Engineering Geology Study For The Stability Of Arch Dam Of Jiangkou Hydropower Station

The structure of arch dam is super-static. Foundation deformation and change of temperature give much effect on the stress of dam body. So it is required more for arch dam with geological condition and dam foundation treatment. The stability of arch dam mainly depends on the support force of downstream rockmass behind abutment of dam. If discontinuity and weak intermitted layer is existed in rockmass, abutment of arch dam will slide probably under pulling force and shear force at the both side of dam. Therefore the character of discontinuity should be investigated clearly, such as strike, dip direction, dip angle, etc.There are much discontinuities in rockmass, they have different, different character, different dimension and different orient. For example, bedding plane, unconformity, schistosity, fault, fissure,etc. Which have different causes of formation, diffierent characters, different sizes and different attitudes. These discontinuities cut the rockmass into many different element masses, i.e, structuras masses. In fact, the rockmass consists of discontinuities and structuras masses. The engineering geology characters of rockmass, especially it's mechanical character not fully decided by those integrated structural masses, but in greeter degrees decided by those discontinuities which cut it, especially weekly discontinuities. So, when we analyse the engineering geology characters of the rockmass itself or proof it as the foundation of the surrounding rock, can't single according to rock itself characters which consist rockmass, it is important that considering variety character of discontinuities and their combinatorial relationship. Analyse the formation and develop process of the discontinuities and measure the mechanical character of discontinuities by the means of physical andmechanical method, forecast the formation and destructive law, according to the growth state of the discontinuities the formation of the structure mass and stratum structure, divide the rockmass into different structure types.This paper detailed discuss the engineering geology conditions of the arch dam and analyse the stability of the slope and dam shoulder by the means of rigid body limit equilibrium method. And also provide some methods and suggestions about the geological defect treatment of the dam foundation and arch stand.