随着我国高土石坝的建设，渗流引发的安全问题日益凸显。工程中观察到的许多难以解释的渗流现象是耦合作用的结果。与此同时，利用耦合机理实现渗流安全问题的监测和治理，是未来发展的趋势。本文通过单元试验、室内模型试验、数值模拟等多种方法，对细粒土中的应力应变、温度与渗流的耦合问题展开深入的研究。主要工作和成果如下：（1）改进了三轴剪切-渗透试验及接触面剪切-渗流试验的装置和方法，开展系列试验研究了多种细粒土及接触面剪切过程中渗透特性的变化规律。试验结果表明：细粒土在剪切作用下的渗流特性受剪切变形的影响显著；以应力水平为变量的渗透系数数学模型的局限性，需要建立新的模型；土体与混凝土接触面发生相对错动时，土体接触面的渗透性之间降低并趋于稳定。（2）研制了多功能岩土模型箱，开展了系列试验研究渗流和温度的耦合规律。试验结果表明：在渗流作用下，温度场的变化明显且具有规律性；渗流作用下的温度变化规律可以反映土层的渗透系数及渗流强度；孔压随温度升高而升高，且规律性良好。（3）利用电镜扫描试验对剪切-渗流耦合机理进行了深入研究，揭示了细粒土在剪切作用下的渗透特性变化的机理，提出了更具有普适性的剪切-渗流数学模型。通过有限元分析模拟接触面剪切-渗流试验，验证了剪切-渗流数学模型的正确性，并揭示了接触面剪切-渗流试验中试样内部应力应变、孔隙比和渗透系数的演化过程。分析温度-渗流室内模型试验，提出了具有工程实用性的多因素耦合导热系数模型及温度-孔压模型。（4）在考虑了土石坝工程特点的简化理论的基础上，引入温度的影响，建立了考虑应力变形-温度-渗流耦合的分析方法。所建立的分析方法充分考虑土体的物理状态、应力应变、渗流和温度之间的相互影响，并充分结合机理研究成果及岩土工程的特点。使用伽辽金方法推导了此分析方法的有限元格式，开发了相应的计算程序。引入欠松弛方法和预处理方法，提高了方程求解的精度、效率和稳定性。对经典一维算例、室内模型试验和泸定水电站下游河道的实际工程算例进行模拟，计算结果与试验结果、现场测试结果符合较好，验证了理论和方法的可靠性和实用性。
With the construction of high earth-rock dams in China, the safety issues caused by seepage have become increasingly prominent. Many abnormal seepage phenomena are the consequence of multi-factor coupling. Meanwhile using the coupling mechanisms to improve the monitor and management of seepage safety issues is the trend of future development. In this dissertation, an intensive study was conducted regarding the stain-stress-temperature-seepage coupling problem in fine-grained soil by means of shear-seepage test, indoor model test, and numerical simulation. The main work and contributions of this dissertation are as follows:(1) Based on the improved triaxial shear-seepage apparatus and contact-shear-seepage apparatus, a series of tests were conducted to study the seepage characteristics of both the fine-grained soil and the contact interface under shear. Results showed that the seepage characteristics of fine-grained soil are significantly affected by shear deformation, indicating the limitation of the previous mathematical model. The permeability of contact surface tends to decrease and then be stabilized when the shear displacement between the concrete contact surface and the soil develops.(2) A series of indoor temperature-seepage model tests were carried out using a newly developed multifunctional geotechnical model box to study the coupling mechanism between seepage and temperature. Results show that the change of temperature field under seepage is obvious and regular; the change of temperature under seepage can reflect the hydraulic conductivity and the seepage intensity inside the soil layer. Moreover, the pore water pressure rises with increasing temperature with good regularity.(3) An in-depth study was carried out by using the scanning electron microscope and revealed the seepage mechanism of find-grained soil under shear. A more general shear-seepage mathematical model was proposed. The finite element analysis was then performed to simulate the contact-shear-seepage test, which verifies the model’s validity and reveals the evolution of the stress-strain state, void ratio and hydraulic conductivity during shear. A coupled thermal conductivity model and a temperature-pore pressure model were proposed based on the indoor temperature-seepage model tests.(4) A multi-factor coupling analysis method that considers the coupling of stress-strain state, temperature, seepage, the results of mechanism research, and the characteristics of geotechnical engineering was proposed based on a simplified consolidation theory for unsaturated soil. The finite element format of the method was derived using the Galerkin method, and the corresponding calculation code was developed. The introduction of the under-relaxation method and the preprocessing method improved the accuracy, efficiency and stability of the equation solving. The code was verified by three different cases, including the classic one-dimensional case, the indoor model test case, and the engineering case of the downstream river course of the Luding Hydropower Station. The calculation results are in good agreement with the test results in laboratory and in field, which verifies the reliability and practicability of the theory and method.
