An Applied Study On Cement-Soil Column And Cast-in-situ Pile Composite Retaining Structure

In this thesis, the characteristics of the foundation pit, the development of the type of the retaining structure was introduced, and the theory and design method of cement treated gravity retaining wall was discussed especially. Then the horizontal bearing capacity of reinforced concrete cast-in-situ pile was introduced. A new type of retaining structure consisted of cement treated gravity retaining wall and cast-in-situ pile was introduced, the design method and its applicability was analyzed. And then , an example of this method applying on the second stage of Shengshiyuan project is taken, technical and economical analysis of the design was analyzed compared with the that where cement-soil retaining wall was applied. Calculating results show that the safety against overturning and sliding of this new type of retaining structure was greatly improved because of the large embedment of cast-in-situ pile, meanwhile the width of cement treated gravity retaining wall was reduced and much money was saved. When the depth of foundation pit is less than 4.5m,the cast-in-situ pile can play a great role in the capability of this new type of retaining structure against overturning, on the contrary, if the depth of foundation pit is more than 6.0m, the cast-in-situ pile can play only a little role, it can only share no more than 10 percent of the bending moment acting on the whole retaining structure. So the new type of retaining structure can only be applied to the foundation pit that is less than 6m deep.Composite retaining structure consisted of cement treated gravity retaining wall and cast-in-situ pile was a new type of developed these years, some suggestions were provided to the design of this new type of composite retaining structure.