Stability Analysis Of Dam And Its Foundation

Dams are important hydraulic structures. With the rapid advancement in science, technology and economy high dams are becoming more sophisticated; the geological conditions and the behaviors of the supporting foundation are becoming complex. Therefore, dam safety evaluation demands close attention among dam Engineers. Great strides have been made in the area of strength, deformation and stability analysis of dams. The development of computers, robust theories and methods of analysis has brought about considerable changes in the computational aspect of dam stability analysis. Analysis can be done much more thoroughly and accurately. This thesis is focused on the stability analysis of dams and it foundation, two methods are employed:(1) Stability analysis method base on rigid limit equilibrium method, which regards dam and rock foundation as undeformable rigid body.(2) Stability analysis method base on elasto-plastic theory. It's employs numerical method to analyze stresses and strain of structure and its foundation. Its evaluate stability according to stress and strain field.In the past, the safety factor and stresses of assumed potential sliding faces are computed directly (direct method). For a complex rock foundation, the evaluation of shapes of sliding faces, location, distribution and direction is quite a difficult task.Several ways of stability appraisal exist: (a) Reduce shear strength method; its reduces shear strength parameters ( c and φ) of the materials (b) Overload method, it increases all loads gradually from minimum to maximum level as times progresses until failure occurs. In this study, two methods were considered; the direct and indirect methods. In the indirect method, the shear strength parameters are incrementally reduced until failure occurs. The stresses and strain are analyzed by MARC software; the safety factors evaluated based on displacement, yield region (connected) and total energy criteria. In the direct method, safety factor is evaluated using computer program written in FORTRAN LANGUAGE based on rigid limit equilibrium equation. The analyses procedures of the above two methods was use to study the stability of Xiangjiaba gravity dam. Sensitivity of the dam behavior to materials parameter changes was also studied. The safety factors computed from both methods were compared It was revealed that, the failure of engineering structures does not only depends on the impose load but also, on the constitute materials behavior.