论文部分内容阅读
随着我国高坝枢纽工程和高水头抽水蓄能电站的大规模兴建,高坝岩基和高压引水系统围岩将承受极高的渗透水压和水力坡降,不仅导致岩体渗流产生强烈的非线性,而且导致岩体发生渗漏、突透水和渗透破坏的风险急剧增大。采用Triaxial Cell三轴试验系统,开展不同围压(1~30 MPa)下阳江破碎花岗岩的非线性渗流试验,研究高水力梯度条件下破碎花岗岩的非线性渗流特性及其表征方法。试验结果表明,随着水力梯度的逐步增大,破碎花岗岩中的水力梯度与渗流流量呈非线性特征;在围压加载过程中破碎花岗岩的非线性渗流特征逐渐减弱。结合花岗岩的破碎形态和渗透率量级,提出了破碎花岗岩非线性渗流3种可能的成因机制即惯性效应、渗透失稳和固液界面效应。在该基础上分别采用二次函数型Forchheimer公式和幂函数型Izbash公式对试验结果进行拟合,结果表明二者均能很好地表征破碎花岗岩的非线性渗流行为。Forchheimer公式非线性系数既能够表征渗流的惯性效应,又能表征渗透失稳机制,其在量值上随着围压的增大呈现正负交替现象,与围压加载过程中破碎花岗岩裂纹的闭合和扩展密切相关;Izbash公式非线性系数则既能够表征渗流的惯性效应,又能表征低渗介质非线性渗流的固液界面效应,其在量值上与围压存在相关性很好的幂函数关系。研究成果对于深化高渗压、大水力梯度条件下断层破碎带和挤压带非线性渗流规律研究具有重要意义。
With the large-scale construction of the dam high dam project and high-head pumped storage power station in China, the surrounding rock of the high rock embankment and the high-pressure water diversion system will withstand extremely high infiltration hydraulic pressure and hydraulic gradient, which will not only lead to the intense Nonlinear, but also lead to leakage of rock mass, sudden penetration of water and penetration of the risk of sharp increase. The non-linear seepage test of the Yangjiang fractured granite under different confining pressures (1 ~ 30 MPa) was carried out by Triaxial Cell triaxial test system to study the nonlinear seepage characteristics and the characterization of the fractured granite under the condition of high hydraulic gradient. The experimental results show that with the increase of hydraulic gradient, the hydraulic gradient and the seepage flow rate in the fractured granite are nonlinear. The nonlinear seepage characteristics of the fractured granite gradually decrease during the confining pressure loading. According to the crushing morphology and permeability of granite, three possible genetic mechanisms of non-linear percolation of crushed granite are proposed: inertial effect, seepage instability and solid-liquid interface effect. Based on these results, the quadratic function Forchheimer formula and the power function Izbash formula were used to fit the experimental results respectively. The results show that both of them can well characterize the nonlinear seepage behavior of the fractured granite. Forchheimer formula nonlinear coefficient can not only characterize the inertia effect of seepage but also characterize the mechanism of seepage failure, which shows positive and negative alternations with the increase of confining pressure in magnitude, which is close to the closure of the fractured granite during confining pressure loading Which is closely related to the expansion. The nonlinear coefficient of the Izbash formula can not only characterize the inertial effect of seepage but also characterize the solid-liquid interface effect of the nonlinear seepage in the hypotonic medium, which has a good power function relationship. The research results are of great significance for deepening the study of nonlinear seepage law of fault fracture zone and compression zone under the conditions of high seepage pressure and large hydraulic gradient.