Study On Complex Dam Foundation Treatment Analysis Of Hydropower Project Based On 3D Geological Analysis Model

The engineering geological conditions of the dam foundation of Guan Yinyan hydropower project are quite complex. The dam foundations are consisted of soft and hard layered rock masses alternately distributed where occasionally exist corrosion phenomenons in some area. To build a RCC gravity dam with a height of nearly 160m under such complex foundation condition, it is quite necessary to recognize the characteristics of the complicated rock masses and provide feasible foundation treatment scheme according to scientific calculation and analysis to ensure the project safty.In this paper, aiming at the complex engineering geological condition of Guan Yinyan hydropower project, a 3D geological analysis models are established which expressed integrated geological information of the dam foundation including alternately distributed soft and hard layered rock masses and occasionally existed corrosion. The stress and deformation characteristics of the dam and its foundation under different calculation conditions have been mainly studied. Considering the uncertainty of karst development, the influence of regional distribution of corrosion on dam safety is researched using the SFEM simulation analysis method. The optimal dam foundation treatment measure is proposed according to computing, analyzing and evaluating these proposed dam foundation treatment measures.The main research contents and achievements are as follows:(1) 3D geological analysis models of Guan Yinyan hydropower project are established considering soft and hard layered rock masses alternately distributed where occasionally exist corrosion phenomenons in some area. The refined 3D visualization analysis research is carried out through the 3D geological analysis models. The finite element model of the whole 3D geological models, which can completely simulate dam foundation rock mass characteristics of soft and hard layered rock masses alternately distributed, corrosion development and various structure surface combination, is set up adopting numerical simulation method.(2) By applying the finite element structure numerical simulation analysis method, static and dynamic characteristics of dam body and foundation is reasearched under the complex layered bedrock condition where occasionally exist corrosion phenomenons in some area. The computation results with or withnot corrosion region in dam foundation are compared and analyzed. (3) Based on analyzing the influence of corrosion distribution on dam body using entity simulation method, considering the material randomicity and position randomicity of corrosion region, the influence of regional distribution of corrosion on safety of the typical dam section is researched using the FEM simulation analysis method.(4) The whole random field of corrosion distribution in dam site region is established based on the random field theory. And several regression models, which reflect the distribution frequency of dissolution pore with the elevation change, are built through choosing the type dam section. The best regression model can be confirmed and some schemes can be obtained. By computing using the FEM, the stress and strain results of multiple schemes are acquired, which can be used to estimate the security of the typical dam section.(5) Several foundation treatment schemes are proposed based on 3D geological analysis model. These schemes are compared and evaluated through 3D nonlinear finite element sensitivity analysis. The optimal dam foundation treatment measure is confirmed, which can provide some references to engineering design.