable strengths of stabilized soil Extrusion failure Slip circle analysis Examination of immediate and long term settlements Determination of strength and specifications of stabilized soil Sample calculation Important issues on design procedure Design procedure for block type and wall type improved grounds, reliability design Introduction Basic concept Design procedure Design flow Examination of external stability of a superstructure Sliding failure Overturning failure Setting of geometric conditions of improved ground Evaluation of seismic coefficient for verification For level 1 performance verification For level 2 performance verification Examination of the external stability of improved ground Sliding failure Overturning failure Bearing capacity Examination of internal stability of improved ground 344

12 current xv Subgrade reactions at front edge of improved ground Average shear stress along a vertical shear plane Allowable strengths of stabilized soil Extrusion failure Slip circle analysis Examination of immediate and long term settlements Determination of strength and specifications of stabilized soil Design procedure of grid type improved ground for liquefaction prevention Introduction Basic concept Design procedure Design flow Design seismic coefficient Determination of width of grid Assumption of specifications of improved ground Examination of the external stability of improved ground Sliding and overturning failures Bearing capacity Examination of the internal stability of improved ground Subgrade reaction at the front edge of improved ground Average shear stress along a horizontal shear plane Average shear stress along the horizontal plane of the rear most grid wall Average shear stress along a vertical shear plane Slip circle analysis Important issues on design procedure Effect of grid wall spacing on liquefaction prevention 364 References QC/QA for improved ground Current practice and future research needs Introduction Flow of a deep mixing project and QC/QA QC/QA for stabilized soil practice Relation of laboratory strength, field strength and design strength Flow of quality control and quality assurance Laboratory mix test 374

13 research xvi Field trial test Quality control during production Quality verification Technical issues on the QC/QA of stabilized soil Technical issues with the laboratory mix test Effect of rest time Effect of molding Effect of curing temperature Impact of diversified execution system on QC/QA Verification techniques QC/QA of improved ground needs Embankment support by group of individual columns QC/QA associated with current design practice QC/QA for sophisticated design procedure considering the actual failure modes of group column type improved ground Practitioners'approach Block type and wall type improvements for heavy structures Summary 391 References 392 Appendix A Japanese laboratory mix test procedure Introduction Testing equipment Equipment for making specimen Mold Mixer Binder mixing tool Soil and binder Soil Binder Making and curing of specimens Mixing materials Making specimen Curing Specimen removal Report Use of specimens 405 References 405 Subject index 407