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刘雪莹, 俞缙, 周先齐, 姚玮, 任崇鸿, 蔡燕燕. 一种岩石各向异性蠕变-渗透率模型[J]. 岩土工程学报. DOI: 10.11779/CJGE20240449
引用本文: 刘雪莹, 俞缙, 周先齐, 姚玮, 任崇鸿, 蔡燕燕. 一种岩石各向异性蠕变-渗透率模型[J]. 岩土工程学报. DOI: 10.11779/CJGE20240449
An anisotropic creep-permeability model for rock[J]. Chinese Journal of Geotechnical Engineering. DOI: 10.11779/CJGE20240449
Citation: An anisotropic creep-permeability model for rock[J]. Chinese Journal of Geotechnical Engineering. DOI: 10.11779/CJGE20240449

一种岩石各向异性蠕变-渗透率模型

An anisotropic creep-permeability model for rock

  • 摘要: 地下工程服役期较长,富水环境下围岩蠕变变形加剧,三向应力下围岩渗透性呈各向异性变化,为了描述围岩蠕变过程中渗透率各向异性变化,将岩石简化为立方体模型,结合蠕变曲线特征分阶段建立岩石蠕变-渗透率模型。黏弹性阶段定义裂隙与岩石的黏滞系数比、引入侧向影响系数表示侧向应力对裂隙开度影响,黏塑性阶段引入表示裂隙对渗流通道影响的修正系数,结合岩石各向异性蠕变模型、立方定律、含裂隙岩石渗透率方程,建立岩石各向异性蠕变-渗透率模型。利用真三轴条件下蠕变-渗流试验结果对各向异性蠕变-渗透率模型进行验证,模拟了不同条件下渗透率演化。结果表明:与传统Kozeny- Carman(K-C)模型以及已有各向异性蠕变-渗透率模型相比,本文提出的各向异性蠕变-渗透率模型精度更高,可以描述黏弹性阶段渗透率因岩石孔裂隙逐渐被压密而逐渐降低、加速蠕变阶段渗透率在裂隙逐渐汇聚影响下突增的变化趋势。对各向异性蠕变-渗透率模型参数进行了敏感性分析,随着裂隙与岩石的黏滞系数比增加,渗透率衰减越快,渗透率稳定值越低,随着黏弹性阶段侧向影响系数越高渗透率初始衰减速率越高,渗透率稳定值越低;黏塑性阶段修正系数越高,加速蠕变阶段渗透率开始大幅增加。

     

    Abstract: The service life of underground engineering is long, and the creep deformation of surrounding rock can be intensified in the water environment and the permeability shows a dynamic anisotropic trend. In order to describe the dynamic anisotropy variation of rock permeability, the rock is simplified as a cube model, a rock creep permeability model is established in stages based on creep characteristics. In the viscoelastic stage, the ratio of viscosity coefficient between cracks and rocks is defined, and a lateral influence coefficient is introduced to represent the influence of lateral stress on crack opening. In the viscoplastic stage, a correction coefficient is defined to represent the influence of cracks on seepage channels. an anisotropic creep-permeability model is established combined with anisotropic creep damage model for rock, cubic law, and the permeability model for fractured rock. The creep-seepage tests under true triaxial conditions are performed, and the anisotropic creep-permeability model is validated. The model parameters can be determined and dynamic evolution of permeability under different conditions is analyzed. The present model shows the higher accuracy compared with the traditional K-C model and the previously anisotropic creep-permeability model. It can be used to describe the trend that the permeability decreases due to the gradual compaction of pores and cracks in the viscoelastic stage, and it increases suddenly caused by the gradual convergence of cracks in the accelerated creep stage. Sensitivity analysis has been conducted on the parameters in the anisotropic creep-permeability model. As the viscosity coefficient ratio increases, the permeability decays fast and the stable permeability decreases. As the viscosity coefficient increases, the initial decay rate of permeability increases, and the stable permeability decreases. In the accelerated creep stage, As the correction coefficient increase, the permeability begins to increase significantly.

     

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