Numerical Analysis Of Double-row Pile-anchor Retaining Structure

With the development of economy and the popularity of high-rise and supper high-rise buildings, the depth of excavation of foundation ditch brings new challenges constantly for the design and construction of it. While the traditional means of single-form support means cannot meet the needs of the times gradually. Double-Row pile-anchor retaining structure is a new supporting technology, and the success of this support structure combines double piles and bolting, which can control soil and supporting structure deformation effectively, and it is suitable for the tight schedule and limited space of supporting structure especially. The double-row pile-anchor retaining structure research remains deficent, especially in the theory of its force and deformation research. Based on the basic theory of double-pile retaining structure, bolting structure, pile-anchor retaining structure, the double-row pile-anchor retaining structure has been analyzed. Meanwhile, Combined with practical engineering examples, using three-dimensional finite difference program FLAC3D software, to create a numerical model, and further establish the model of numerical simulations according to the program, from which some meaningful conclusions can be got, and then provides reference for similar projects. The main contents and results are as follows:(1) Summarizes the status of double-row pile retaining structure, bolting structure, pile-anchor retaining structure and the unique technical advantages of the double-row pile-anchor retaining structure. This thesis introduces double-row pile-anchor supporting structure theory analysis method and discusses the method of the structure of theoretical analysis and numerical analysis.(2) Based on the finite difference software FLAC3D, numerical model is established; based on an engineering example, the every-step excavation is obtained after pile displacement and bending moment diagram. After the excavation, the maximum horizontal displacement of retaining structure with double-row piles is located in the upper position in the depth of foundation pit excavation. Inflection point is located at the bottom, the maximum positive moment in the pile appears near the excavation depth of1/2, the maximum negative moment occurs near the insertion depth of1/3in the excavation face, and the bending moment near the pile end are generally small. Row spacing is an important parameter for the design of double piles, when row spacing is too small the uneven force is reasonable, when row spacing is too large the frame effect weakened, and when the row spacing is D=4d the supporting effect is the best.(3) Through numerical analysis system to study the effects of double-row pile-anchor retaining structure stability factors, including row spacing, crown beam stiffness, bolt inclination and other factors, and recommendations on the rationalization of the actual construction are made.