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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。
Jinping a high arch dam high reservoir, dam site complex geological conditions, the dam and the foundation of the overall stability outstanding. After the impoundment operation, the strength of dam abutment structure and weak rock mass will decrease under the long-term action of high stress and strong seepage pressure, which is more unfavorable to the overall stability of arch dam. In order to evaluate the post-reinforcement engineering safety, weakened the strength of each weak structural plane under different conditions by the water-rock coupling triaxial test. On this basis, the comprehensive geomechanical model test was used. Due to the limitation of the test technique, the zoning of the structural surface can not be achieved to reduce the broken belt and the strength of the influence belt. Based on all the factors, the model test finally uses the broken belt to uniformly reduce the weakening plan by 30%. Aiming at the effect of strength weakening effect on the overall stability of the weak structural plane, the 3-D nonlinear finite element software is used to calculate and analyze the unified reduction of the broken belt by 30% (Scheme 1), the broken belt and the zone zoning degradation (Scheme 2) By comparing the calculated results of two schemes, the displacement of dam 2 under normal working conditions is increased by about -0.2% -2.24% compared with that of solution 1, and the displacement of dam abutment is increased by about -2.35% -1.72% Under the condition of displacement, the increase of dam body is about -4.68% ~ 9.23%. Under the two schemes, the displacements and failure processes of dam body and dam abutment are similar, with similar magnitudes and similar results. According to a comprehensive analysis, it is reasonable and feasible to simulate the broken belt and the impact belt with 30% reduction in the crushing zone unifiedly for the model test of Jinping I Arch Dam, and the test results are reliable.