小湾高拱坝整体稳定三维地质力学模型试验研究

 结合小湾高拱坝坝肩坝基的地形、地质特征、软弱结构面分布状况、浅层松弛卸荷现象以及加固处理方案，建立三维地质力学模型，研制主要断层的变温相似材料，运用超载与降强相结合的综合法对整体模型进行破坏试验。通过试验获得小湾拱坝坝肩坝基的变形特征、失稳的破坏过程、破坏形态及破坏机制，得到强度储备系数为1.2，超载系数为3.3～3.5，确定拱坝坝肩坝基整体稳定综合法试验安全系数为3.96～4.20。对试验数据的综合分析得出，两坝肩中上部高程部位由于对断层和蚀变带采用了混凝土洞塞置换，其变位相对较小，破坏形态和破坏范围相对较轻，说明混凝土加固洞塞置换起到较好的加固效果。根据试验显示的破坏形态和破坏区域，建议对右坝肩下游1 245 m高程以上的断层F11和F10做一定范围的处理，对左坝肩推力墩以上部分岩体进行适当的加固处理。

EXPERIMENTAL STUDY OF 3D GEOMECHANICAL MODEL FOR GLOBAL STABILITY OF XIAOWAN HIGH ARCH DAM

According to the topographical，geological features，the distribution of weak structural，shallow relaxation unloading phenomena and reinforcement program of Xiaowan high arch dam，the 3D geomechanical model is set up；and a kind of model test material called temperature analogous material whose strength varies with temperature in the process of experiment is developed to simulate the decrease of the major weak structural planes. Then，the failure test is carried out by comprehensive method which considering both overloading and strength-decreasing. Through the test，the deformation characters of dam foundation and abutment，the failure process，modes and mechanism are obtained. The safety evaluation of model experiment indicates that the strength margin coefficient is 1.2 and the overloading coefficient is 3.3–3.5；and the global factor of safety for the dam foundation and abutment is 3.96–4.20. Synthetical analysis of test data indicates that the displacement，failure status and zone of mid-upper abutment are relatively less due to the excellent reinforcement effects of concrete displacement plugs on faults and alteration zones. Based on the failure status and zone in the model test，some suggestions are proposed that the faults F11 and F10 above the elevation of 1 245 m in the right abutment and the rock above the thrust block in the left abutment should be reinforced.