CRACKING ANALYSIS OF ARCH DAMS BY 3D BOUNDARY-ELEMENT METHOD

A procedure is presented for the analysis of the stability and propaga tion of cracks in arch darns based on linear elastic fracture mechanic s and three-dimensional boundary element modeling. A simplified crack propagation criterion is employed and the crack trajectories are obtai ned by multistep extension. The first upstream cracking which occurred in the Kolnbrein arch dam is studied in detail under various conditio ns concerning the foundation interface, location of crack initiation, reservoir water level and load combinations. Crack trajectories close to the observed one are obtained with water level at 1,850-1,860 m, wh ich agrees with the prototype experience. It is found that the hydrost atic load and associated uplift pressure on the crack surfaces are the key factors for causing an initial crack at the dam base to propagate to the upstream face. It is also noted that the bonded condition at t he interface between the dam and the upstream elevated foundation is r esponsible for producing the distinctive profile of the observed crack , which daylights on the upstream face at an acute angle.