Analysis Of The Causes Of Axial Cracks In Right-bank Of The Three Gorges Hydropower Station

The underground tunnels of right-bank of the Three Gorges of Yangtseriver are located in the right bank. Its workshop hole pressured and parallelly disposed by one engine with one hole. There are some disciplinary axial cracks which located in haunch and bottom lining of the underground tunnel during construction period, especially in the third and fourth holes, It is necessary to search for the causes of cracks for preventing and repairing. The emulation analysis of the first hole is presented in this paper because the third and fourth holes hadn't inter observe apparatus during construction phase, the rational results provide feasible way for the other holes' preventing and repairing.Firstly, Optimization back analysis of parameters is carried out based on the datas of practical measure, because in this project the parameters of concrete neither testing nor practical datas. In this way, the establishment of the error function and the select of the optimization are important. During the optimization back analysis of parameters, Emphasized develop and analyzed the minimum two-multiplied back analysis. In accordance with the practical engineering, in this paper, the author mend it through time's effect and measureless. Secondly, Organizing the corresponding program and validated the program through examples. On the other hand, analyze different questions in detail that existed in the back analysis. DFP method is systematically presented in this paper.Back analysis of thermal and mechanics parameters are carried out by using DFP method and improving minimum two-multiplied error function based on the practical datas of temperature and strain of the hole. In accordance with the water tunnel that liner have cooling pipe, Thermal insulation temperature rise model adopt difference expression during its through or not water phase, and optimization back analysis of parameters is carried out.It is truly to reflect the law of distributing of reality transformation, temperature and stress, the genetic analysis of liner concrete is carried out base on this. The emulation analysis of unstable temperature and creep stress fields of the difference work conditions that cause cracks are carried out in using 3D and 2D nonlinear finite element method. The factors that probably leads to cracks are put forward based on the analysis, which in turn are: the deformation of surrounding rock and the deformation of concrete volume and the pelter of air temperature and thermal insulation temperature rise and the thickness of liner and cooling pipe. The rational results provide a feasible way for the similar projects analysis in the future.In accordance with the practical engineering, the foundation and the holes are meshed with different element. For this problem, compatible displacement method of different mesh is presented in this paper. On the other hand, the mechanism of the creeping is analyzed.