FIELD INSTRUMENTATION FOR SOIL AND ROCK
CONTENTS 1 INTRODUCTION 1 1 1 HISTORY OF OBSERVATIONAL METHOD 2 1 2 TYPES OF GEOTECHNICAL INSTRUMENT 2 1 3 PLANNING GEOTECHNICAL INSTRUMENTATION PROJECT 3 1 4 GEOTECHNICAL INSTRUMENT INSTALLATION 5 1 5 MONITORING DATA PROCESSING DATA VERI CATION AND PRESENTATION 6 1 6 ANALYSES AND PERFORMANCE ASSESSMENT 6 1 7 FACTORS AFFECTING MEASURED INSTRUMENT DATA 7 1 8 CASE STUDIES 8 2 OBSERVATIONAL METHODS AND GEOTECHNICAL ISSUES 9 2 1 SETTLEMENT AND CONSOLIDATION 12 2 2 SLOPE INSTABILITY AND LATERAL DISPLACEMENT 17 2 3 GROUNDWATER AND POREWATER PRESSURES 23 2 4 VIBRATION MONITORING 26 2 5 STRUCTURAL DEFORMATION 28 2 5 1 STRESSES ON THE EARTH AND STRUCTURES 28 2 6 ADVANTAGE OF USING AND IMPLEMENTING GEOTECHNICAL INSTRUMENTATION PROGRAMME 28 3 TYPES OF INSTRUMENTS 31 3 1 DEFORMATION AND STRAIN MEASUREMENTS 31 3 1 1 SETTLEMENT PLATE 31 3 1 2 SETTLEMENT MARKER AND SETTLEMENT POINT 32 3 1 3 LIQUID SETTLEMENT GAUGE 32 3 1 4 DEEP SETTLEMENT GAUGE 33 3 1 5 MULTI LEVEL SETTLEMENT GAUGE 36 3 1 6 SETTLEMENT PRO LER 38 3 1 7 DEEP REFERENCE POINT 39 3 2 WATER LEVEL AND PRESSURE MEASUREMENTS 40 3 2 1 WATER STANDPIPE 40 3 2 2 CASAGRANDE OPEN TYPE PIEZOMETER 41 3 2 3 CLOSED TYPE PIEZOMETERS 44 3 2 4 MULTI LEVEL PIEZOMETERS 47 3 3 STRESS AND PRESSURE MEASUREMENTS 48 3 3 1 BOREHOLE STRESSMETERS 48 3 3 2 PRESSURE CELLS 50 3 4 STRAIN GAUGES 54 3 4 1 SPECI CATIONS 56 3 5 LOAD CELLS 56 3 5 1 SPECI CATIONS 57 3 6 INCLINOMETERS 57 3 6 1 TYPICAL SPECI CATIONS 60 3 7 EXTENSOMETERS 60 3 7 1 TYPICAL SPECI CATIONS 62 3 8 STRUCTURAL DEFORMATION MEASUREMENT 62 3 8 1 CRACKMETER 62 3 8 2 TILTMETER 64 3 9 TEMPERATURE 65 3 9 1 THERMISTOR PROBES 65 3 9 2 THERMISTOR STRINGS 66 3 9 3 TEMPERATURE SENSORS 67 3 10 VIBRATION MONITORING 68 3 11 ALL OTHER TYPES OF GEOTECHNICAL INSTRUMENT 69 4 PLANNING GEOTECHNICAL INSTRUMENTATION PROJECT 73 4 1 DETERMINING ISSUES TO BE SOLVED 73 4 2 DETERMINING KINDS OF MEASUREMENT 74 4 3 OBJECTIVE OF MEASUREMENTS 74 4 4 SELECTING TYPES OF INSTRUMENT TO MONITOR AND COLLECT REQUIRED MEASUREMENTS 76 4 5 SELECTING INSTRUMENT WITH A SUITABLE METHOD OF MEASUREMENT 76 4 6 SELECTING SUITABLE RANGE AND ACCURACY OF MEASUREMENTS 77 4 7 DETERMINING LOCATIONS TO BE INSTALLED 79 4 8 DETERMINING DEPTHS TO INSTALL 82 4 9 DETERMINING TOTAL NUMBERS OF INSTRUMENT REQUIRED FOR EACH TYPE OF INSTRUMENT 83 4 10 PREPARING MONITORING FREQUENCY 83 4 11 PREPARING REMEDIAL PLAN 84 4 11 1 SLOPE INSTABILITY 85 4 11 2 RETAINING WALL INSTABILITY 88 4 11 3 EXCAVATION INSTABILITY 89 4 11 4 GROUND IMPROVEMENT TO ACCELERATE THE CONSOLIDATION PROCESS 89 4 12 BUDGET PREPARATION 90 4 13 PREPARATION OF SPECI CATIONS 91 4 13 1 PERFORMANCE SPECI CATION 91 4 13 2 METHOD SPECI CATION 92 4 14 PROCUREMENT PROCESS 92 4 15 PROTECTION OF INSTALLED INSTRUMENT IN THE LAND RECLAMATION PROJECT 93 5 GEOTECHNICAL INSTRUMENT INSTALLATION 97 5 1 VIBRATING WIRE PIEZOMETER 97 5 1 1 CALIBRATION 97 5 1 2 PREPARATION FOR INSTALLATION 98 5 1 3 INSTALLATION 100 5 1 4 AS BUILT DRAWING 104 5 1 5 INITIAL VERI CATION CHECK 107 5 2 EARTH PRESSURE CELL 109 5 2 1 CALIBRATION 109 5 2 2 PREPARATION FOR INSTALLATION 109 5 2 3 INSTALLATION 109 5 2 4 AS BUILT DRAWING 109 5 2 5 INITIAL VERI CATION CHECK 110 5 3 LOAD CELL 111 5 3 1 CALIBRATION 111 5 3 2 PREPARATION BEFORE INSTALLATION 111 5 3 3 INSTALLATION 112 5 3 4 VERI CATION OF PERFORMANCE 113 5 4 INCLINOMETER 116 5 4 1 CALIBRATION 116 5 4 2 PREPARATION BEFORE INSTALLATION 117 5 4 3 INSTALLATION 117 5 4 4 AS BUILT DRAWING 119 5 5 TILTMETER 120 5 5 1 CALIBRATION 120 5 5 2 PREPARATION BEFORE INSTALLATION 121 5 5 3 INSTALLATION 121 5 5 4 AS BUILT DRAWING 124 5 6 NON ELECTRICAL INSTRUMENT 124 5 7 WATER STANDPIPE 125 5 7 1 INSTALLATION 125 5 7 2 AS BUILT DRAWING 126 5 8 SETTLEMENT PLATE 126 5 8 1 INSTALLATION 126 5 8 2 AS BUILT DRAWING 127 5 9 SETTLEMENT POINT AND MARKER 128 5 9 1 INSTALLATION 128 5 9 2 AS BUILT DRAWING 128 5 10 DEEP SETTLEMENT GAUGES 129 5 10 1 INSTALLATION 129 5 10 2 AS BUILT DRAWINGS 130 5 11 MULTI LEVEL SETTLEMENT GAUGES 130 5 11 1 INSTALLATION 130 5 11 2 AS BUILT DRAWING 131 5 12 DEEP REFERENCE POINT 132 5 12 1 INSTALLATION 132 5 12 2 AS BUILT DRAWING 132 5 13 CRACKMETER 133 5 13 1 INSTALLATION 133 5 13 2 AS BUILT DRAWING 133 5 14 EXTENSOMETER 135 5 14 1 INSTALLATION 135 6 MONITORING DATA PROCESSING DATA VERIFICATION AND PRESENTATION 137 6 1 MONITORING FREQUENCY 138 6 1 1 SETTLEMENT MONITORING 138 6 1 2 LATERAL MOVEMENTS 140 6 1 3 GROUNDWATER LEVEL MEASUREMENTS 144 6 1 4 PORE WATER PRESSURE MEASUREMENTS 148 6 1 5 PRESSURE CELL MONITORING 149 6 1 6 INCLINOMETER MONITORING 149 6 2 DATA PROCESSING 150 6 2 1 DATA PROCESSING FOR SETTLEMENT MONITORING DATA 152 6 2 2 DATA PROCESSING FOR GROUNDWATER LEVEL MONITORING DATA 156 6 2 3 DATA PROCESSING FOR PIEZOMETER MONITORING DATA 158 6 2 4 DATA PROCESSING FOR EARTH PRESSURE MONITORING DATA 169 6 2 5 DATA PROCESSING FOR INCLINOMETER MONITORING DATA 177 6 3 DATA VERI CATION 180 6 3 1 PERFORMANCE VERI CATION OF INITIAL MONITORING DATA FROM VIBRATING WIRE PIEZOMETER 185 6 3 2 PERFORMANCE VERI CATION OF INITIAL MONITORING DATA FROM EARTH PRESSURE CELL 185 6 3 3 PERFORMANCE VERI CATION OF INITIAL MONITORING DATA FROM LOAD CELL 186 6 4 DATA PRESENTATION 186 6 4 1 SETTLEMENT PLATE MONITORING DATA PRESENTATION 187 6 4 2 DEEP SETTLEMENT GAUGES AND MULTI LEVEL SETTLEMENT GAUGES MONITORING DATA PRESENTATION 188 6 4 3 GROUNDWATER MONITORING DATA PRESENTATION 188 6 4 4 PIEZOMETER MONITORING DATA PRESENTATION 191 6 4 5 EARTH PRESSURE MONITORING DATA PRESENTATION 192 6 4 6 INCLINOMETER MONITORING DATA PRESENTATION 194 6 5 DETERMINING ALERT AND TRIGGER LEVELS 194 6 6 AUTOMATIC REAL TIME MONITORING 198 6 7 GEOTECHNICAL DATA ACQUISITION SYSTEMS AND VISUALIZATION SOFTWARE 204 6 7 1 MANUFACTURER SPECI C SOFTWARE 204 6 7 2 MANUFACTURER AGNOSTIC INSTALLER SPECI C SOFTWARE 205 6 7 3 MANUFACTURER AND INSTALLER AGNOSTIC SOFTWARE 205 6 7 4 EXAMPLE OF VISUALIZATION SOFTWARE CAPABILITIES 205 6 8 RECENT ADVANCEMENTS AND THE FUTURE OF MONITORING 206 7 ANALYSES AND PERFORMANCE ASSESSMENT 209 7 1 SETTLEMENTS AND CONSOLIDATION 210 7 1 1 IMMEDIATE SETTLEMENT 210 7 1 2 CONSOLIDATION SETTLEMENT 211 7 2 LATERAL DISPLACEMENT AND SLOPE STABILITY 219 7 2 1 CONTROL OF SLOPE STABILITY USING VERTICAL SETTLEMENT AND HORIZONTAL DISPLACEMENT DATA 221 7 2 2 CONTROL OF SLOPE STABILITY USING HORIZONTAL DISPLACEMENT AND INCREASE IN LOAD 224 7 2 3 CONTROL OF SLOPE STABILITY USING PORE PRESSURE MEASUREMENT DATA 224 7 2 4 CONTROL OF SLOPE STABILITY USING CHANGE IN LATERAL DISPLACEMENT RATE DISPLACEMENT TIME SERIES 226 7 3 EARTH PRESSURES 228 7 4 STRUCTURAL DEFORMATIONS 229 8 FACTORS AFFECTING MEASURED INSTRUMENT DATA 231 8 1 SETTLEMENT MEASUREMENTS 231 8 1 1 SURFACE SETTLEMENT PLATE 231 8 1 2 DEEP SETTLEMENT GAUGE 233 8 1 3 MULTI LEVEL SETTLEMENT GAUGE 233 8 2 BENCH MARK 237 8 3 PORE PRESSURE MEASUREMENTS 238 8 3 1 OVERESTIMATION OR UNDERESTIMATION OF PORE WATER PRESSURES 238 8 4 INCLINOMETER MEASUREMENTS 242 8 5 EARTH PRESSURE MEASUREMENTS 245 9 CASE STUDIES 247 9 1 APPLICATION OF GEOTECHNICAL INSTRUMENTATION IN LAND RECLAMATION AND GROUND IMPROVEMENT 247 9 1 1 INTRODUCTION 247 9 1 2 CHANGI EAST LAND RECLAMATION AND GROUND IMPROVEMENT PROJECTS 248 9 1 3 CONCLUSION 274