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Rate effects in pressuremeter tests in clays
II5A
Time dependent behaviour See also: 883357 883O83 Viseopinstic model for geologic materials with generalized flow rule Dcsai, C S; Zhang, D lnt J Nnm Anal Meth Geomech V11, N6, Nov-Dec 1987, P603-620
The general yield function in the hierarchical approach for constitutive modelling of materials is used with Perzyna's theory to characterise viscoplastic behaviour of a soil and rock salt. Constants are derived from quasistatic and creep tests in the laboratory. The model is verified using the stress strain response of a soil and rock salt, and illustrated using a finite element procedure to predict the viseoplastic behaviour of a cavity in rock salt. 883O84 Lob-term strength of plutenic rock. Technical note Wilkins, B J S lnt J Rock Meek Min Sci V24, N6, Dec 1987, P379-380
Models to assess the extent of microcrack extension in a rock mass due to mechanical or thermal loading have been formulated. Experimental data from rock beams loaded in fourpoint bending were used to derive A and n, the constants in the models. Comparison with uniaxial measurements on granite shows n is independent of the mode of loading. 883085 Rate effects in premuremeter tests in days Anderson, W F; Pyrah, I C J Geoteck Eogng Die ASCE V113, N i l , Nov 1987, P13441358
A modified triaxial cell is used to simulate a high quality, self boring prcssurcmeter test. Expansion and strcss-strain curves show that, at early stages of expansion, longer holding time leads to greater deformation, although this trend tends to reverse at larger radial strains. These results were compared with a finite element analysis, studying local consolidation effects independent of other time dependent effects such as creep. This gives new insight into clay behaviour during pressuremeter tests and indicates simple standardisation of prcssuremeter test technique should be approached with caution. 883086 Stable and unstable geostatic anomalies in the case of salt, a study by centrifuge simulation (In French) Zelikson, A R ~ Fr Geoteck N41, 1987, t'45-61
As part of the program to find safe sites for nuclear waste disposal, the triggering and growth of salt domes was investigated in the laboratory, using centrifuge modelling. Soft solids (clays, gelatine) were used to represent the salt and rocks. Similitude is based on the Bingham model. Deformations were filmed and stresses measured using photoclasticity. The safety of various configurations was studied. 883087 Effect of simulated sampling disturbance on creep behaviour of
rock salt Guessous, Z; Gill, D E; Ladanyi, B Rock Meek Rock Eogsg V20, N4, Oct-Dec 1987, P261-275 Laboratory-determined mechanical properties of a rock mass arc not necessarily representative of those in situ. The laboratory-determined creep behaviour of rock salt is examined as a
function of the degree of prestrain, simulating sample disturbance. Radial compression tests simulated prestrain. Results indicate that, in the short term, creep behaviour is strongly affected by preloading history, but this decreases rapidly over time. 883O88 Analysis of the damage of the structure caused by the freezing and thawing of the sulmoil Li Ya Li; Bao, Y H Proc 5th Internatio~ud Congress lnterMtimud Association of Eogineerimg Geology, Buemos Aires, 20-25 October 1936 V2, P923-929. Pubi Rotterdam: A A Balkema, 1986
Settlement of a cold storage building on pile foundations in clay soil in China has been studied. Results suggest that the settlement of the freezing and thawing soil has two components, thawing and compression settlement as according to Tsytovich and settlement of the whole frozen body of the soil as a mat foundation. The destructive effect of the freeze-thaw cycling on the surface structure was also investigated.
Physico-chemical properties See also: 883389 883089 Anisotropy of magnetic mmceptibility (ASM) and magnetic fabric of a rock (In French) Vergne, R Ann Geophys VSB, N6, Dec 1987, P595-600
It is shown that the magnetic behaviour of a polycrystalline rock can be equated to that of a linear medium with an anisotropic magnetic susceptibility which can be described by a symmetrical tensor of rank 2, and which allows a magnetic fabric to be defined. A complex susceptibility is defined. By varying the polarisation field, it is possible to some extent to separate contributions of linear and highly ordered components. 883O90 Thermal properties of sweln~, day soils Ross, P J; Bridge, B J Aust J Soil Res V25, N1, 1987, P29-41
The pulse method was used to measure the thermal diffusivity of a swelling soil. Thermal conductivity was calculated from diffusivity and heat capacity per unit volume. Compared to non-swelling soils, calculated conductivities were lower at low water content, increased less with water content, and eventually decreased as the soil became saturated and swelled. Results arc examined against predictions of three soil models. 883091 Thermal diffnsivity of igneous rocks at elevated premmm and temperature Durham, W B; Mirkovich, V V; Heard, H C J Geophys Res V92, NBI1, Oct 1987, P11615-11634
The thermal diffusivity of 7 low-porosity igneous rocks was measured at temperatures and pressur~ ranging from 30-400 deg C and 0.1-200MPa respectively. Results indicate: (1) thermal diffnsivity of all the rocks shows linear variation with inverse temperature; (2) thermal diffnsivity of all except a gabbro shows linear dependence on quartz content; (3) thermal diffusivity rises with increasing pressure but the character of pressure dependence varies. Granitic rocks show stronger pressure dependence than basaltic rocks.
© 1988 Pergamon Press pic. Reproduction not permitted
Time dependent behaviour See also: 883357 883O83 Viseopinstic model for geologic materials with generalized flow rule Dcsai, C S; Zhang, D lnt J Nnm Anal Meth Geomech V11, N6, Nov-Dec 1987, P603-620
The general yield function in the hierarchical approach for constitutive modelling of materials is used with Perzyna's theory to characterise viscoplastic behaviour of a soil and rock salt. Constants are derived from quasistatic and creep tests in the laboratory. The model is verified using the stress strain response of a soil and rock salt, and illustrated using a finite element procedure to predict the viseoplastic behaviour of a cavity in rock salt. 883O84 Lob-term strength of plutenic rock. Technical note Wilkins, B J S lnt J Rock Meek Min Sci V24, N6, Dec 1987, P379-380
Models to assess the extent of microcrack extension in a rock mass due to mechanical or thermal loading have been formulated. Experimental data from rock beams loaded in fourpoint bending were used to derive A and n, the constants in the models. Comparison with uniaxial measurements on granite shows n is independent of the mode of loading. 883085 Rate effects in premuremeter tests in days Anderson, W F; Pyrah, I C J Geoteck Eogng Die ASCE V113, N i l , Nov 1987, P13441358
A modified triaxial cell is used to simulate a high quality, self boring prcssurcmeter test. Expansion and strcss-strain curves show that, at early stages of expansion, longer holding time leads to greater deformation, although this trend tends to reverse at larger radial strains. These results were compared with a finite element analysis, studying local consolidation effects independent of other time dependent effects such as creep. This gives new insight into clay behaviour during pressuremeter tests and indicates simple standardisation of prcssuremeter test technique should be approached with caution. 883086 Stable and unstable geostatic anomalies in the case of salt, a study by centrifuge simulation (In French) Zelikson, A R ~ Fr Geoteck N41, 1987, t'45-61
As part of the program to find safe sites for nuclear waste disposal, the triggering and growth of salt domes was investigated in the laboratory, using centrifuge modelling. Soft solids (clays, gelatine) were used to represent the salt and rocks. Similitude is based on the Bingham model. Deformations were filmed and stresses measured using photoclasticity. The safety of various configurations was studied. 883087 Effect of simulated sampling disturbance on creep behaviour of
rock salt Guessous, Z; Gill, D E; Ladanyi, B Rock Meek Rock Eogsg V20, N4, Oct-Dec 1987, P261-275 Laboratory-determined mechanical properties of a rock mass arc not necessarily representative of those in situ. The laboratory-determined creep behaviour of rock salt is examined as a
function of the degree of prestrain, simulating sample disturbance. Radial compression tests simulated prestrain. Results indicate that, in the short term, creep behaviour is strongly affected by preloading history, but this decreases rapidly over time. 883O88 Analysis of the damage of the structure caused by the freezing and thawing of the sulmoil Li Ya Li; Bao, Y H Proc 5th Internatio~ud Congress lnterMtimud Association of Eogineerimg Geology, Buemos Aires, 20-25 October 1936 V2, P923-929. Pubi Rotterdam: A A Balkema, 1986
Settlement of a cold storage building on pile foundations in clay soil in China has been studied. Results suggest that the settlement of the freezing and thawing soil has two components, thawing and compression settlement as according to Tsytovich and settlement of the whole frozen body of the soil as a mat foundation. The destructive effect of the freeze-thaw cycling on the surface structure was also investigated.
Physico-chemical properties See also: 883389 883089 Anisotropy of magnetic mmceptibility (ASM) and magnetic fabric of a rock (In French) Vergne, R Ann Geophys VSB, N6, Dec 1987, P595-600
It is shown that the magnetic behaviour of a polycrystalline rock can be equated to that of a linear medium with an anisotropic magnetic susceptibility which can be described by a symmetrical tensor of rank 2, and which allows a magnetic fabric to be defined. A complex susceptibility is defined. By varying the polarisation field, it is possible to some extent to separate contributions of linear and highly ordered components. 883O90 Thermal properties of sweln~, day soils Ross, P J; Bridge, B J Aust J Soil Res V25, N1, 1987, P29-41
The pulse method was used to measure the thermal diffusivity of a swelling soil. Thermal conductivity was calculated from diffusivity and heat capacity per unit volume. Compared to non-swelling soils, calculated conductivities were lower at low water content, increased less with water content, and eventually decreased as the soil became saturated and swelled. Results arc examined against predictions of three soil models. 883091 Thermal diffnsivity of igneous rocks at elevated premmm and temperature Durham, W B; Mirkovich, V V; Heard, H C J Geophys Res V92, NBI1, Oct 1987, P11615-11634
The thermal diffusivity of 7 low-porosity igneous rocks was measured at temperatures and pressur~ ranging from 30-400 deg C and 0.1-200MPa respectively. Results indicate: (1) thermal diffnsivity of all the rocks shows linear variation with inverse temperature; (2) thermal diffnsivity of all except a gabbro shows linear dependence on quartz content; (3) thermal diffusivity rises with increasing pressure but the character of pressure dependence varies. Granitic rocks show stronger pressure dependence than basaltic rocks.
© 1988 Pergamon Press pic. Reproduction not permitted