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。

As more and more high-dam hydropower and high head pumped storage projects have been constructed in China, the rock foundation of high dam and high pressure water diversion system generally sustain high water pressure and hydraulic gradient. In this circumstance, not only nonlinear flow is prone to occur in rock seepage; but also accompany with leakage, seepage failure and water-inrush risk. This study experimentally investigated the nonlinear flow characteristics of broken granite rock in Yangjiang subjected to a wide range of confining pressures (1-30 MPa) through triaxial cell test system. The characteristics of nonlinear flow in broken granite rock have been elucidated; and its representation methods have been investigated. The results show that nonlinear flow occurs in the broken granite with the increasing hydraulic gradient, while the flow nonlinearity decreases with the increasing confining pressures. Combined with the cracked morphology of broken granite and the magnitude of the permeability, three possible causes triggering the nonlinear flow have been elucidated, i.e. inertial effect, seepage failure and solid-water interaction. Further, the Forchheimer and Izbash equations have been adopted to characterize the nonlinear flow, respectively, which both provide excellent description for the nonlinear flow in broken granite. The nonlinear coefficient of Forchheimer equation experience positive and negative values during the loading process, which is possibly ascribed to the closure and extension of the cracks in the broken granite. The power-law function between the nonlinear coefficients of Izbash equation has been developed by relating them with confining pressures. The results may prove useful in proper understanding of fluid flow through fault zone and compressive zone under high water pressure and hydraulic gradient.