裂缝影响下碾压混凝土拱坝整体安全度评价

摘要

以某碾压混凝土双曲拱坝为例,采用薄层单元模拟该坝拱冠梁处径向贯穿性裂缝,建立三维有限元仿真模型并进行非线性分析,研究有无裂缝2种情况下坝体的变位和应力状态,以及超载情况下拱坝-地基系统各部位的屈服情况,综合评价裂缝对该拱坝整体安全度的影响.研究结果表明:各计算工况下,裂缝对坝体应力和位移的整体分布规律影响较小,2种模型下坝体的应力场和位移场基本相同,但有缝时裂缝端部附近会出现较为明显的应力集中现象,应采取加固措施以防止裂缝进一步扩展；超载时,2种模型下拱坝-地基系统各部位的屈服情况基本相同,坝体材料按照线弹性分析时,2种模型超载整体安全度均为6.0左右,按照弹塑性分析时,整体安全度均为4.0左右.该拱坝径向贯穿性裂缝对拱坝-地基系统整体安全度无显著影响.%Using the model of thin layer element to simulate the radial penetrating cracks of an RCC arch dam, two 3-D with and without cracking FEM models were established according to the geological and mechanical characteristics. Based on the results of nonlinear analysis, according to the distribution of stress and displacement and the yield distribution of dam and foundation when overloading, the influence of crack on the global safety degree of dam-foundation system was evaluated. The research results demonstrate that the calculating results of two different models are almost the same in all conditions. Crack has little influence on the distribution of stress and displacement, but stress concentration occurs at the end of the crack in cracking model, so measures should be taken to prevent the crack from developing. Under overloading, the yield distributions of dam-foundation system of two different models are also similar, the global safety degrees of two models are both 6.0 with elastic dam materials, and 4.0 with elastic-plastic dam materials. The radial penetrating cracks have little influence on the global safety degree of this dam.