Bearing Performance Analysis And Optimization Method Research Of DJM Pile Composite Foundation

With the continuous infrastructure expansion and the rapid development of ground improvement technology, the Dry Jet Mixing(DJM) pile composite foundation has made considerable progress in theory and practice. Nevertheless, theoretical study is also far from enough to meet the needs of practice. There are still many problems need to be solved.Bearing performance of the DJM pile composite foundation is studied by way of field static load tests, pile-soil stress ratio tests and the interior strength test of cement-soil. The mechanical properties and deformation characteristics of DJM pile has been significantly improved after reinforcement. It can be seen that the reasonableness of calculation and the reliability of construction are verified to obtain a more objective and reliable description of bearing performance. Meantime, time-effect of the DJM pile's bearing capacity is proposed.Analyzing bearing performance of the DJM pile composite foundation by the plane strain finite element method, the load-sharing of soil and regularities of pile-soil stress ratio with the changes of the factors are reflected. Comparing to field test results, the practicality of the finite element method has to be verified.Optimization method is a way to make the objective function achieve the minimum value in a controlled environment. Based on the sensitivity of design variables for objective function, optimization of the DJM pile composite foundation is studied by the way of first-order method of ANSYS software. At the premise of satisfying the demands of strength and deformation, an??ment consumption as to be the objective function,influences of design variables on bearing capacity and deformation are analyzed. Optimization combination of pile length, replacement ratio and cement ratio can be calculated, which can be suitable for ground improvement in Yellow River Delta region.