各向异性柱状节理岩体渗流应力耦合试验与力学模型研究

Columnar jointed rock shows significant anisotropy, which has become one of the key scientific and technical issues for design and construction of many large hydropower projects. In this study, based on the analysis of engineering geology characteristics and evolutionary character of columnar jointed rock, carried out true-triaxial testing of hydro-mechanics of blind joints sample and anisotropy similar material, according to coupling property analysis to reveal its anisotropic hydro-mechanics coupling mechanism and characteristics, establish the 3-D mechanical model of hydro-mechanics coupling, this model reflect the evolutional feature between stress strain- wave velocity-permeability of columnar jointed rock with anisotropic characteristic, carry out the research of numerical method and engineering application, based on the compare with isotropic mechanical model, obtain the influence law of the anisotropic mechanical property of columnar jointed rock on seepage behavior and stress strain behavior of rock mass.

柱状节理岩体力学基本特征为各向异性，开展各向异性柱状节理岩体渗流应力耦合试验和力学模型研究对岩石力学学科和水工工程建设具有重要的理论意义和实践价值。本项目在探求柱状节理岩体工程地质特性和演化特征基础上，进行含隐节理岩石和各向异性相似材料试样的渗流应力耦合真三轴力学试验，开展耦合特性分析，揭示各向异性柱状节理岩体渗流应力耦合机理，建立反映柱状节理岩体各向异性特征的应力应变-波速-渗透率演化规律及三维耦合力学模型，发展相应的数值计算方法，开展工程应用案例研究，比较各向同性力学模型分析成果，掌握柱状节理岩体各向异性力学特性对岩体渗流行为和应力变形的影响规律。

柱状节理岩体尺度跨度大，结构复杂，各向异性特性明显。基于柱状节理岩体工程地质和结构特性，采用相似材料制备反映柱状节理特征的相似材料试样。开展了不同柱体倾角柱状节理岩体渗流力学特性试验，研究了循环加卸载下柱状节理岩体渗透率随围压和柱体倾角的变化规律；开展了不同围压和渗压组合条件下的渗流应力耦合三轴力学试验，研究了柱状节理岩体在渗流作用下的力学特性和水力耦合下的渗透特性；基于微结构张量理论和弹塑性力学原理，推求柱状节理岩体渗透率张量的表达形式，在各向异性弹塑性模型的基础上，建立渗透压力对屈服函数的影响关系，结合渗流应力耦合作用下的各向异性渗透张量，建立各向异性渗流应力耦合力学模型；开发本构模型，开展工程应用研究，分析柱状节理岩体各向异性力学特性对岩体渗流力学行为和应力变形的影响规律。研究成果将有助于各向异性岩石渗流力学理论的发展，有助于掌握岩体各向异性对岩石工程安全性的影响。