高拱坝坝肩坝基整体稳定地质力学模型试验研究

锦屏一级水电站是雅砻江干流上的重要梯级电站。工程主要开发任务是发电，同时还兼有拦沙、防洪、蓄能作用。该工程大坝为混凝土双曲拱坝，最大坝高305m，为目前世界上最高拱坝。坝址区地质构造复杂，两岸谷坡为近千米的高陡边坡，两坝肩岩体内存在断层、煌斑岩脉、层间挤压带、深部裂隙等各类软弱结构面，对拱坝坝肩坝基稳定带来不利影响。采用三维整体地质力学模型试验研究方法，研究了锦屏一级高拱坝坝肩坝基的整体稳定性。试验中充分考虑了影响坝肩坝基稳定的各种因素，既考虑拱坝上游超载情况，同时还重点模拟两坝肩岩体中软弱结构面强度弱化的影响，为此研制了适合该工程的变温相似材料及试验模拟新技术，并在一个模型上进行了强度储备与超载相结合的综合法试验。通过试验获得了坝肩坝基的变形及分布特征、失稳的破坏形态和破坏机理，确定了拱坝坝肩坝基整体稳定安全度为4．7～5．0，评价了工程的安全性，并针对坝肩的薄弱环节提出了加固处理措施建议。

EXPERIMENTAL STUDY ON GLOBAL GEOMECHANICAL MODEL FOR STABILITY ANALYSIS OF HIGH ARCH DAM FOUNDATION AND ABUTMENT

Jinping First Stage Hydropower Station is an important cascade hydropower station located on Yalong River in Sichuan Province. The primary mission of this project is to generate power and meanwhile to intercept sand, control flood, store energy. The project adopts a 305 m concrete hyperbolic arch dam which is the highest arch dam in the world. The geological structures in dam site are very complex and the height of the slope is about 1 000 m. There are many different weak structural planes in rock mass of the dam foundation such as fault, lamprophyre dike, innerlayer compressed zone, deep-seated fracture, which are disadvantageous to the stability of the dam foundation and abutment. The global geomechanical model experiment is conducted to study the stabilities of the dam foundation and the abutment of Jinping First Stage Hydropower Station. The model considers the various factors influencing the stabilities of dam foundation and abutment during test, which includes overloading as well as strength-decreasing of weak structural planes in the rock mass of the dam foundation. A kind of model test material called as temperature analogous material whose strength varies with temperature in the process of experiment is adopted to simulate the decreasing of the weak structural planes. The temperature analogous material and model test technique are developed for the first time. Then, the comprehensive method that considers both overloading and strength-decreasing is successfully applied to the model. Deformation characters,failure conditions and mechanisms of the dam foundation and abutment are achieved. The safety evaluation on the model experiment indicates that the global safety factor for the dam foundation and abutment is 4.7-5.0. In addition, the reinforcing measures for the weak areas are advised.