Engineering Characteristics Analysis Of Weak Structural Surface Below High Concrete Gravity Dam In Jinshajiang Guanyinyan Hydropower Station Its Stability Research

This article was based on the engineering geological characteristics of the weak structural plane, took the deep sliding stability evaluation as the main target, by means of data of the site investigation, laboratory analysis, field test and numerical calculation, and did a deep research on the engineering geological characteristics of the foundation F2fault and the deep sliding stability evaluation of the gravity dam of the Jinsha river Guanyinyan hydropower station. The idea of this paper was listed:According to the engineering geological environment of the dam area and large-scale excavation of its foundation, the author took a deep research on the weak structural plane which threating the stability of the dam. We learnt more about the traits of the weak structural plane by determining in advance and following the excavation and then provided a reliable geological data for the deep sliding stability evaluation. On the other hand, combined with the field and laboratory experiments, the mechanical parameters of weak layers was evaluated reasonably, then took the typical monolith to make the stability calculation and proposed appropriate engineering measures and evaluated the reinforcing effect.The achievements are as follow:(1) Based on the filed investigation, from the traits and scale of the structure, the engineering geological classification of the Guanyinyan hydropower is advised into three categories which are â…¢, â…£ and â…¤. And the engineering geological characteristics of the various types of structural plane were analyzed.(2) A lot of field experiments on the dam foundation rock mass parameters were taken to get the quick access to foundation rock deformation parameters and formulas, which is: Ln(E)=3.17Ln(Vp)-24.2At the same time, a large number of the strength testing experiments was taken on the rock mass, the concrete and the rock joints.(3) A large number of site investigation and laboratory experiments on the traits of the weak structural plane were taken, the distribution characteristics was predicted, the three-dimensional dynamic analysis was made based on the field experiments, and which was then put to the test and correction to make it accurate.(4) Large numbers of filed investigation and laboratory experiments on the weak structural plane were taken to get the basic physical indicators of it and then the laboratory simulation was made to get the strength parameters of it.(5) According to the site investigation and laboratory analysis, the author obtained the gravity sliding boundary and had done a research on the mechanical parameters of the border under different conditions and different mechanical state of the sliding surface.(6) By means of numerical calculation on the gravity dam failure process, the author had got that the failure mode of the gravity dam was:tensile failure on the dam heel rock-failure on the fault shear-heaving destruction on the resistance body. Meanwhile, research on the deformation characteristics were studied and showed that the dam deformation is stable in normal conditions.(7) The stability of the gravity dam was calculated and analyzed comprehensively, which showed that the stability factor was2.5and not meeting the requirements.(8) Combined with the stability calculation and the failure mode, the treatment measures were proposed:setting the concrete plug at the dam heel. The evaluation of the reinforcement effect showed that the stress environment had been improved and the stability factor had increased to3.3which then reached the requirements.