水分-应力耦合作用下软岩的流变机理及其扰动状态理论模型

With the continuous development of soft rock engineering constructions in water environment, long-term stability of soft rock engineering under the condition of water becomes increasingly prominent, so its rheological mechanism of moisture-mechanical coupling has quietly become one of the basic topics at the forefront of geotechnical engineering. Combining with the practical problems of large deformation of soft rock engineering disasters, qualitative and quantitative analysis for the microscopic structural changes in the soft rock during the creep process is taken firstly, in terms of the conventional compression performance tests、triaxial creep test and real-time CT scan. Based on the disturbed state concept and rheology theory, the soft rock creep damage process under the condition of water is effectively analyzed by integrating two angles of macro- and meso-. More importantly, rheology macro microscopic mechanism of soft rock and response law of the parameters considering moisture-mechanical coupling are further researched, and representation of relationship between disturbance factor and meso-structure evolution is researched too. On this basis, the coupled moisture-mechanical rheological model based on disturbed state concept is presented, and the model validity is tested by comparing the theoretical and experimental results after embedded into the FLAC3D. The studies will enrich the existing rock rheology theoretical system and provide new ideals and methods for carrying out the rheological mechanism of rock under the influence of many factors, and it will also provide a theoretical foundation and analytical tools to solve the security and stability problems of the soft rock engineering.

随着水环境下软岩工程建设的不断发展，软岩在含水状态下的长期变形与稳定性问题日趋突出，考虑水分-应力耦合作用的软岩流变机理研究已成为岩土工程界的基础性前沿课题之一。本课题拟结合软岩工程大变形灾害的实际问题，通过不同含水状态下软岩的常规抗压性能试验、三轴蠕变试验和实时CT扫描技术等手段，对软岩蠕变过程中的微观结构变化进行定性与定量分析；基于扰动状态理论和岩石非线性流变力学理论，从宏观和细观两个角度有效分析含水状态下软岩的时效变形破坏过程，重点研究水分-应力耦合作用下软岩流变的宏细观机理和参数的响应规律，以及扰动因子与细观结构演化的表征关系；构建基于扰动状态概念的软岩水分-应力耦合作用流变模型，并嵌入FLAC3D程序进行模型的有效性检验。课题研究将完善目前已有的岩石流变力学理论体系，为开展多因素影响下岩石的流变机理研究提供新的思路和方法，并为解决软岩工程的安全与稳定问题提供理论基础和分析手段。

随着水环境下软岩工程建设的不断发展，软岩在含水状态下的长期变形与稳定性问题日趋突出，考虑软岩的水稳定性及水-力耦合作用下软岩流变机理研究已成为岩土工程界的基础性前沿课题之一。本课题主要开展了以下方面研究：1）针对典型的红层软岩—泥质页岩进行了静态崩解试验及耐崩解试验，探讨了该类岩石在不同pH值溶液下的崩解特性及其变化规律，在此基础上基于能量耗散原理及分形相似性原理，针对pH值变化时岩样崩解的响应规律进行了深入分析并建立了相应的演化计算模型；2）利用RLW-2000岩石流变试验机对盐岩试件进行了三轴压缩分级加载蠕变试验，并基于非线性流变力学理论，提出了一种非线性黏滞体，将非线性黏滞体替换常规Burgers模型中的线性黏滞体，建立了可描述盐岩非线性蠕变特性的MBurgers模型，且结合试验进行了模型参数的反演；3）开展了软岩及其注浆体的室内流变试验特性试验，并基于扰动状态理论建立了软岩的流变力学本构模型，完成了其在复杂应力状态下的推广，实现了基于FLAC3D二次开发的模型程序化，并对石林隧道大变形段进行了数值模拟分析，确定了二次衬砌最佳支护时段，并结合工程实际提出了大变形段围岩变形的控制技术。研究成果为开展多因素耦合影响下岩石的流变行为研究提供了新的思路和方法，同时可将本课题提出的时效变形计算方法直接应用于类似软岩工程的安全与长期稳定评价，以及推广应用于软岩工程的设计和维护都有较为现实的经济和社会价值。