Numerical investigation on crack propagation process of concrete gravity dams under static and dynamic loads with in-crack reservoir pressure

Abstract

Proper consideration of external and internal loads acting on concrete gravity dams is of vital importance in concrete dam engineering, since it plays a significant role in the stability assessment of cracked dams under static/dynamic conditions. Several factors which may affect the mechanical response of concrete gravity dams, however, have not been comprehensively accounted for in most previous crack propagation analyses. To adequately evaluate the crack propagation response of concrete gravity dams, a finite element-based numerical analysis is carried out to estimate the crack propagation in a concrete gravity dam under static and seismic loads. In this work, the effects of the water pressure inside the stress-free crack and the fracture process zone (FPZ), the cohesive force within the FPZ, the hydrostatic water pressure, and the dam-reservoir interaction are incorporated via a series of reasonable assumptions. On the basis of a stress intensity factor (SIF)-based mixed mode I-II crack propagation criterion, a generic numerical algorithm is proposed to estimate the crack growth process of concrete gravity dams under static and seismic loads. Application of this algorithm to two case studies of concrete gravity dams under different loading conditions demonstrates the validity of the algorithm in estimating the static and seismic crack propagation response. It is found that when a concrete gravity dam is subjected to static loading, crack initiation does not occur before the reservoir water level exceeds the dam height, and that the water pressure inside stress-free cracks has a slight negative effect on the structural resistance against cracking while the water pressure within the FPZ has no effect on the dam capacity. The seismic crack growth analysis indicates that the water pressure inside cracks causes the crack to propagate at a larger downward angle towards the downstream face with a larger crack growth length.