Study On Design Theory And Method Of Secant Pile Wall Composite Structure

Currently, secant pile wall is mostly used as temporary structure in China, it is a uneconomic way that the secant pile wall is abandoned after excavation, at the same time, the abandoned pile wall is a big obstruct to the subsequent development of urban underground space. Structural style and bearing mechanics of secant pile wall are similar to the diaphragm wall and should be used as both temporary and permanent structure like the diaphragm wall. Based on the previous viewpoints and the testing project of Shanghai Metro, the research on the theory and design method of the secant pile wall composite structure used as permanent structure is studied in the paper.Firstly, the paper introduces the existing conditions of application and research in our country, and they are still in the stage of familiar with and exploring construction methods. The research on design method of the secant pile is little.Secondly, the key parameters of secant pile designed as retaining wall is analyzed in the paper. Based on the squareness of the secant pile boring and destruction feature of secant pile face, the paper delivers the calculation method of proper overlapping size of secant pile wall. The calculation method of rigidity and reinforcement of different secant pile format is also studied.Then, the paper discusses the feasibility of different secant pile wall used as permanent structure and includes that the hard/hard secant pile wall can be used as permanent structure and hard/firm as a part of permanent structure, the joints between secant pile wall and the exterior wall of the major structure are also presented. The paper qualitative discusses the additive condition of the load moment and stress on the lining and exterior wall and presents the design items needed attention under the different combination format. The paper also discussed the influence of stiffness ratio, subgrade modulus and waterproofing quality to the internal force and load sharing. Based on the study of crack resistance of secant pile wall, the paper takes checking calculation to the testing project of Shanghai Metro and advises that hard/firm secant pile wall should used with lining.And then, the inverse calculation method of bending moment of secant pile and lining based on the measured stress of reinforcement and lateral deformation is studied. The inverse calculation method is applied to analyze the internal force and interaction of lining and secant pile wall of the testing project of Shanghai Metro. The...