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1.
A stress–strain relationship within porous rock under anisotropic stress conditions is required for modeling coupled hydromechanical
processes associated with a number of practical applications. In this study, a three-dimensional stress–strain relationship
is proposed for porous rock under elastic and anisotropic stress conditions. This relationship is a macroscopic-scale approximation
that uses a natural-strain-based Hooke’s law to describe deformation within a fraction of pores and an engineering-strain-based
Hooke’s law to describe deformation within the other part. This new relationship is evaluated using data from a number of
uniaxial and triaxial tests published in the literature. Based on this new stress–strain relationship, we also develop constitutive
relationships among stress, strain, and related stress-dependent hydraulic/mechanical properties (such as compressibility,
shear modulus, and porosity). These relationships are demonstrated to be consistent with experimental observations. 相似文献
2.
Summary A micromechanics-based model, able to quantify the effect of various parameters on the complete stress–strain relationship,
is described. The closed-form explicit expression for the complete stress–strain relationship of a rock material containing
an echelon cracks arrangement subjected to compressive loading is obtained. The complete stress–strain relationship including
the stages of linear elasticity, non-linear hardening and strain softening is established. The results show that the complete
stress–strain relationship and the strength of rock with echelon cracks depend on the crack interface friction coefficient,
the sliding crack spacing, the perpendicular distance between the two adjacent rows, the fracture toughness of rock material
and orientation of the cracks. The present model is used to evaluate the complete stress–strain relationship and strength
for crack-weakened rock at the underground cavern complex of the Ertan Hydroelectric Project. The predicted strength is in
agreement with that obtained by the Hoek–Brown criterion. The numerical results obtained with the complete stress–strain relationship
seem to be in good agreement with the measured values.
Author’s address: Xiao-Ping Zhou, School of Civil Engineering, Chongqing University, 443002 Chongqing, P.R. China 相似文献
3.
This study focuses on the stress and displacement of a circular opening that is excavated in a strain-softening rock mass incorporating the effects of hydraulic–mechanical coupling and rockbolts effectiveness. It follows the generalized Hoek–Brown failure criterion. Moreover, an improved numerical approach and stepwise procedure are proposed. This approach considers the deterioration of the strength, deformation, and dilation angle and the variation of elastic strain in the plastic region considering the effect of the hydraulic–mechanical coupling and the rockbolts effectiveness. The presented solutions were validated by FLAC results. Several examples are conducted to demonstrate the validity and accuracy of the proposed solution through MATLAB programming. Parametric studies are also conducted to highlight the influences of hydraulic–mechanical coupling and rockbolts effectiveness on stress and displacement. Results show that stress and displacement, incorporating the effects of hydraulic–mechanical coupling and rockbolts effectiveness, are between those when hydraulic–mechanical coupling or rockbolts effectiveness is considered separately. However, this theory needs more verification from practical engineering. 相似文献
4.
Lin-jian Ma Xin-yu Liu Qin Fang Hong-fa Xu Hui-min Xia Er-bing Li Shi-gang Yang Wen-pei Li 《Rock Mechanics and Rock Engineering》2013,46(1):53-66
According to the requirement of the West–East Gas Transmission Project in China, the solution-mined cavities located in the Jintan bedded salt formation of Jiangsu province will be utilized for natural gas storage. This task is more challenging than conventional salt dome cavern construction and operation due to the heterogeneous bedding layers of the bedded salt formation. A three-dimensional creep damage constitutive model combined with the generalized Hoek–Brown model is exclusively formulated and validated with a series of strength and creep tests for the bedded rock salt. The viscoplastic model, which takes the coupled creep damage and the failure behavior under various stress states into account, enables both the three creep phases and the deformation induced by vicious damage and plastic flow to be calculated. A further geomechanical analysis of the rapid gas withdrawal for the thin-bedded salt cavern was performed by implementing the proposed model in the finite difference software FLAC3D. The volume convergence, the damage and failure propagation of the cavern, as well as the strain rate of the salt around the cavern, were evaluated and discussed in detail. Finally, based on the simulation study, a 7-MPa minimum internal pressure is suggested to ensure the structural stability of the Jintan bedded salt cavern. The results obtained from these investigations provide the necessary input for the design and construction of the cavern project. 相似文献
5.
Xun Wu 《国际地质力学数值与分析法杂志》2020,44(17):2388-2392
6.
A. F. Redkin V. I. Velichkin A. P. Aleshin G. P. Borodulin 《Geology of Ore Deposits》2009,51(4):290-304
The experimental study of an F-bearing silicic melt—U, Nb, Ta minerals—chloride-fluoride fluid system is focused on ascertaining
the origin of uranium deposits spatially related to intraplate silicic volcanism. The first series of experiments on uranium
solubility in silicic melts close in composition to ore-bearing rhyolite of the unique Strel’tsovka Mo-U ore field has been
performed in order to determine more precisely the ore genesis. As starting solid phases, model homogeneous glass of the chemical
composition (wt %) 72.18 SiO2, 12.19 Al2O3, 1.02 FeO, 0.20 MgO, 0.33 CaO, 4.78 Na2O, 3.82 K2O, 1.44 Li2O, and 2.4 F (LiF, NaF, KF, CaF2, MgF2); synthetic UO2 and UO3·0.33H2O; and natural columbite were used. The starting solutions contained 1.0 m Cl and 10−2
m F. The runs were conducted in a gas vessel at a pressure of 1000 bar and in a high-pressure hydrothermal vessel at 2000 bar.
The O2 (H2) fugacity was set by Ni-NiO, Co-CoO, Fe3O4-Fe2O3, and Cu-Cu2O buffers. The equilibrium between melt and solution for major elements is reached during the first day, whereas 5–7 days
are required for ore elements (U, Nb, Ta) to come into equilibrium. The solubility of Nb and especially Ta in Cl-F solutions
equilibrated with F-bearing melt is extremely low. The solubility of U is much higher (10−4−10−5 mol/kg H2O). The energy dispersive spectroscopy of run products allowed us to establish that columbite dissolved incongruently with
formation of U- and F-bearing pyrochlores. The performed experiments have shown that a silicic melt close to the rhyolitic
magma of the Strel’tsovka caldera in composition is not able to generate postmagmatic ore-forming solutions containing more
than 10−6−10−5 mol U/kg H2O under the relatively low pressure necessary for the existence of the first type of fluid. The amount of uranium that could
have precipitated from this fluid in the zone of ore deposition is estimated at 216–9000 t. This estimate is two orders of
magnitude lower than the total uranium resources of the deposits localized in the Strel’tsovka caldera. Thus, the upper crustal
silicic magma chamber hardly was a source of uranium for Mo-U deposits of the Strel’tsovka ore field. 相似文献