The Application And Research On Combined Supporting Of Cement Mixing Pile With Drilling Bored Pile

With the development of urban construction in China, more and more problem of excavation and supporting of foundation has emerged. In the soft soil area, because of the limited strength, large deformation and a certain degree of creep, the foundation supporting is even more complicated.Currently, there are kinds of combined supporting design. Among them the method of cement-soil mixing pile with double row bored pile is a novel form of supporting system with the characteristics of large lateral stiffness, good integral stability, small internal force, good pile body deformation control ability, and convenient construction. When the foundation was excavated, the soil behind the pile tended to move horizontally and vertically towards the foundation. However, since the shear strength of the soil and the friction force between pile and soil, the double row pile restrainted the movement of the soil between piles, and so did the cement-soil mixing pile to the soil body behind the foundation. Moreover, the cement-soil consolidated the soil between piles, the shear strength of the soil body was greatly improved. As a result, the soil arching effect of cement soil between the double row pile is more obvious that of the combined supporting structure. The combined supporting system is widely applied in deep foundation and soft soil area gradually.In the paper, the common supporting structural forms in foundation engineering were firstly introduced, and the designing theory of supporting structure were summarized, the mechanisms of combined application of cement-soil mixing pile with double row bored pile in soft soil foundation, especially the soil arching effect were discussed. Based on this, a large foundation engineering in Shanghai was taken for instance, the stability of the foundation was calculated and mechanism of local deformation was studied by finite element analysis. Subsequently, the solutions and measures of problems related to the quality of construction were put forward. The study could be referred to the design and construction of combined support of cement soil mixing pile and double row bore pile in soft soil area.