基于数值流形法的重力坝水力劈裂研究

运用数值流形法在非连续介质领域的独特优势，并结合断裂力学的基本原理，分析了重力坝的水力劈裂破坏问题，实现了重力坝起裂、扩展和渐进破坏的全过程。充分发挥应力强度因子判别法和带抗拉强度的摩尔-库仑破坏准则各自的优势，根据不同情况选取其中某种方法确定断裂和扩展方向，且不需要预制初始裂纹。选取一个算例两种工况分析了重力坝在不考虑裂纹面内水压力和考虑裂纹面内水压力的水力劈裂破坏情况。计算结果表明，在重力坝的水力劈裂中，当不考虑裂纹面内水压力时，坝踵处裂纹向下游和深部扩展，上游折坡点处裂纹属于压剪型破坏；当考虑裂纹面内水压力时，坝踵处裂纹偏向深度方向扩展，折坡点处的裂纹逐渐由压剪破坏变成了拉剪破坏，并且考虑裂纹面内水压力后坝体破坏所需要的时步减少，故而考虑裂纹面内水后降低了重力坝的安全系数。该方法加深了对重力坝水力劈裂破坏的认识，具有较大的实际应用价值。

Study on hydraulic fracture of gravity dam using the numerical manifold method

The hydraulic fracture of the gravity dam was analysed by considering the advantages of the numerical manifold method in the non-continuum field and the basic principle of fracture mechanics. Besides, this study realised the whole process of dam crack initiation, propagation and progressive failure. With the respective advantages of the Mohr-Coulomb failure criterion with tensile strength and the stress intensity factor discriminant criterion, the fracture and its propagating direction were determined according to different conditions, and no pre-notched model was required. One example under two different conditions was selected to analyse the hydraulic fracture of the gravity dam with or without considering the inner water pressure on crack. The results showed that for the hydraulic fracture of gravity dam without considering inner water pressure on crack, the crack of dam site propagated toward the direction of downstream and depth, and the crack propagation at the upstream slope belonged to the compression-shear failure. However, when considering the inner water pressure on crack, the crack of the dam site was extended in the direction of depth, and the crack propagation of slope point belonged to the tension-shear failure. Furthermore, the required time steps for the dam failure were reduced, resulting in the decrease of the safety factor of the dam. This study has deepened the understanding of hydraulic fracture of the gravity dam and has great practical application value.