Model Test Study On Composite Ground Under Flexible Foundation

With the applications of composite ground under flexible foundation in engineering increasing, people pay attentions to the work character of composite ground under flexible foundation gradually. Based on actual results we can see that the work behavior of the composite ground under flexible foundation is different with the composite ground under rigid foundation.Applying the design mthod,which is applied to the rigid foundation,to the flexible foundation,the designed results are insecurity,and it caused ecnomic losses.Therefore,there are great theoretical values to study on the behaviors and design methods of the flexible foundation, along with an extensive engineering application prospects.On the basis of research of flexible foundations the contents in this paper mainly include that the model tests are used to simulate the work behavior of the flexible foundation which considers the orthogonal methord.The orthogonal tests simulate the conditions of the actual projects which devide the flexible foundation into four different parts include fill,cushion,reinforced areas and underlying layer. By changing the five inflluenced factors include the cushion stiffness, pile modulus,the replacement rate of pile, the height of the cushion, the stiffness of underlying layer, we carried out 16 different tests. Every factor includes two different levels.Considering pile-soil stress ratio and the settlements of the composite foundation as the goals,we get the orders of the factors which influce the behavior of the goals separatly. At the same time, we discussed the deformation trend of the whole system and the load transfer law by considering the composite foundation upper-lower combined action.At last,two models established by three-dimensional finite element software ABAQUS are used to simulate the behavior of the composite ground under flexible foundation. We study the law of the pile force in rigid pile composite foundation and flexible pile composite foundation separatly though applying load steply.We get that the shear stress of piles composite ground under flexible foundation relatively small, and the damage form of piles is tensile damage which is caused by bending moment.