基于地质力学模型试验的大岗山拱坝整体稳定性分析

 地质力学模型试验是研究拱坝整体稳定性的有效方法，采用250∶1的模型比例尺对有基础处理的大岗山拱坝进行三维地质力学模型试验。通过小块体砌筑技术模拟裂隙岩体的变形和强度、坝基不连续结构面以及坝基处理措施；通过油压千斤顶加载系统施加坝面水荷载；采用的数据采集系统能及时、高效地测量坝面应变、坝基岩体外部位移和内部相对位移，并自动存储数据。采用超载水容重法进行超载破坏试验，得到拱坝坝体位移和应力的分布规律以及坝体和坝基岩体的开裂破坏过程。采用3个特征超载安全系数K1，K2和K3对大岗山拱坝整体稳定性进行评价。通过地质力学模型试验和基于变形加固理论的三维数值模拟对比分析表明，大岗山拱坝整体稳定性较高，并得到对拱坝–坝基整体稳定起控制性作用的部位。

GEOMECHANICAL MODEL TESTS ON GLOBAL STABILITY OF AN ARCH DAM AT DAGANGSHAN

The geomechanical model test is an effective method to study the global stability of arch dams. The geomechanical model test on the arch dam with foundation reinforcement at Dagangshan in the similar scale of 250∶1 was conducted. The deformation and strength of jointed rock mass，the discontinuous structural surfaces and the reinforcement measures were simulated through the masonry technique of small blocks. The water load imposed on the dam surface was controlled by the hydraulic jacks. The strains and displacements were collected and saved automatically and effectively with a data acquisition system of high accuracy. The high water pressure method was employed for the overload failure test. The stress and displacement distributions of the scaled dam were obtained and the failure processes of the scaled dam and the abutment were explored. Three factors of the global overload safety K1，K2 and K3，were used to evaluate the global stability of dams. The comparative analysis between the geomechanical model test and the numerical simulation based on the deformation reinforcement theory indicated that the global stability of the arch dam at Dagangshan was relatively high. The weak areas controlling the global stability of the arch dam was located.