Local Failure Mode Analysis For The Key Area Of High Arch Dam

High arch dam is a kind of complex concrete structure.Dam heel, dam toe and the fault belt in the foundation of the dam are all the possible failure regions, and a plurality of failure zone may exist at the same time. Failure behavior of a structurealways starts from the local damage, and grow to the overall buckling. This problem involves two aspects, how to determine the occurrence of local damage location and how the local damage develops. The main research results of this paper are as follows:(1)Presents anfailure mode analysis method for the key areas of high arch dam. In this method, the deformation reinforcement theory is used, combined with submodel method. First of all, the deformation reinforcement is used to determine the key areas of high arch dam. Then hese key region is modeled by a fine mesh, to analyze the failure mode of this area.This analysis method is applied to the numerical model for the simulation of Baihetan arch dam. On the base ofthe global stability, the unbalanced force of the dam heel and the rock mass foundation, the failure location is determined. Then the submodel is created and analysised for the dam heel and the fault in the bedrock.(2)A crack propagation simulation method is developed based on the combine of the lattice model and the finite element method. Finite element mesh can be transformed into a lattice modelautomatically at the zone where the crack initiates.So the high efficiency of the finite element method in the conventional calculation and the convenience of the lattice model in the crack processing area will be both contained. In the initial model, it will not be necessary to specifythe cracking area, the element with the calculation stress exceeds the tensile strength will be broken and the area to be transformed into a lattice model, which is used to simulatethe crack propagation. At the same time, this method is used to simulate the equivalent elastic modulus of jointed body.(3)Anchoring effect of the prestressed anchor cable to the slope is analysised. It contains two aspects: the effect of prestress and the effect of resistance to deformation.The prestress is shared equallyin the slope body, which lead to an average pressure, the effect of resistance to deformationis realized by adding the cable stiffness into the whole stiffness matrix. A slop model is calculated, and the plastic complementary energy, the unbalanced force and the surface deformation of the slope are compared between the original slop and the slop enhanced by a group of prestressed cable.(4)Based on the thermodynamic described by internal variables, the stability of plastic critical point is discussed. The result shows that the behavior of a material near the critical point is totally controled by the geometric structure of free energy function.At the same time, the Drucker postulate and the Ilyushin postulate are discussed on the basis of thermodynamics, the two postulates can be unified based on the definition of thermodynamics.