| The designing theory of row piles under horizontal loads is not yet mature, people always analyze the mechanical characteristics of row piles with calculation methods for single pile, or consider them as a equal stiffness wall which is a plane strain problem. Effected by many factors, however, row piles structures have very strong spatial effect and time effect, and these simplified methods without considering all the influencing factors can not reflect the actual performance of row piles. FEM analysis with three-dimensional model can fully consider all the influencing factors and reflect the actual mechanical and deformation characteristics of row piles. The analysis results can be used to guide the optimization designing of row piles structure.This thesis studies on a pit project, gains characteristics of cement-soil and soil through compression without lateral confinement test and triaxial test, calculates and analyzes the internal force and deformation of row piles with elastic subgrade reaction method, m-method, and simulates the excavation process of pit with a three-dimensional model based on FEM software ADINA. The model's correctness is verified by comparing the simulation values and observational values. The spatial effect, time effect, mechanical characteristics and deformation law are also studied based on three-dimensional finite element simulation. The results of m-method calculation, two-dimensional finite element simulation, three-dimensional finite element simulation and filed observation are contrasted and analyzed, and the conclusion indicates that the three-dimensional finite element analysis can more completely consider all the influencing factors and more rationally reflect the actual performance characteristics of row piles and is believed to be fit for the real state.Deformation law of row piles impacted by these influencing factors, such as diameter and length of piles, cement-soil wall, and soil parameters which contains elastic modulus, Poisson's ratio, cohesion and internal friction angle, is studied by using three-dimensional finite element simulation. The results show that: the diameter and length of piles can influence the deformation of row piles most significantly. Increasing the diameter and length can significantly reduce the pile displacement, but when it's reach to a certain extent, increasing the diameter and length of piles can only impact the pile displacement slightly, so, it is not economical to reduce the displacement of row piles structure just by increasing the diameter and length of piles.Whether set a cement-soil wall or not can significantly influence the row piles displacement, so the strength of cement-soil wall should be considered in designing and calculation for row piles. Soil parameters can also influence the row piles displacement in a certain extent, among them, elastic modulus and Poisson's ratio of soil exert a greater influence on the piles, and the cohesion and internal friction angle of soil have a smaller impact. In the case of other parameters is not changed, the displacement of row piles reduces along with the increasing of elastic modulus, and increases along with the increasing of Poisson's ratio of soil. So, it is need to pay special attention to the accuracy of the value of soil's elastic modulus and Poisson's ratio in finite element simulation. |
