EXPERIMENTAL STUDY ON HYDRO-MECHANICAL COUPLING RELAXATION CHARACTERISTICS OF SATURATED SANDSTONE
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摘要: 岩石水-力耦合松弛特性是影响硐室围岩工程长期安全稳定的关键因素之一。采用岩石多场耦合三轴试验系统,对饱和灰砂岩在水力耦合条件下的有效围压规律及应力速率依存性开展应力松弛试验,并根据松弛特点选用三单元广义Maxwell松弛本构模型进行数值模拟验证。结果表明:1)水-力耦合条件下饱和砂岩具有非完全衰减松弛特性;2)相同有效围压条件下,无孔压试样的松弛程度略低于有孔压试样,而稳态松弛速率只有有孔压试样的45%左右;3)砂岩水-力耦合松弛具有显著的速率相关性,松弛程度和初始松弛速率均随加载速率升高而增大,最高加载速率试样的初始松弛速率几乎为最低加载速率试样的6倍,而稳态松弛速率没有明显差异;4)三单元广义Maxwell松弛本构模型能较为准确地描述砂岩水-力耦合松弛全过程。Abstract: The hydro-mechanical coupling relaxation characteristics is one of the key factors for long-term safety and stability of surrounding rocks. The hydro-mechanical coupling tests on effective confining pressure laws and sensitivity loading rates of saturated grey sandstone were conducted by the multi-field coupling triaxial test system. According to the relaxation characteristics, the generalized Maxwell relaxation constitutive model with three elements was adopted for the implementation of numerical verifications. The results showed that: 1) In the condition of hydro-mechanical coupling, saturated sandstone had the characteristics of incomplete attenuation relaxation. 2) Under the same effective confining pressure, the relaxation degrees of specimens without pore water pressure were slightly lower than that with pore pressure, while relaxation rates in the steady state were only about 45% of that with pore pressure. 3) The relaxation characteristics of sandstone depended significantly on loading rates. The relaxation degrees and initial relaxation rates increased with loading rates, in which the initial relaxation rates of specimens with the highest loading rate were almost six times rates for specimens with the lowest loading rate, while the relaxation rates in the stead state were no obvious different. 4) The whole process of hydro-mechanical coupling relaxation of sandstone could be accurately described by the three element generalized Maxwell relaxation constitutive model with three elements.
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Key words:
- sandstone /
- relaxation /
- rock rheology /
- hydro-mechanical coupling /
- relaxation constitutive model
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