The Stability Analysis And Monitoring Research Of “T-type Combined Steel Sheet Pile” System

The tight project schedule, large deep excavation, small construction space and complicated surrounding conditions have become the basic characteristics of the current projects and greatly increased the difficulty of building foundation pit. Many of the accidents to the instability of foundation pit and collapse frequently occur in the current projects because of unreasonable supporting design and inappropriate way of support. At present, the use of soil nailing wall,deep-mixing piles, cast-in-place piles, underground continuous walls and three axis method is mature in support of foundation pit. But a single traditional construction method is not good to solve all the problems that exist in the foundation pit supporting. It needs to use a combination of two or more methods in many cases. As the steel sheet pile is introduced in the foundation pit supporting, it is quickly applied due to the advantages of fast construction speed, good sealing water effect and small construction space. Steel sheet pile belongs to the flexible structure and produces large deformation in the process of supporting. So it needs inner support or anchor pile to ensure security and stability in deep excavation engineering.This paper brings forward the “T-type combined steel sheet pile” creatively on the background of the expansion project of Nanjing non-government school from the view of its environment benefit,economy benefit and safety. It guarantees the safety of foundation pit and provides construction space without inner support. This system combines supporting steel sheet pile and anchor pile through a special connected pile. It forms the whole from top to bottom and improves steel sheet pile's ability of withstanding bending deformation to reduce the use of inner support and provide open space inside the foundation pit construction. This paper studied the stable performance of the supporting system and provided new method and train of thought through the calculation of structure, numerical simulation analysis and field monitoring data. The main content of this paper is as follows:(1)Use the finite element numerical analysis method to model and analysis the stability of“T-type combined steel sheet pile” system.(2)Present the advantages and disadvantages of the support method through analyzing the deformation degree of foundation pit, construction cost and construction technology, compared with the “H-section steel + steel sheet pile” combined supporting structure in the same pit.(3)Use scientific and reasonable method of foundation pit monitoring to analysis deformation and displacement in the actual process of foundation pit supporting and the stability of the system through collecting, receiving and processing data.