Rock Grouting

1 Introduction.- 2 Remarks on the Methodology of Preparation.- 3 Analysis of Completed Grouting Programmes.- 3.1 Preliminary Remarks.- 3.1.1 Selection of the Programmes; Data.- 3.1.2 Representation of Grouting Data.- 3.2 Description and Evaluation of the Programmes.- 3.2.1 Grouting Programmes in Folded Siltstone-Sandstone Alternations of the Westphalian Upper Carboniferous.- 3.2.1.1 The Grouting Programme at the Mohne Dam.- 3.2.1.2 The Aabach Dam Grouting Programme.- 3.2.2 Grouting Programmes in Buntsandstein.- 3.2.2.1 The Grouting Programme at the Haune Dam.- 3.2.2.2 The Antrift Dam Grouting Programme.- 3.2.2.3 The Twiste Dam Grouting Programme.- 3.2.2.4 Conclusions and Recommendations for Grouting Programmes in Buntsandstein and in Similar Rock Types.- 3.2.3 Grouting Programmes in Turonian Limestone of Southeastern Westphalia.- 3.2.3.1 Location, Geology, Hydraulic Routing.- 3.2.3.2 The Grouting Programme in Downtown Paderborn.- 3.2.3.3 The Grouting Programme for the Haxter Valley Bridge.- 3.2.4 The Tavera Dam Grouting Programme in Oligocene Conglomerate.- 3.3 Microscopical Studies.- 3.3.1 Purpose and Origin of Samples.- 3.3.2 Size of the Injectable Voids.- 3.3.3 The Process of Sedimentation, Separation and Drainage of the Excess Water.- 3.3.4 The Influence of the Grouting Pressure (Rock Fracturing).- 3.4 Generally Valid Conclusions from the Analysis of the Grouting Programmes.- 4 Discussion of the Conventional Investigation Methods for Determining Rock Permeability.- 4.1 Introduction.- 4.2 On the Execution, Evaluation and Interpretation of Water Pressure Tests.- 4.2.1 The Layout of the Tests.- 4.2.2 Testing Scheme.- 4.2.3 Several Aspects of the Practical Execution and Evaluation of Water Pressure Tests.- 4.2.3.1 The Pump.- 4.2.3.2 The Packer.- 4.2.3.3 Recording of Test Data.- 4.2.3.4 Evaluation of the Measured Data.- 4.3 Assessment of Current Investigation Methods for Rock Permeability.- 4.3.1 Water Pressure Tests and kf-Coefficient.- 4.3.2 On the Applicability of the Lugeon Criterion; Appropriate Impermeabilization Criteria.- 4.3.3 WPT Rates and the Appraisal of the Specific Rock Permeability.- 4.4 Conclusions.- 5 On Hydraulic Routing in Rock.- 5.1 Introduction.- 5.2 Methods of Researching the Hydraulic Routing in Rock.- 5.3 Influential Factors in the Development of Water Paths in Rock.- 5.4 Discontinuities as Prescribed Water Paths and Their Behaviour During Grouting.- 5.4.1 Preliminary Remarks.- 5.4.2 Bedding Planes.- 5.4.3 Joint Planes.- 5.4.4 Cleavage Planes.- 5.4.5 Faults.- 5.4.6 Dissolution Cavities.- 5.5 The Results of Field Investigations of the Hydraulic Routing.- 5.5.1 Hattelberg Tunnel.- 5.5.2 Oker-Grane Tunnel.- 5.5.3 Outcrops at the Aabach Dam Project.- 5 .5 .3 .1 Preliminary Remarks.- 5.5.3.2 Excavations at the Main Dam.- 5.5.3.3 Karbach Tunnel.- 5.5.3.4 Summary.- 5.5.4 Hydraulic Routing in the Buntsandstein.- 5.5.5 Hydraulic Routing of the Upper Turonian Limestone of Southeast Westphalia.- 5.5.6 Exploratory Addits for a Pump Storage Scheme in Taiwan.- 5.5.7 Outcrops at the Tavera Project.- 5.5.8 Other Indications Concerning Hydraulic Routing.- 5.6 Synopsis of the Percolation Behaviour in Rock.- 5.7 Remarks on Percolation Models and Calculation Methods in Rock Mechanics.- 6 Studies of the Relationship Between the Type of Hydraulic Routing, the Course of the Water Pressure Tests and Grouting Behaviour.- 6.1 Introduction.- 6.2 Tests Using Geologically Defined Models for the Hydraulic Routes Around the Boreholes.- 6.2.1 Prerequisites.- 6.2.2 Description of the Models, Arrangements of the Tests.- 6.2.3 Results of Simulated Water Pressure Tests.- 6.2.4 Results of Simulated Grouting Tests.- 6.3 Interpretation of Simulated Water Pressure Tests and Conclusions.- 6.3.1 Conclusions Concerning the Type of Hydraulic Routing: Direct or Indirect Communication.- 6.3.2 Conclusions Concerning the Size of the Routes in Relation to the Lugeon Criterion.- 6.3.3 Conclusions Concerning the Type of Water Paths Drawn from the Absorption Rates.- 6.3.4 Possibilities for Misinterpreting Water Pressure Tests.- 6.4 Interpretation of Simulated Grouting Tests and Conclusions.- 6.4.1 Required Pressures for Grouting Very Fine Routes, Rock-Type-Specific Groutability.- 6.4.2 The Parallel Grouting of Dissimilar Water Paths.- 6.4.3 Interplay Between Extension and Velocity of Grout Travel, Causes for Buildup of Pressure, Groutability and Grout Takes Dependent upon the Type of the Conductivity, Remaining Permeability.- 7 Practical Field Investigations on Permeability by Means of Water Pressure Tests.- 7.1 Introduction.- 7.2 Rock Fracturing Contingent upon Injection Pressure.- 7.3 Appropriate Maximum Pressures for Water Pressure Tests.- 7.4 The Factor "Time" in Conducting the Water Pressure Tests.- 7.5 Characteristic Water Pressure Tests for Determining the Permeability Behaviour of Different Rock Types.- 7.5.1 Classification of the Water Pressure Tests, "Basic Types".- 7.5.2 Geological Conditions for the Basic Types of Water Pressure Tests.- 7.5.3 Discussion of Actual Test Diagrams.- 7.5.3.1 Water Pre.ssure Tests in Impermeable Rock (Group 1).- 7.5.3.2 Water Pressure Tests in Rock of Unchangeable Permeability (Group 2).- 7.5.3.3 Water Pressure Tests in Rock of Changeable Permeability (Group 3).- 7.5.3.4 Water Pressure Tests in Rock of Very Changeable Permeability (Group 4).- 7.5.3.5 Time-Dependent Fracturing Processes (P-Q-t-Diagrams).- 7.5.3.6 Conclusions: Catalogue of the Possible Rock Permeabilities Based on the Water Pressure Tests.- 7.6 Comparison of Rock Permeabilities Under the Conditions of Injection and Operation.- 7.7 Water Pressure Tests in Grouted Rocks for Controlling its Success.- 7.8 On the Definition of "Reference" Pressure.- 8 Practical Criteria for Determining Grouting Methods Considering Rock-Type-Specific Groutability.- 8.1 Introduction.- 8.2 Selection of Grouting Pressures in View of the Fracturing Behaviour.- 8.3 Assessing the Rock-Type-Specific Groutability.- 8.3.1 Orientation and Types of Separation Planes Related to the Specific Conditions for Grouting.- 8.3.2 Relationships Between WPT Rates and Grout Takes.- 8.3.3 The "Specific Absorption Rate" as an Indicator for Groutability.- 8.3.4 Mapping Separation Planes from Drill Cores and Their Representation.- 8.3.5 Conclusions Concerning Groutable Permeability and Grouting Pressure.- 8.4 Penetration or Displacement Grouting?.- 8.5 Comments on Setting W/C Ratios.- 8.6 Spacing of Grout Holes, Grouting in Series.- 8.7 Downstage or Upstage Grouting, Schematic or Adapted Execution, Accompanying Water Pressure Tests.- 8.8 Relationship Between the Type of Hydraulic Routing and the Remaining Permeability.- 8.9 Test Grouting.- 9 Practical Criteria for Determining the Tolerable Permeability.- 9.1 Introduction, Hydraulic Fundamentals, Depth of the Curtain, "Tolerable Permeability".- 9.2 Estimating the Mean Permeability of the Rock for Determining Seepage Losses.- 9.2.1 Problem and Possible Solutions.- 9.2.2 Determining kf by a "Modified Well Method".- 9.2.3 Determining kf on the Basis of a Coefficient of Infiltration.- 9.2.4 Estimating kf on the Basis of the Inclination of the Groundwater Table.- 9.3 Erodibility.- 9.4 Examples of the Possible Differences Between Groutable and Tolerable Permeabilities.- 9.5 Changes in Permeability and Groutability Due to Comparatively High Storage Levels.- 9.6 The Expenditures for Grouting Programmes Compared with the Degree of Impermeabilization.- 9.7 Summarizing Assessment of the Tolerable Permeability.- 9.8 The Expediency of a Control Gallery Considering Geological Setting and Rock-Type-Specific Groutability.- 9.9 Lateral Extension of the Grout Curtain, Systematic Groundwater Measurements Prior to the Construction of the Dam.- 9.10 Influence of the Type of the Project on the Tolerable Permeability.- 10 The Influence of the Local Geological Setting and the Grouting Measures on the Reduction of Uplift.- 10.1 Introduction.- 10.2 Example: Aabach Dam.- 10.3 Example: Antrift Dam.- 10.4 Example: Tavera Dam.- 10.5 Example: Twiste Dam.- 10.6 Conclusions Concerning the Reduction of the Uplift.- 11 Final Remarks: an Attempt at Guide-Lines.- 11.1 Hydrogeological Scope.- 11.2 Site Investigations by Geological Mapping, Core Drilling, Testing of Both Permeability and Groutability.- 11.3 Control Measures During Impoundment.