Application And Study Of SMW Method In The Foundation Pit Support

SMW engineering method is a new method used for foundation pit support introduced in recent years, which is made up of soil-cement piles joined each other with the steels inserted in them. This method have the characteristics of small floor area, good impermeability, etc. But because of the faultiness of division theory and other reasons, SMW engineering method is limited in its spread and application in China.In this paper, the calculation method of supporting structure is studied deeply. The construction process of the foundation excavation is simulated and analyzed by using the software ABAQUS, and the results of simulation are compared with field monitoring date. According to monitoring date, calculating result conform result of site. Therefore calculating result by using finite element software ABAQUS is believable. With the spatial finite element analysis, many factors such as the diameter of the soil-cement mixed piles, the space of the steels and the steel section were studied. The major research results are as follows:(1) Pile horizontal displacement and steel stress are both increased with the increasement of excavation depth, because of the bracing beams, pile maximum horizontal displacement occurred in the bottom of foundation pit, the steel stress is tension on the upper part, compression on the lower part.(2) Additional load on the top of foundation pit has greater influence on the support structure, the additional load is and the farther distance from the edge of foundation pit, the smaller of pile horizontal displacement and steel stress is, and the better to supporting structure. In the construction, try to control the additional load, and keep it far away from the edge of the foundation pit.(3) The difference of the space of the steels has a great influence on pile horizontal displacement and steel stress, the denser the steel is, the smaller the pile horizontal displacement and steel stress are.(4) Due to the soil-cement mixed piles around the steels, changing the thickness of steel section in a certain range have little influence on the pile displacement, and changing the pile length with meeting the minimum embedded depth both have little influence on the support structure, so change the pile length and the steel section has minor effect on improving the support structure deformation and internal force. (5) Lowing the position of the bracing beams and increasing the diameter of the pile could reduce the pile horizontal displacement and steel stress, and do favorable effects to retaining structure.(6) The simulation value of pile horizontal displacement and steel stress is smaller than the the results of design calculations.The analysis results show that spatial finite element analysis of exvacation process is necessary in such complex problem. The study result has guiding significance for design and construction of foundation pit supporting projects.