Abstract: With the development of testing technology, geomechanical model test has become an important method for stability and safety analysis of high arch dam. According to the similarity theory, a 3D geomechanical model with the proportion of 1∶200 was built up to simulate the arch dam and foundation, main faults, crack zone and other major geological condition. Destructive test based on overloading of hydraulic pressure was used to analyze the stress, deformation and stability of arch dam, foundation and abutment resistance body, and to study the stability of arch dam foundation, the process of instability and failure and overload capacity. The results were compared with the research results of domestic similar high arch dams, and a comprehensive evaluation of safety degree of Yangfanggou dam foundation stability was put forward. The results showed that, the safety degree of arch dam cracking was 2.5~3.0, the safety degree of nonlinear originated was 4.0~6.0, the limited safety degree of global stability was 11.0, which indicated the high global stability of Yangfanggou dam and foundation.

Key words: geomechanical model, global stability of dam and foundation, overload test, Yangfanggou hydropower station

摘要： 随着试验技术的发展，地质力学模型试验已成为研究高拱坝整体稳定性和安全度的重要方法。依据相似理论，按照1∶200比例建立杨房沟水电站整体三维地质力学模型，模拟拱坝-基础及两岸主要的断层、节理裂隙及风化卸荷等地质条件，采用水压超载法进行破坏试验研究，分析拱坝、基础及两岸坝肩抗力体的应力、变形和稳定安全度，研究拱坝-基础整体稳定性、失稳破坏过程及超载能力，并与国内同类高拱坝研究成果进行对比分析，综合评价杨房沟拱坝-基础整体稳定安全度。研究结果表明，拱坝起裂安全度K₁=2.5~3.0，非线性开始安全度K₂=4.0~6.0，整体稳定极限安全度K₃=11.0。可见，杨房沟水电站拱坝-基础整体稳定性较高。

关键词: 地质力学模型, 拱坝-基础整体稳定性, 超载法试验, 杨房沟水电站