Study On Numerical Simulation Of Crack Growth Of Gravity Dam Based On XFEM

The extended finite element method (XFEM)is a numerical method for modeling discontinuities within a standard finite element framework. It was first introduced by Professor Belytschko at Northwest University in 1999. It Bases on the partition of unity methods and finite element method. The crack growth in the gravity dam can be modeled by XFEM without making the crack surface associate with the finite element mesh and setting dense mesh near the crack tip as well as remeshing after crack growth. Soft clay of fracture process zone in concrete are considering and maximun circumferential stress criterion applied, and XFEM is used for modeling fracture process of concrete dam, which bases the distinct advantages of XFEM for fracture analysis. The principle contents and achievements in the dissertation are as follows:(1)The basic theories and techniques of XFEM for fracture analysis are researched. Computational methods of stress intensity factors useing XFEM are investigated, in which calculation and exact solution are adopted and method are validated by one examples. Thus results by XFEM can he shown visually.(2)XFEM is used for modeling crack growth of classical test model, in which calculation and exact solution are adopted and validate the feasibility and accuracy of numerical simulation of crack growth. The predominance and characteristics of specific application of this method for linear elastic fracture mechanics analysis is displayed. The effect of different dam foundation elastic constant, passageway and grid-density distributing in the crack is studied and some useful conclusions are obtained by comparisons.(3)A three-dimensional solid model of spillway section in Xierheâ…¡hydropower station is established and computed field was meshed by structural grid of hexahedral cells. The effect of crack on stress and displacement in dam was researched and the sensitivity analysis of concrete tensile strength were carried out.