深部岩体多处于复杂应力场和渗流场中,研究围压和渗透压作用下黏土岩特性对高放射性废物深地质处置库的设计开挖具有重要的意义。通过塔木素黏土岩围压加卸载渗透率演化试验及不同围压和渗透压下全应力-应变渗透率试验,分析了其渗透和强度特性。综合考虑围压和渗透压对黏土岩强度的影响,引入围压强化系数和渗透压弱化系数,并结合不同强度准则在表征黏土岩强度特性中的适用性对比,提出一种考虑围压和渗透压共同作用的黏土岩强度准则。研究结果表明:塔木素深部黏土岩渗透率均处于10-20 m2数量级,其渗透率与围压的关系在加载阶段满足指数函数关系,在卸载阶段满足幂函数关系;全应力-应变过程中,黏土岩围压强化系数大于渗透压弱化系数,共同作用时,围压对黏土岩强度的影响占主导。考虑围压和渗透压共同作用的强度准则能更好地反映塔木素黏土岩的强度特性,克服了Mohr-Coulomb和Hoek-Brown强度准则仅考虑围压变化的局限。
Abstract
Deep rock mass is mostly in complex stress field and seepage field. Studying the characteristics of clay rock under confining pressure and osmotic pressure is of great significance for the design and excavation of highly radioactive waste repository. In this paper, we examined the strength and permeability of Tamusu clay via permeability evolution test under loading-unloading confining pressure and full stress-strain permeability test under different confining pressures and osmotic pressures. Having compared the applicability of different strength criteria in characterizing the strength characteristics of clay, we proposed a strength criterion for clay rock in consideration of confining pressure and osmotic pressure by introducing a strengthening coefficient of confining pressure and a weakening coefficient of osmotic pressure. Results demonstrate that the permeability of Tamusu deep clay is in the order of 10-20 m2, and the relationship between permeability and confining pressure conforms to exponential function in loading stage while power function in unloading stage. In the whole stress-strain process, the strengthening coefficient of confining pressure is greater than the weakening coefficient of osmotic pressure. When working together, confining pressure has a dominant influence on the strength of Tamusu clay. The strength criterion considering the interaction of confining pressure and osmotic pressure could better reflect the strength characteristics of the Tamusu clay rock and overcome the limits of Mohr-Coulomb and Hoek-Brown strength criterion which only consider the confining pressure variation.
关键词
黏土岩 /
渗透压 /
渗透性 /
强度准则 /
围压强化系数 /
渗透压弱化系数 /
塔木素
Key words
clay rock /
osmotic pressure /
permeability /
strength criterion /
strengthening coefficient of confining pressure /
weakening coefficient of osmotic pressure /
Tamusu
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基金
国家国防科技工业局项目(科工二司[2014]1587号);国家自然科学基金项目(51869002);东华理工大学研究生创新项目(DHYC-201813)
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