Application And Research For Steel Pipe Piles During Mixing Pile Composite Soil Nail Wall

As one of the most common form of foundation pit supporting, Soil nailing wall supporting system has been widely used and the rapidly development in recent years. but using soil nail as soil reinforcement measures singly, not only usually unsuitable in the engineering, but also limit the improvement of stability and the control action for foundation pit deformation. During engineering practice, soil nail were used together with other forms of supporting, such as mixing pile composite soil nailing wall, steel pipe pile composite soil nailing wall, mixing pile + steel pipe pile composite soil nailing wall and so on. Through the validation of practice for a long time, these form of foundation pit supporting could meet the engineering requirements well. Existing research results, although admit the significance of steel pipe piles during mixing pile composite soil nailing system, the effect and mechanism of steel pipe piles is not clear.In this paper, the author established three-dimensional models of Midas GTS to simulate the engineering practice of inserting steel pipe piles during the mixing pile and without steel pipe piles in the mixing pile. The author discussed the mechanism of steel pipe piles in mixing pile composite soil nailing wall, the deformation of foundation pit, soil nail axial force and the stress of pile and soil. Concluded: steel pipe piles in mixing pile can effectively control the development of deformation in foundation pit. In the other way, deformation pattern also appears many difference. After inserting steel pipe piles during mixing pile, the effect to control the bottom uplift is not obvious, the contribution of uplift resistant still mainly come from mixing piles. This paper provide certain guiding significance to the engineering practice of inserted steel pipe mixing piles composite soil nailing wall.