- Email: [email protected]
Evaluation of design parameters for earth tunnels
339A examined. Frictional angle increases with increasing density. A consistent, though small, drop in cohesion was seen for reactivation. 916064 Defining material response with the uniaxial-biaxiai test Lupo, J F; Patti, N C; Thompson, T W Rock Mechanics Contributions and Challenges: Proc 31st US Symposium, Golden, 18-20 June 1990 P597-604. Publ Rotterdam: A A Balkema, 1990 Strain path tests allow generation of continuous data on material response over a wide range of stress levels. Combination of uniaxial and biaxial tests allows continuously yielding nature to be described and the determination of position and shape of the failure envelope using a single specimen. The test begins with uniaxial strain loading path at constant axial strain rate, with confining pressure gradually increased so as to maintain zero transverse strain. Biaxial unload follows the uniaxial loading path. Data for drained response of weak concrete and undrained response of saturated simulated rock are presented. 916065 Moisture effects and the mechanical response of granite beams Labuz, J F; Berger, D J Rock Mechanics Contributions and Challenges: Proc 31st US Symposium, Golden, 18-20 June 1990 P605-611. Publ Rotterdam: A A Balkema, 1990 Load displacement behaviour of chevron notched round bar specimens of Charcoal granite in bending has been studied in the laboratory. Stiffness can be drastically lowered by wetting from air-dried state and increased by drying by heating. This may be associated with the expansion of the granite on wetting. The modulus of Charcoal granite is some 20% larger in compression than in tension. It is therefore suggested that tensile prestrain due to moisture softens the response of the beams. 916O66 High pressure embrittlement and shear-enhanced compaction of Berea sandstone: acoustic emission measurement and microstructural observation Zhang, J; Wong, T F; Davis, D M Rock Mechanics Contributions and Challenges: Proc 31st US Symposium, Golden, 18-20 June 1990 P653-660. Publ Rotterdam: A A Balkema, 1990 Triaxial tests on Berea sandstone at confining pressures to 460MPa, constant pore pressure 10MPa, enabled the brittle to ductile transition and high pressure embrittlement to be followed. AE measurement and SEM studies were used to examine the micromechanics of the deformation. Grain crushing and pore collapse resulting from grain scale microcracking were dominant in high pressure deformation. As mean effective stress increased,so did differential stress at onset of shearenhanced compaction. A linear relation between degree of porosity reduction and cumulative number of AE events during deformation was observed. 916067 Indentation by pore collapse in porous rocks Suarez-Rivera, F R; Cook, N G W; Cooper, G A Rock Mechanics Contributions and Challenges: Proc 31st US Symposium, Golden, 18-20 June 1990 P671-678. Publ Rotterdam." A A Balkema, 1990 Indentation experiments were carried out on Berea sandstone, Indiana limestone, and porous refractory brick specimens. Compaction in the region of the indenter is seen to be of primary importance in the indentation. Porosity of rock and
strength of the pore structure control the extent of the compaction zone. Refractory brick specimens failed exclusively by pore collapse, and their behaviour is used to visualise the development of the compaction zone free from influence of other modes of failure. Rock compaction effects on efficiency of drilling with roller cone bits in porous rocks are discussed. 916068 Rain-induced slope slides of residual soils in Hong Kong Ting Hu Proc 2nd International Conference on Foundations and Tunnels, London, 19-21 September 1989 V2, P215-217. Pub l Edinburgh." Engineering Technics Press, 1989 Soil and climatic conditions in Hong Kong are briefly summarised. The effect of prolonged rainfall on the stress state of the soil is examined considering variations in pore air and water pressures and their influence on effective shear strength. Reduction of strength leading up to slope failure is considered. The limit equilibrium method is suggested for slope design. Engineering measures to reduce likelihood of rainfall induced failure are suggested. 916069 Pore water pressure monitoring during the screw plate testing in a soft clay Bauer, G E Proc International Symposium on Computer and Physical Modelling in Geoteehaical Engineering, Bangkok, 3-6 December 1986 P269-278. Publ Rotterdam: A A Balkema, 1989 In situ tests using a screw plate test device were conducted in order to analyse porewater pressure responses. A total of twenty screw plate tests was carried out in four boreholes to a maximum depth of 10m. Equipment is illustrated. Slow and rapid tests were carried out to obtain drained and undrained parameters, 916070 Instability and failure of soils with nonassociated flow Lade, P V Proc 12th International Conference on Soil Meclutm'cs and Foundation Engineering, Rio de Janeiro, 13-18 August 1989 V1, P727-730. Publ Rotterdam." A A Balkema, 1989 Materials exhibiting nonassociated flow may become unstable within the failure surface under certain stress paths, according to the stability postulates of Drucker and Hill. Triaxial tests on granular materials were carried out to examine this possibility. At low confining pressures the material dilates and is stable, violating both stability postulates. At high confining pressure the material compresses and unstable behaviour is seen inside the failure surface. The need to recognise and understand factors controlling unstable behaviour is emphasised. 916071 Nonlinear failure envelope for coarse grained soils Maksimovic, M Proc 12th International Conference on Soil Mechanics and Foundation Engineering, Rio de Janeiro, 13-18 August 1989 V1, P731-734. Publ Rotterdam: A A Balkema, 1989 A description is obtained for the nonlinear failure envelope, in terms of effective stress, applicable for most non-cemented granular materials. It consists of components relating to base angle of friction, maximum contribution of dilatancy, and median angle normal stress. Some published test results are described in terms of those parameters, and typical ranges for these parameters are presented for materials from sands to rock fill.
© 1991 Pergamon Press plc. Reproduction not permitted
strength of the pore structure control the extent of the compaction zone. Refractory brick specimens failed exclusively by pore collapse, and their behaviour is used to visualise the development of the compaction zone free from influence of other modes of failure. Rock compaction effects on efficiency of drilling with roller cone bits in porous rocks are discussed. 916068 Rain-induced slope slides of residual soils in Hong Kong Ting Hu Proc 2nd International Conference on Foundations and Tunnels, London, 19-21 September 1989 V2, P215-217. Pub l Edinburgh." Engineering Technics Press, 1989 Soil and climatic conditions in Hong Kong are briefly summarised. The effect of prolonged rainfall on the stress state of the soil is examined considering variations in pore air and water pressures and their influence on effective shear strength. Reduction of strength leading up to slope failure is considered. The limit equilibrium method is suggested for slope design. Engineering measures to reduce likelihood of rainfall induced failure are suggested. 916069 Pore water pressure monitoring during the screw plate testing in a soft clay Bauer, G E Proc International Symposium on Computer and Physical Modelling in Geoteehaical Engineering, Bangkok, 3-6 December 1986 P269-278. Publ Rotterdam: A A Balkema, 1989 In situ tests using a screw plate test device were conducted in order to analyse porewater pressure responses. A total of twenty screw plate tests was carried out in four boreholes to a maximum depth of 10m. Equipment is illustrated. Slow and rapid tests were carried out to obtain drained and undrained parameters, 916070 Instability and failure of soils with nonassociated flow Lade, P V Proc 12th International Conference on Soil Meclutm'cs and Foundation Engineering, Rio de Janeiro, 13-18 August 1989 V1, P727-730. Publ Rotterdam." A A Balkema, 1989 Materials exhibiting nonassociated flow may become unstable within the failure surface under certain stress paths, according to the stability postulates of Drucker and Hill. Triaxial tests on granular materials were carried out to examine this possibility. At low confining pressures the material dilates and is stable, violating both stability postulates. At high confining pressure the material compresses and unstable behaviour is seen inside the failure surface. The need to recognise and understand factors controlling unstable behaviour is emphasised. 916071 Nonlinear failure envelope for coarse grained soils Maksimovic, M Proc 12th International Conference on Soil Mechanics and Foundation Engineering, Rio de Janeiro, 13-18 August 1989 V1, P731-734. Publ Rotterdam: A A Balkema, 1989 A description is obtained for the nonlinear failure envelope, in terms of effective stress, applicable for most non-cemented granular materials. It consists of components relating to base angle of friction, maximum contribution of dilatancy, and median angle normal stress. Some published test results are described in terms of those parameters, and typical ranges for these parameters are presented for materials from sands to rock fill.
© 1991 Pergamon Press plc. Reproduction not permitted