Experimental Research On The Long-term Horizontal Bearing Capacity Of Multi Arch Bridge Pile Group Foundation

Large-span multiple-arch bridge has advantages of beautiful appearance and strong span ability.As an important supporting structure of the multi-arch bridge,the horizontal bearing capacity of the pile groups is very important to the safety and long-term stability of the project.At present,the researches on the long-term creep effect of pile groups are still inadequate for the needs of engineering practice.Therefore,it is necessary to carry out a relevant theoretical and Experimental Research on the long-term bearing capacity of pile group foundations.The main contents are as follows:Indoor model tests of single pile and pile group foundations were carried out to simulate the pile-soil interaction characteristics of the pile foundations.The tests consist of one ultimate bearing capacity test of single pile,three long-term horizontal load tests of single pile for different load level,and a long-term horizontal load test of group pile foundation.The development of pile-head displacement;the distribution and development of bending moment,shear force and soil pressure of the foundation;the coefficient of pile group effect and the reduction factor for each pile comparing with the single pile under the same load level were found according to the test results.In this paper,the p-y curve model considering the long-term creep effect of soil is established,and the formula for calculating the long-term p-y relationship is proposed,which takes the soil parameters,the depth,the load level and the pile group effect into account.According to the comparison between the calculated results and the experimental results,it is considered that the theory can simulate the creep deformation of pile foundation,and is relatively conservative.The long-term displacement of the pile group foundation is calculated based on the project example,which provides the reference for the engineering design.