锦屏一级高拱坝坝基结构面弱化效应研究及坝肩稳定性分析

Study on weakening effect of structural plane and stability analysis of Jinping I high arch dam

为了研究锦屏一级高拱坝工程在蓄水运行后,坝肩坝基软岩结构面在应力场、渗流场耦合作用下的弱化效应,以及在考虑这种弱化效应条件下分析高拱坝工程的坝肩稳定问题,首先通过现场采集该工程坝肩软岩和结构面岩样,制备相似试件,在MTS岩石力学测试系统上进行水岩耦合三轴压缩试验,获得了坝肩软岩和结构面强度参数的弱化率,为拱坝坝肩稳定模型试验提供结构面降强幅度的依据。然后,针对拱坝坝肩稳定问题,开展了加固地基条件下高拱坝三维地质力学模型综合法破坏试验,在试验中,根据弱化试验成果确定了结构面的综合降强幅度为30%,并研制了适用于各类软弱结构面强度弱化特性的变温相似材料,用于在模型中模拟结构面的弱化效应。通过试验获得了坝与地基的变形分布特性,坝肩坝基失稳的破坏形态和破坏机理,得出坝肩稳定综合法试验安全系数为5.2~6.0,评价了拱坝工程的稳定安全性。研究成果为工程的设计施工和安全运行提供了重要科学依据。

In order to quantitatively reveal the weakening effect under thousands of tons of water load andlong-term effect of complexity seepage field after the project put into operation,as well as to reasonably re-consider the weakening effect in evaluating the dam abutment stability of Jinping I high arch dam,firstly,the weakening effect experimental research was carried out in this paper. In the experiments,the dam abut-ment rock samples of weak rocks and structural planes of Jinping I high arch dam were collected,and thesimilar specimens were prepared, then the triaxial compression tests and the water-rock coupling triaxialcompression tests were conducted in the MTS815 Rock Mechanics Testing System. Through the tests, theweakening rates of weak rocks and structural planes were obtained,which provide the basis for determiningthe strength decreased range of weak structural plane in the dam abutment stability research of JinpingⅠarch dam. Secondly, in order to study the dam abutment stability of the high arch dam under reinforcedfoundation conditions,the three-dimensional geo-mechanical model comprehensive method test has been car-ried out. In the experiment, the integrated strength decreased range of weak structural plane was deter-mined as 30% according to the weakening test results, and in order to simulate weakening effect of rockmass and structural plane of dam abutment and dam foundation,the temperature analogous materials appli-cable to all types of weak structural plane strength weakening characteristics have been developed. Throughthe geo-mechanical model comprehensive method test, the deformation characters, the failure process, pat-tern and mechanism of dam rocks and structural planes in foundation and abutment are obtained. And thedam abutment stability of comprehensive method test safety coefficient are determined as 5.2~6.0. Evalua-tion of the stability and security of the arch dam project has been done. The research results provide an im-portant scientific basis for the design,construction and safe operation of the project.