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Alternative solution for the in situ stress state inferred from borehole stress relief data
130A 893187 Identification and classification of expansive soils in arid and semi-arid regions Osman, M A: Hamadato. M E M
Proc Ninth Regional Conference for Africa on Soil Mechanics and Foundation Engineering, Lagos, September 1987 V I. P113-116. Publ Rotterdam. A ,4 Balkema. 1987 An indirect method for identification and classification of expansive soils has been developed. Undisturbed soil samples were tested to determine Atterberg limits, shrinkage, clay content, moisture content and swell potential. Linear regression analysis of results shows swell potential is dependent on clay content and shrinkage index. By adopting limits for swell potential, a chart is constructed so that soils may be classified from shrinkage index and clay content. The method is compared with existing methods and application to existing data shows good agreement.
Causes and nature o f in situ stress 893190 State of stress in Spain and its assessment by empirical methods Gonzalez de Vallejo. L I: Serrano, A A; Capote. R. De Vicente, G Proc Symposium on Rock Mechanics and Power Plants, Madrid, 12-16 Sept 1988 VI. P165-172. Publ Rotterdam: A A Balkema. 1988 Methods to assess in situ stress using mathematical analysis and empirical data have been analysed. An acceptable correlation between the relaxation time function expressed in terms of the empirical Stress Relief Factor (SRF) and the ratio of horizontal to vertical in situ stress (K) has been found. Available data on in situ stress in Spain have been re-evaluated. K values estimated by SRF are in the same range as those from overcoring. Directions of principal stress determined by fault or focal mechanisms agree well with those from overcoring.
Measurement o f in situ stress
In Situ Stress
See also: 893233 893191 In situ measurement of vertical and horizontal stress from a vertical borehole. Technical note Watts, K S; Charles, J A
See also: 893416
Geotechnique V38, N4. Dec 1988. P619-626 893188 in situ rock stresses and their measurement in the UK - Part I. The current state of knowledge Hudson, J A; Cooling, C M
Int J Rock Mech Min Sci V25. N6. Dec 1988. P363-370 The current state of knowledge of rock stresses in the UK is discussed. Stress is a tensor with 6 components which may be measured using a flatjack, hydraulic fracturing, USBM gauge and CSIRO gauge. The effect of excavation on in situ stresses is outlined. Problems in measuring in situ stress, due to rock structure-rock stress interaction, measurement techniques and data reduction, are discussed. Some conclusions about rock stresses in the UK are outlined.
893189 In situ rock stresses and their measurement in the UK - Part II. Site experiments and field stress interpretation Cooling, C M; Hudson, J A: Tunbridge, L W
lnt J Rock h4ech Min Sci V25. N6, Dec 1988, P371-382 A suite of in situ stress measurements made at a test site in the Carnmenellis granite in Cornwall is described and results compared with those obtained from other sites within this granite. The various techniques of overcoring and the hydraulic fracturing method employed are compared, their limitations and strengths noted and the resulting measurements assessed. An interpretation of the measured stress field in the light of the geological history and the structural and regional provenance of the granite is attempted. The results of subsequent in situ stress measurements undertaken at other sites in the UK are evaluated and compared with those from Cornwall. The wider implications and possible extensions of the work are considered. Auth.
A miniature earth pressure cell has been designed to be jacked horizontally into soft clay of the vertical wall of a borehole to measure vertical stress. Installation equipment and procedure are described, and calibration outlined. The device was used to examine earth pressures within puddle clay cores of old embankment dams and vertical stress under a loading pad, which showed it gives similar values to larger spade-shaped cells. 893192 Analysis and modelling of holographic measurements of in situ stress Smither, C L; Schmitt, D R; Ahrens, T J
Int J Rock Mech Min Sci V25, N6, Dec 1988, P353-362 In situ stress measurements were made on the walls of a borehole at 5 different azimuths at a single location using a holographic stress meter. Values derived were used to determine all 6 components of the far field stress tensor in a mine pillar using the least squares inversion method. A finite element program was developed to predict the displacement field due to drilling the stress relief hole, and predictions compared with an analytical solution for a hole in a stressed plate, used in analysis of the holograms. This shows the depth of a stress relief hole is more important in determining total displacement field than suggested by the analytical place model. 893193 Alternative solution for the in situ stress state inferred from borehole stress relief data Pariseau, W G
Proc 6th International Conference on Rock Mechanics, Montreal, 30 Aug-lO Sept 1987 I,'2, P1201-1205. Publ Rotterdam: A ,4 Balkema, 1987 Conventional analysis of stress around a long cylindrical opening in linearly elastic rock, which is the basis of stress measurement by the overcoring method, is re-examined and
~ 1989 Pergamon Press plc. Reproduction not permitted
131A shown to be in error. The correct solution is given. Compensating errors are found, which mean that for all practical purposes inaccuracies arising are negligible, at least in isotropic ground.
Site Investigation and Field Observation 893194 Special lecture: applicability and usefulness of field measurements on unstable slopes Krauter, E Proc 5th International Symposium on Landslides, Lausanne, 10-15 July 1988 VI, t'367-373. Publ Rotterdam: A A Balkema, 1988
893197 Photointerpretation method of landslides forecasting Lenczewska, E Proc 5th International Symposium on Landslides, Lausanne, 10-15 July 1988 VI, P443-444. Publ Rotterdam: A A Balkema, 1988 A method to predict landslide movement in the clayey slate flysch of the Carpathian mountains has been developed. Aerial photographs are closely analysed, to identify areas where the tone is darker. This is indicative of higher water content. The degree of clarity of the darker toned area may be used to predict timing of the slide.
Structural and geotechnical mapping 893198 Prediction and detection of potential high-permeabifity zones within the Alabama coastal plain chalky marls: Technical note. Bittner, E; Holston, I; King, D T Bull Assoe Engng Geol V25, N4, Nov 1988, 1'508-514
Engineering geophysical measurements used in the broadest sense to collect field data for the analysis of slope stability are described and their applicability discussed. Mechanical measuring methods, spies, extensometer, inclinometer, and soundings, and engineering geophysical methods, hammer-blow seismic, geoclectric, radar, acoustic soundings, and soil-gas measurements, are outlined. Geodetic measurements are described. Interpretation of field measurements on unstable slopes is explained.
Remote sensing and geophysical techniques were used to predict and detect zones of high permeability, due to fracturing, of the low permeability rocks. Fracture traces were mapped as lineaments on aerial photographs and straight-stream sections on topographic maps. Electrical resistivity tests were performed. The methods successfully predicted zones of permeability related to fracturing.
Remote sensing and photographic techniques
893199 Earthquake site response study of Accra area, Ghana Ayetey, J K; Andoh, M B lnt Assoc Engng Geol Bull N38, Oct 1988, P15-25
893195 Detection of buried placer deposits by ground magnetic survey Schwarz, E J; Wright, N Geophys Prospect V36. Ng, Not" 1988, P919-932 Placers may be buried in alluvial gravels, sands, or clays of the river terrace or be covered by glacial till. An inexpensive magnetometer method has been developed to find such placers from the surface without drilling or prior knowledge of promising areas. Computer model response of the magnetic signal due to the placer is first examined. Instrumentation and test results and their interpretation are then considered. The technique is seen to be able to delineate areas of interest for exploration from low level airborne surveys.
893196 Case studies on landslides in Wynad region of western Ghats, peninsular India Jayakumar, M; Vinayan, P K Proc 5th International Symposium on Landslides, Lausanne, 10-15 July 1988 VI, P433-437. Publ Rotterdam: A A Balkema, 1988 A study area in the Western Ghats has been analysed to assess possible parameters causing landslides. Landsat imagery and aerial photography were used to determine areas susceptible to landsliding by delineating differences in vegetation and soil moisture, and unique characteristics of terrain in terms of geology, geomorphology and drainage structure. This led to the identification of several susceptible areas, which were verified using field surveys. Unconfined compression tests were used to evaluate qualitative loss in strength due to an increase in moisture content.
The geology and soil mechanical properties of the area were examined as a basis for mapping seismic risk and damage degree zones, which will act as a planning aid and give some prior information to site engineers. Engineering soils distribution, bedrock geology and topography, groundwater conditions, and past earthquake records were all included in the analysis to prepare the maps. 893200 Using isopleth mapping to evaluate landslide activity in relation to agricultural practices De Graft, J V; Canuti, P lnt Assoc Engng Geol Bull N38, Oct 1988. P61-71 The use of isopleth maps for landslide hazard assessment and zonation is illustrated using 2 examples. The isopleth map uses topography and location of known landslides for assessment, and can provide a qualitative comparison of landslide activity between different parts of an area. In the Arno Valley; Italy, the maps were used to assess the change in landslide activity due to changes in agricultural practices, whilst in the Sierra National Forest, California, the maps are used for hazard zoning to aid in timber sales. 893201 Microcomputers used as an aid for geological mapping (In French) Durand, M int Assoc Engng Geoi Bull N38, Oct 1988, P73-82 An approach to computerised geological mapping is presented in which a standard microcomputer is used mainly as an assistant in various stages of storing, analysis and plotting of the spatially distributed geological data. The graphical interactive analysis on the screen, with powerful tools for drawing and referencing each geological or geotechnical element,aids but
© 1989 Pergamon Press plc. Reproduction not permitted
Proc Ninth Regional Conference for Africa on Soil Mechanics and Foundation Engineering, Lagos, September 1987 V I. P113-116. Publ Rotterdam. A ,4 Balkema. 1987 An indirect method for identification and classification of expansive soils has been developed. Undisturbed soil samples were tested to determine Atterberg limits, shrinkage, clay content, moisture content and swell potential. Linear regression analysis of results shows swell potential is dependent on clay content and shrinkage index. By adopting limits for swell potential, a chart is constructed so that soils may be classified from shrinkage index and clay content. The method is compared with existing methods and application to existing data shows good agreement.
Causes and nature o f in situ stress 893190 State of stress in Spain and its assessment by empirical methods Gonzalez de Vallejo. L I: Serrano, A A; Capote. R. De Vicente, G Proc Symposium on Rock Mechanics and Power Plants, Madrid, 12-16 Sept 1988 VI. P165-172. Publ Rotterdam: A A Balkema. 1988 Methods to assess in situ stress using mathematical analysis and empirical data have been analysed. An acceptable correlation between the relaxation time function expressed in terms of the empirical Stress Relief Factor (SRF) and the ratio of horizontal to vertical in situ stress (K) has been found. Available data on in situ stress in Spain have been re-evaluated. K values estimated by SRF are in the same range as those from overcoring. Directions of principal stress determined by fault or focal mechanisms agree well with those from overcoring.
Measurement o f in situ stress
In Situ Stress
See also: 893233 893191 In situ measurement of vertical and horizontal stress from a vertical borehole. Technical note Watts, K S; Charles, J A
See also: 893416
Geotechnique V38, N4. Dec 1988. P619-626 893188 in situ rock stresses and their measurement in the UK - Part I. The current state of knowledge Hudson, J A; Cooling, C M
Int J Rock Mech Min Sci V25. N6. Dec 1988. P363-370 The current state of knowledge of rock stresses in the UK is discussed. Stress is a tensor with 6 components which may be measured using a flatjack, hydraulic fracturing, USBM gauge and CSIRO gauge. The effect of excavation on in situ stresses is outlined. Problems in measuring in situ stress, due to rock structure-rock stress interaction, measurement techniques and data reduction, are discussed. Some conclusions about rock stresses in the UK are outlined.
893189 In situ rock stresses and their measurement in the UK - Part II. Site experiments and field stress interpretation Cooling, C M; Hudson, J A: Tunbridge, L W
lnt J Rock h4ech Min Sci V25. N6, Dec 1988, P371-382 A suite of in situ stress measurements made at a test site in the Carnmenellis granite in Cornwall is described and results compared with those obtained from other sites within this granite. The various techniques of overcoring and the hydraulic fracturing method employed are compared, their limitations and strengths noted and the resulting measurements assessed. An interpretation of the measured stress field in the light of the geological history and the structural and regional provenance of the granite is attempted. The results of subsequent in situ stress measurements undertaken at other sites in the UK are evaluated and compared with those from Cornwall. The wider implications and possible extensions of the work are considered. Auth.
A miniature earth pressure cell has been designed to be jacked horizontally into soft clay of the vertical wall of a borehole to measure vertical stress. Installation equipment and procedure are described, and calibration outlined. The device was used to examine earth pressures within puddle clay cores of old embankment dams and vertical stress under a loading pad, which showed it gives similar values to larger spade-shaped cells. 893192 Analysis and modelling of holographic measurements of in situ stress Smither, C L; Schmitt, D R; Ahrens, T J
Int J Rock Mech Min Sci V25, N6, Dec 1988, P353-362 In situ stress measurements were made on the walls of a borehole at 5 different azimuths at a single location using a holographic stress meter. Values derived were used to determine all 6 components of the far field stress tensor in a mine pillar using the least squares inversion method. A finite element program was developed to predict the displacement field due to drilling the stress relief hole, and predictions compared with an analytical solution for a hole in a stressed plate, used in analysis of the holograms. This shows the depth of a stress relief hole is more important in determining total displacement field than suggested by the analytical place model. 893193 Alternative solution for the in situ stress state inferred from borehole stress relief data Pariseau, W G
Proc 6th International Conference on Rock Mechanics, Montreal, 30 Aug-lO Sept 1987 I,'2, P1201-1205. Publ Rotterdam: A ,4 Balkema, 1987 Conventional analysis of stress around a long cylindrical opening in linearly elastic rock, which is the basis of stress measurement by the overcoring method, is re-examined and
~ 1989 Pergamon Press plc. Reproduction not permitted
131A shown to be in error. The correct solution is given. Compensating errors are found, which mean that for all practical purposes inaccuracies arising are negligible, at least in isotropic ground.
Site Investigation and Field Observation 893194 Special lecture: applicability and usefulness of field measurements on unstable slopes Krauter, E Proc 5th International Symposium on Landslides, Lausanne, 10-15 July 1988 VI, t'367-373. Publ Rotterdam: A A Balkema, 1988
893197 Photointerpretation method of landslides forecasting Lenczewska, E Proc 5th International Symposium on Landslides, Lausanne, 10-15 July 1988 VI, P443-444. Publ Rotterdam: A A Balkema, 1988 A method to predict landslide movement in the clayey slate flysch of the Carpathian mountains has been developed. Aerial photographs are closely analysed, to identify areas where the tone is darker. This is indicative of higher water content. The degree of clarity of the darker toned area may be used to predict timing of the slide.
Structural and geotechnical mapping 893198 Prediction and detection of potential high-permeabifity zones within the Alabama coastal plain chalky marls: Technical note. Bittner, E; Holston, I; King, D T Bull Assoe Engng Geol V25, N4, Nov 1988, 1'508-514
Engineering geophysical measurements used in the broadest sense to collect field data for the analysis of slope stability are described and their applicability discussed. Mechanical measuring methods, spies, extensometer, inclinometer, and soundings, and engineering geophysical methods, hammer-blow seismic, geoclectric, radar, acoustic soundings, and soil-gas measurements, are outlined. Geodetic measurements are described. Interpretation of field measurements on unstable slopes is explained.
Remote sensing and geophysical techniques were used to predict and detect zones of high permeability, due to fracturing, of the low permeability rocks. Fracture traces were mapped as lineaments on aerial photographs and straight-stream sections on topographic maps. Electrical resistivity tests were performed. The methods successfully predicted zones of permeability related to fracturing.
Remote sensing and photographic techniques
893199 Earthquake site response study of Accra area, Ghana Ayetey, J K; Andoh, M B lnt Assoc Engng Geol Bull N38, Oct 1988, P15-25
893195 Detection of buried placer deposits by ground magnetic survey Schwarz, E J; Wright, N Geophys Prospect V36. Ng, Not" 1988, P919-932 Placers may be buried in alluvial gravels, sands, or clays of the river terrace or be covered by glacial till. An inexpensive magnetometer method has been developed to find such placers from the surface without drilling or prior knowledge of promising areas. Computer model response of the magnetic signal due to the placer is first examined. Instrumentation and test results and their interpretation are then considered. The technique is seen to be able to delineate areas of interest for exploration from low level airborne surveys.
893196 Case studies on landslides in Wynad region of western Ghats, peninsular India Jayakumar, M; Vinayan, P K Proc 5th International Symposium on Landslides, Lausanne, 10-15 July 1988 VI, P433-437. Publ Rotterdam: A A Balkema, 1988 A study area in the Western Ghats has been analysed to assess possible parameters causing landslides. Landsat imagery and aerial photography were used to determine areas susceptible to landsliding by delineating differences in vegetation and soil moisture, and unique characteristics of terrain in terms of geology, geomorphology and drainage structure. This led to the identification of several susceptible areas, which were verified using field surveys. Unconfined compression tests were used to evaluate qualitative loss in strength due to an increase in moisture content.
The geology and soil mechanical properties of the area were examined as a basis for mapping seismic risk and damage degree zones, which will act as a planning aid and give some prior information to site engineers. Engineering soils distribution, bedrock geology and topography, groundwater conditions, and past earthquake records were all included in the analysis to prepare the maps. 893200 Using isopleth mapping to evaluate landslide activity in relation to agricultural practices De Graft, J V; Canuti, P lnt Assoc Engng Geol Bull N38, Oct 1988. P61-71 The use of isopleth maps for landslide hazard assessment and zonation is illustrated using 2 examples. The isopleth map uses topography and location of known landslides for assessment, and can provide a qualitative comparison of landslide activity between different parts of an area. In the Arno Valley; Italy, the maps were used to assess the change in landslide activity due to changes in agricultural practices, whilst in the Sierra National Forest, California, the maps are used for hazard zoning to aid in timber sales. 893201 Microcomputers used as an aid for geological mapping (In French) Durand, M int Assoc Engng Geoi Bull N38, Oct 1988, P73-82 An approach to computerised geological mapping is presented in which a standard microcomputer is used mainly as an assistant in various stages of storing, analysis and plotting of the spatially distributed geological data. The graphical interactive analysis on the screen, with powerful tools for drawing and referencing each geological or geotechnical element,aids but
© 1989 Pergamon Press plc. Reproduction not permitted