| The calculation of earth pressure is an important and old issue. Classical earth pressure theories enunciated by Coulomb and Rankine have been widely used because of its simple calculation and clear mechanics concept. However, because of its excessively simplify, the calculation result doesn't accord with in-site data under the complicated condition. Furthermore, unsaturated soil is different from saturated soil, which is composed of four-phases medium, and brings on the different engineering behaviors. But engineers still used Rankine theory to calculate the unsaturated soil pressure. Therefore, based on forepassed achievements, the computation of earth pressure and application of intelligent optimization method are studiedFor universality soils, composite (logarithmic spiral and planar) fail surface is considered. The formulae for calculating active earth pressure and passive earth pressure are obtained by using thin-layer element method. Considering seismic effect, the active and passive soil pressure formulas are obtained by using wedge-shaped element method. Complex simulated annealing calculation method and complex genetic algorithm are used to determine the potential fail surface. At the same time, the influence of calculation parameter on earth pressure are discussed.For unsaturated soils, based on extended Mohr circle, considering the influence of matric suction on earth stess, unsaturated soil active earth pressure calculation formula used thin-layer element method is educed. And unsaturated soil passive earth pressure formula used by wedge-shaped element method is also put forward. Similarly, improved complex genetic algorithm and complex annealing algorithm are used to search for potential slid surface.In foundation pit engineering, the retaining will generate big displacement and flexural deformation, which was subjected to earth pressure, and the earth pressure will redistribute. On the basis of fully considering interaction of structure and soil, a function to describe the relationship between earth pressure and wall displacement is used, stress redistributing caused by soil arching action also being considered. Then, the earth pressure computational method considering displacement is obtained. The method can compute soil pressure in non-limit state. Based on the exerted efficiency of rock bolt's stiffness ,the Newmark numerical method and the elastic foundation beam method considered the surcharge at the bottom of pit posed by the active slide... |
PDF Full Text Request