Analysis On Vertical Force Behavior And Thermal Stress Of Pile Groups

Along with the construction development in high-rise buildings and large bridges in china, pile foundation are widely used in these projects for their high bearing capacity and good adaptability. However,the studies of pile foundation principally focus on the analysis for the bearing behavior of single pile foundation,and the bearing character and pile group effect of pile group foundations have not been well understood. Therefore,the corresponding indepth research needs to be carried out. In this article, the studies are emphasized on the force characteristics of pile groups under each construction stage loads and its temperature field and thermal stress after concrete has been cast.The main research works consist of the following parts.(1) According to the forms of pile groups and the surrounding soil distribution situation of a bridge, the field test scheme and the field test were made,and the force changes of each construction stage were measured of the pile body, pile tip and the underside of the pile cap.The distribution rules of pile axial force,pile friction,tip resistance and resistance of pile cap bottom were analysed during each construction stage.(2) Based on the commercially available finite element analysis program ANSYS, the three-dimensional simulation model of the pile groups was established. The pile used Solid45element and elastoplastic constitutive model,soil used used Solid45element and Drucker-Prager model to simulate the pile-soil force under the vertical loads.The correctness of the model was checked by comparing model data with test data.(3) It was measured on temperature changes of the pile groups after concrete has been castBased on the commercially available finite element analysis program ANSYS,the pile groups model was established to simulate the temperature field and thermal stress of the pile groups at1st,2nd,3rd,4th,5th,6th,7th,8th,30th,60th,90th,150th day after concrete has been cast.Analysis the different mold temperature in temperature field and thermal stress of the pile groups,reached a reason able temperature into the mold.