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Soil stress measurement under rigid wheel loading
PROPERTIESzDYNAMICS processes leads to the conclusion that both processes are more or less reversible. (Authors) 956139 One-dimensionrl water transport in covercrete - application of non-destructive methods J. Kaufmann & W. Studer, Materials & Structures, 28(176), 1995, pp 115-123. One-dimensional water transport in cores of different concrete types with a moulded surface at one end was investigated by the simple measurement of mass changes during suction and by evaporation tests. Nondestructive methods (magnetic resonance imaging (MRI) and X-ray tomography) were applied successfully to the localization of water distribution within the concrete during such tests. Before the suction test was carried out, all samples were stored for 18 months under constant climatic conditions to avoid inhomogeneous humidity distributions. They were then sealed with aluminium tape (epoxy in the MRI measurement) on all faces except the moulded surface, thus guaranteeing one-dimensional flow. (Authors)
Compression, swelling and consolidation 956140 Energy anply& of fdte element soil stress prediction W. A. Block, C. E. Johnson, A. C. Bailey, E. C. Burt & R. L. Raper, Transactions - American Society of Agricultural Engineers, 37(6), 1994, pp 1757-1762. Soil stresses under a rigid wheel loading were predicted with a finite element model using each of three different soil compaction models as the constitutive relationship. An energy analysis compared the energy lost in traction to energy absorbed in compaction as predicted by the finite element model. One constitutive relationship resulted in underprediction of energy absorbed in compaction while the other two resulted in overprediction. The method of energy analysis is shown to be a useful tool for evaluating accuracy of soil stress and strain predictions by a finite element model. (Authors) 956141 Soil stress measmrement under rigid wheel loading W. A. Block, C. E. Johnson, A. C. Bailey, E. C. Burt & R. L. Raper, Transactions - American Society of Agricultural Engineers, 37(6), 1994, pp 1753-1756. Understanding soil response to compactive forces may help in deciding how to manage the adverse effects such as soil erosion. Soil stress states were measured beneath the path of a rigid wheel. A multivariate analysis of variance was conducted on the data to determine the effect on stress state caused by dynamic and tractive wheel loads, in different soil types and with or without the presence of a hardpan. (from Authors) 956142 Boundary element analysis of stresses in an axisymmetric soil mass undergoing consolidation M. B. Chopra & G. F. Dargush, International Journal for Numerical & Analytical Methods in Geomechanics, 19(3), 1995, pp 195-218. A time domain boundary element method (BEM) for evaluating stresses in an axisymmetric soil mass undergoing consolidation has been developed. Previous BEM work is extended to permit the computation of stresses at both boundary and interior points. The stress formulation pre.serves the surface-only discretization. The boundary displa-
269A
cement integral equation is progressively differentiated to obtain the related stress and strain integral equations. Explicit expressions for the steady-state axisymmetric fundamental solutions are derived in this process. The transient components of the integrands are obtained directly from the transformation of the three-dimensional kernels into a cylindrical system. Numerical implication is carried out within a general purpose BEM computer code and examples are presented to validate the method. (Authors)
956143 Settlement analysis by the ‘moving Iimit depth’ model P. Scharle, Periodica Polytechnica: Civil Engineering, 38( 1), 1994, pp 99-108. Limit depth theories are often used for settlement computation to simplify computational diff%zulties. Elementary stress distribution assumptions refer to the final stress state while the sequential evolution of the stress and strain fields is neglected. In the age of PCs there is no reason to maintain old and oversimplified assumptions of this kind. The computational model presented follows the load increase sequence and describes the physical fact of the limit depth change. Field measurements prove the adequacy of this approach. (Author)
Dynamic properties
956144 The characteristics of rock fracture under simula&d tide force - labor8tory study on the tkeory of loading and unloading response ratio (in Chinese) Shi Xing-Jue, Xu He-Ming, Wan Yong-Zhong, Lu ZhenGang & Chen Xue-Zhong, Acta Geophysics Sinica, 37(5), 1994, pp 633-637. According to the theory of loading and unloading response ratio, P wave velocity is selected as the response parameter. In the laboratory, rock samples are loaded to instability or fracture under the common action of simulated tectonophysical and tide forces. The travel time or wave velocity is measured in the whole process. It is found that the value of the response ratio Y is near 1 as the rock system is stable, but Y is gradually increased to the maximum value 10 as the rock approaches instability. The experimental result is very close to the ideal curve predicted by the theory. (from English summary)
956145 Inbomogeneous plane waves and cylindrical waves in 8nisotropic 8nelastic media E. S. Krebes & L. H. T. Le. Journal of Geophysical Research, 99(Bl2), 1994, pp 23,899-23,919. In isotropic anelastic media, the phase velocity of an inhomogeneous plane body wave, which is a function of Q and the degree of inhomogeneity 7, is significantly less than the corresponding homogeneous wave phase velocity typically only if 7 is very large (unless Q is unusually low). This study investigates inhomogeneous waves in anisotropic anelastic media, where phase velocities are also functions of the direction of phase propagation 0, and finds that: 1) the low phase velocities can occur at values of 7 which are substantially less than the isotropic values and that they occur over a limited range of oblique directions 0, and 2) for large positive values of y, there are ranges of oblique directions 8 in which the inhomogeneous waves cannot propagate at all because there is no physically acceptable solution to the dispersion relation. (from Authors)
Compression, swelling and consolidation 956140 Energy anply& of fdte element soil stress prediction W. A. Block, C. E. Johnson, A. C. Bailey, E. C. Burt & R. L. Raper, Transactions - American Society of Agricultural Engineers, 37(6), 1994, pp 1757-1762. Soil stresses under a rigid wheel loading were predicted with a finite element model using each of three different soil compaction models as the constitutive relationship. An energy analysis compared the energy lost in traction to energy absorbed in compaction as predicted by the finite element model. One constitutive relationship resulted in underprediction of energy absorbed in compaction while the other two resulted in overprediction. The method of energy analysis is shown to be a useful tool for evaluating accuracy of soil stress and strain predictions by a finite element model. (Authors) 956141 Soil stress measmrement under rigid wheel loading W. A. Block, C. E. Johnson, A. C. Bailey, E. C. Burt & R. L. Raper, Transactions - American Society of Agricultural Engineers, 37(6), 1994, pp 1753-1756. Understanding soil response to compactive forces may help in deciding how to manage the adverse effects such as soil erosion. Soil stress states were measured beneath the path of a rigid wheel. A multivariate analysis of variance was conducted on the data to determine the effect on stress state caused by dynamic and tractive wheel loads, in different soil types and with or without the presence of a hardpan. (from Authors) 956142 Boundary element analysis of stresses in an axisymmetric soil mass undergoing consolidation M. B. Chopra & G. F. Dargush, International Journal for Numerical & Analytical Methods in Geomechanics, 19(3), 1995, pp 195-218. A time domain boundary element method (BEM) for evaluating stresses in an axisymmetric soil mass undergoing consolidation has been developed. Previous BEM work is extended to permit the computation of stresses at both boundary and interior points. The stress formulation pre.serves the surface-only discretization. The boundary displa-
269A
cement integral equation is progressively differentiated to obtain the related stress and strain integral equations. Explicit expressions for the steady-state axisymmetric fundamental solutions are derived in this process. The transient components of the integrands are obtained directly from the transformation of the three-dimensional kernels into a cylindrical system. Numerical implication is carried out within a general purpose BEM computer code and examples are presented to validate the method. (Authors)
956143 Settlement analysis by the ‘moving Iimit depth’ model P. Scharle, Periodica Polytechnica: Civil Engineering, 38( 1), 1994, pp 99-108. Limit depth theories are often used for settlement computation to simplify computational diff%zulties. Elementary stress distribution assumptions refer to the final stress state while the sequential evolution of the stress and strain fields is neglected. In the age of PCs there is no reason to maintain old and oversimplified assumptions of this kind. The computational model presented follows the load increase sequence and describes the physical fact of the limit depth change. Field measurements prove the adequacy of this approach. (Author)
Dynamic properties
956144 The characteristics of rock fracture under simula&d tide force - labor8tory study on the tkeory of loading and unloading response ratio (in Chinese) Shi Xing-Jue, Xu He-Ming, Wan Yong-Zhong, Lu ZhenGang & Chen Xue-Zhong, Acta Geophysics Sinica, 37(5), 1994, pp 633-637. According to the theory of loading and unloading response ratio, P wave velocity is selected as the response parameter. In the laboratory, rock samples are loaded to instability or fracture under the common action of simulated tectonophysical and tide forces. The travel time or wave velocity is measured in the whole process. It is found that the value of the response ratio Y is near 1 as the rock system is stable, but Y is gradually increased to the maximum value 10 as the rock approaches instability. The experimental result is very close to the ideal curve predicted by the theory. (from English summary)
956145 Inbomogeneous plane waves and cylindrical waves in 8nisotropic 8nelastic media E. S. Krebes & L. H. T. Le. Journal of Geophysical Research, 99(Bl2), 1994, pp 23,899-23,919. In isotropic anelastic media, the phase velocity of an inhomogeneous plane body wave, which is a function of Q and the degree of inhomogeneity 7, is significantly less than the corresponding homogeneous wave phase velocity typically only if 7 is very large (unless Q is unusually low). This study investigates inhomogeneous waves in anisotropic anelastic media, where phase velocities are also functions of the direction of phase propagation 0, and finds that: 1) the low phase velocities can occur at values of 7 which are substantially less than the isotropic values and that they occur over a limited range of oblique directions 0, and 2) for large positive values of y, there are ranges of oblique directions 8 in which the inhomogeneous waves cannot propagate at all because there is no physically acceptable solution to the dispersion relation. (from Authors)