隧道石膏质围岩水分传输与劣化机制研究

This study is focused on anhydrock from theoretical and experimental aspects. For simulating the erosion and deterioration on anhydrock by seasonal groundwater, some research work is carried out. Firstly, (capillary) water absorption test and penetration test of anhydrock in the dry/wet cycling condition are carried out while the time effect of water absorption and permeability of anhydrock and its influencing factors are analyzed. Secondly, by using the rock thin section and some technology such as scanning electronic microscope (SEM) and Mercury injection experiment, the rock pore is observed and analyzed. Then, by extracting characteristic parameters of rock pore, a simplified pore structure model is established on the basis of Sphere-capillary model to simulate the moisture transport in the anhydrock. Thirdly, by defining the rock damage variables with water absorption in the process of water transport, the relationship between the number of dry-wet process and the rock damage variables is analyzed. In addition, the relationship between strain and modulus of elasticity in the process of rock deformation is discussed according to the triaxial test results of anhydrock. Then, a coupling damage mechanics model with parameters of the number of dry-wet process and the rock damage variables is obtained by using the intermediate variable which is porosity. Finally, with the results of penetration-stress coupled experiment and triaxial test with different initial damage degree of anhydrock and rock physical model, the moisture transport and deterioration mechanism of anhydrock is analyzed.

以隧道工况下石膏质岩石为研究对象，从试验和理论两方面开展研究。为模拟季节性地下水对围岩的侵蚀、劣化作用，开展干湿循环条件下岩石（毛细）吸水和渗透试验，分析岩石吸水率与渗透率的时间效应及影响因素；采用薄片、扫描电镜、压汞试验等技术，观察、分析岩石孔（空）隙，根据孔隙照片提取孔隙特征参数，以球管模型为基础建立简化的孔隙结构模型，模拟岩石内水分传输特性。以水分传输过程中吸水率为岩石损伤变量，分析干湿循环次数与岩石损伤变量的关系。开展干湿循环条件下岩石三轴试验，讨论岩石变形过程中应变与弹性模量的关系。通过中间变量孔隙率，推导包含干湿循环次数、弹性模量的耦合损伤力学模型。结合岩石的渗透-应力耦合试验（虚拟围岩实际工况）与不同初始损伤度的三轴试验结果，同时借助岩石物理模型，系统分析隧道石膏质围岩水分传输与劣化机制。

在隧道建设过程中，原岩体的应力状态发生改变，围岩次生裂隙的产生为地下水提供了通道，在降水补给地下水区域，岩石会遭到干湿交替式的侵蚀，损伤逐步累积，从而使得岩石劣化，隧道的正常施工、运营常常受到影响，因此，有必要开展隧道石膏质围岩水分传输与劣化机制方面的研究，为工程建设提供理论支撑。本项目以隧道工况下石膏质岩石为研究对象，从试验和理论两方面开展研究。为模拟季节性地下水对围岩的侵蚀、劣化作用，开展干湿循环条件下岩石（毛细）吸水和渗透试验，分析岩石吸水率与渗透率的时间效应及影响因素；采用薄片、扫描电镜、压汞试验等技术，观察、分析岩石孔（空）隙，根据孔隙照片提取孔隙特征参数，进行分析研究。以水分传输过程中吸水率为岩石损伤变量，分析干湿循环次数与岩石损伤变量的关系。开展干湿循环条件下岩石单轴和三轴试验，讨论岩石变形过程中应变与弹性模量的关系。本项目通过宏观与微观、试验与理论相结合的研究手段、方法，探讨了石膏质岩干湿循环下水分传输规律及干湿循环和荷载共同作用下岩石的损伤模型，揭示隧道石膏质围岩水分传输及劣化机制，为此类问题的研究提供新思路、新途径。