缝水压力和裂缝面接触条件对重力坝裂缝扩展影响

基于多边形比例边界有限元模拟了重力坝裂缝扩展过程,综合考虑了坝-库水-地基相互作用、裂缝面接触和缝水压力的影响。其中该接触模型能够有效防止裂缝面的相互嵌入;该缝水模型除能考虑裂缝面开合速度、缝隙宽度和水流形态对缝水压力分布的影响,还可基于连续性条件模拟缝内水体流动和空化的现象。以Koyna坝裂缝扩展为例,研究了裂缝面接触条件和缝水压力对计算结果的影响。结果显示,考虑接触的影响,震损较为严重。而与假定为常水压力分布的情况相比,实际的缝水压力分布形式对结果影响较为复杂。在裂缝张开时,减小了裂缝扩展的可能,而在裂缝闭合时正好与之相反。

Effects of in-crack water pressure and contact condition of crack surface on crack propagation in gravity dams

The polygon scaled boundary finite element method (polygon SBFEM) is used to simulate the crack propagation process of a gravity dam,including the effects of dam-reservoir-foundation interaction,contact condition of crack surfaces and in-crack water pressure.The contact model can prevent penetration of crack surface effectively.Concerning the distribution of in-crack water pressure,the aperture of the assumed rigid crack wall,the opening/closing velocity and the fluid state,i.e.,laminar flow or turbulent flow are considered.Furthermore,the cavitation and flow of the in-crack water are simulated based on the condition of continuity.The crack propagation process of the Koyna dam is analyzed to investigate the effects of contact condition of crack surface and in-crack water pressure.According to the results,the damage is increased when the contact condition is considered.Compared with the case of constant water pressure,the real distribution of water pressure has complicated influence on the results.When the crack is opening,the possibility of crack propagation is decreased,or,conversely,the possibility of crack propagation is increased,when the crack is closing.