Numerical Simulation Of Double-Row Piles Structure

Retaining structure with double-row piles as a relatively new type of supporting system, with high resistance to lateral stiffness, deeper supporting depth and wide working face, save the cost and other advantages. It can simplify the construction process effectively, improve the convenient of the construction, accelerate the construction progress, convenient earthwork excavation, improve engineering benefit, especially in the deep pit and high slope engineering, the comprehensive advantages of double-row pile retaining structure is more prominent, and gradually become one of the optimization scheme, The compound itself and two element assemblage characteristics of pile and soil make its stress and calculation mode more complexer. Its design and calculation theory is far from perfect, practice leading in some aspects and theory lags behind. At present, no matter from the theoretical calculation, structure design, to the engineering practice, especially the mechanical mechanism, working properties and the suitable conditions are still constantly explore and improve. This paper is more system and further research study on the basis of the previous research results on the retaining structure with double-row piles. The main work and achievements are as follows:(1) Achievement of retaining structure with double-row piles is studied in the large general finite element software MARC implementation. How to establish the calculation model, including geometry model, constitutive model, boundary conditions are described, the parameter such as pile, soil, contact analysis are selected to determine the numerical simulation(2) Establish a MARC finite element calculation model of retaining structure with double-row piles and operations on the finite element software MARC, come to the related finite element calculation results and the cloud images; The variation characteristics of soil displacement was obtained through Simulation results for the numerical simulation analysis, and the stability of the double-row piles were simulated evaluation shows that the structure of double-row piles MARC numerical analysis is feasible.(3) To study the soil parameter change on the influence of retaining structure with double-row piles. In the soil parameters, the effect degree of elastic modulus and Poisson’s ratio is larger than cohesive force and Angle of internal friction on deformation of the supporting structure. The effect to control double-pile horizontal displacement effect by reinforcement passive zone is significant, and there is an optimal reinforcement dimensions. The effect through reinforcing soil between the piles is not obvious, but it can make the pile bending moment fell dramatically. Influence of ground overload factor on the stability of foundation pit is relatively large. When the excavation size increases, double row pile top displacement increases.(4) The effects of parameter changes on the double-row pile supporting structure. The row spacing has a significant impact on the performance of double-row piles retaining structure. It can reduce the horizontal displacement of the pile by increasing pile stiffness, connecting beam stiffness of pile, but generally decreases the amplitude is smaller, the effects of control pile-soil deformation is very limited. At the same time, the increasing of pile stiffness and connecting beam stiffness of pile will make the internal forces of pile. Increase pile embedded depth can make the value of the horizontal displacement of the pile reduced, but to a certain value, but to a certain value, the growth of small and basically unchanged, there is embedded depth has a relatively optimal value of embedded depth.(5) Combined with Technical Specification for Retaining and Protection of Building Foundation Excavations, The theoretical source of the calculation model about the double row piles used in the specification are analyzed and Based on this, such as the earth pressure calculation method, the initial earth pressure distribution between pile, boundary conditions of the calculating model about double row pile yet to be perfect in the specification are discussed.(6) The calculation model of this paper is verified the repeatability, feasibility and rationality through the comparative analysis of the numerical simulation results.