Model Test Research And Numerical Simulation Analysis Of The Interaction Of Pile-soil By SMW Engineering Method

With the development of urban construction, lots of deep foundation pits have come forth continuously. As a new support structure for foundation pit, SMW engineering method is widely used due to its especial advantages, but the mechanism of pile-soil interaction of SMW engineering method is still unclear, so it is of great practical significance to study SMW method.According to the support of SMW engineering method, the mechanism of its pile-soil interaction is studied by model test study and three-dimensional FEM in this paper. The specific contents include the following works:1. The displacement of piles top, the lateral earth pressure and pile stress of the test model are tested under different excavation situation. The results of displacement mesurement show that the deformation process of support structure can be devided into four phases, that is, original phase, stabilization phase, displacement leap phase and breakage phase. By combining with its mbeded depth, the reasonable embed ratio of the cantilever retaining can be obtained, and its value is 0.66. In addition, the relationship between displacement and time shows that the deformation of the support structure for soft soil foundation pit is significant.2. The transverse action of cement soil is studied by energy method. The results show that the ratio of the height of cement-soil wall to the side length of foundation pit has significant influence on the effect, and the analytical solution of the maximum displacement value of pile top in view of lateral Contact relation is obtained.3.The test results are discussed in terms of the distributing of earth pressure, the variety with excavation situation, comparing with Rankine limit earth pressure, along with the relationship between earth limited pressure and displacement. The results show that the distribution of earth pressure in depth for the test wall is trapezoidal. The factual passive earth pressure is less than the Rankine passive earth pressure, the suggested value is 1/3 to 2/3 of its value, while the active earth pressure is a little more than Rankine active earth pressure. Also the needed value of the displacement and its rate of pit top for active limited earth pressure for the model test are obtained.4. Comparing the measured stress and strain of pile to the calculated values without regard to the work of cement soil, the contribution of cement soil to the rigidity of pile body can be seen, is important, its contribution can be considered in appropriate extent. A suggestion is that of a appropriate contribution of cement soil can be considered in the designing of support structure by SMW engineering method.5. The test is numerically calculated by MIDAS/GTS. In addition, the comparison of calculated results and measuring results are conducted.