复杂地质条件下高拱坝整体稳定研究与软弱结构强度弱化效应影响分析

Research on High Arch Dam Overall Stability Under Complicated Geological Conditions and the Impact Analysis on Weakening Effect of Weak Structure Strength

锦屏一级高拱坝坝高库大,坝址区地质条件复杂,坝与地基整体稳定问题突出。工程蓄水运行后,坝肩结构面及软弱岩体的强度在高应力、强渗压的长期作用下将降低,对拱坝整体稳定更为不利。为评价加固后工程安全性,由水岩耦合三轴试验得到各软弱结构面强度在不同条件下的弱化率,并在此基础上采用综合法地质力学模型试验。由于试验技术限制,对结构面无法实现分区降低破碎带及影响带强度,综合各方面因素,模型试验最终采用破碎带统一降强30%的弱化方案。针对软弱结构面强度弱化效应对整体稳定的影响,采用3维非线性有限元软件对破碎带统一降强30%(方案1)和破碎带及影响带分区降强(方案2)进行计算分析;通过对比2种方案计算结果,正常工况下方案2坝体变位较方案1增加幅度约-0.2%~2.24%,坝肩变位值较方案1增加幅度约-2.35%~1.72%,超载工况下坝体变位增加幅度约-4.68%~9.23%。2种方案下坝体及坝肩抗力体变位、破坏过程及机理规律相似,量值相近,且试验与计算成果相近。综合分析认为,锦屏一级拱坝模型试验采用在破碎带统一降强30%来模拟破碎带及影响带分别降强合理可行,试验成果可靠。

In order to evaluate the engineering safety of Jinping I high arch dam after reinforcement,the weakening rates of the weak structure strength under different conditions were obtained by the water-rock coupling triaxial test. On this basis,the geological mechanics model test with synthetic method was conducted,in which the weakening scheme with an average weakening rate 30% of fracture zone was considered. In order to explore the influence of weakening effect of weak structural plane strength to overall stability,3D nonlinear finite element calculation and analysis were done for the fracture zone with an average weakening rate of 30%( Scheme 1) and the fracture zone with decreased and influenced strength( Scheme 2). The results showed that under normal operating conditions,displacement of the dam of scheme two is greater than scheme one about- 0. 2% ~ 2. 24%,abutment displacement value is greater than scheme one about- 2. 35% ~ 1. 72%,and displacement of the dam is greater than scheme one about- 4. 68% ~ 9. 23% under overload conditions.The displacement of dam and abutment resistance body,failure process and mechanism of the two schemes are similar,the numerical values are basically the same,and the test and calculation results are similar. For model test of Jinping I high arch dam,using the plan which concentrately reducing the strength 30% of broken zone to imitate the plan which reducing the strength of broken zone and the influenced zone separately can be considered as according with the actual situation and reasonably practicable,and its test results are reliable.