Optimization Design On The Retaining System For Loess Foundation With Double-Row Piles

This article summarizes the research status in the characteristics and arrangement of the double-row piles retaining system, analyze several calculation models about this retaining system and put forward their applicable conditions and limitations.At present, the use of double row pile retaining system are mainly concentrated in the eastern coastal areas, but seldom used in the loess area of West China. This article tends to study the suitable application of double-row piles retaining system in deep foundation pit. Based on this, the article uses the finite element software ABAQUS to establish the finite element model of retaining structure with double-row piles, and to analyze the effect of row spacing, the pile section size, concrete strength and the pile length on the pile displacement and bending moment. As a contrast, the retaining structure with single-row pile is compared with the double-row piles under the same foundation condition.The research results show that:(1) The double-row piles has more advantages than the single-row pile in aspect of safety performance in loess foundation pit of our country.(2) Row spacing of double row piles has a greater influence on the deformation and internal force of the retaining system. Considering the factors of safety, the row spacing of double row piles in retaining system for loess foundation pit is selected as a 2D～5D, or 1.6m～4.0m.(3) Section size of piles has a certain influence on the deformation and internal force of the retaining system. Comprehensive considering the factors, such as safety, economy and so on, the section size of double row piles retaining system in loess foundation pit is advisable to choose between 0.6 m to 1.0 m.(4) Pile concrete strength has a little influence on the deformation and internal force of the retaining system. But considering the safety, economic factors, the concrete of double row piles retaining system in loess foundation pit is advisable to choose the C20, C25 and C30.(5) In meet request of minimum embedded depth, simulation study shows that, the pile length of double row piles retaining system in loess foundation pit is advisable to design between 1.9 H to 2.5 H (H is the depth of foundation pit).(6) In meet request of minimum embedded depth, through simulation the different length of front and rear row pile of the retaining system for the influence of deformation and internal force, by increasing the length of the front and rear row pile can effectively increase the overall stability of retaining system, and increase the rear row pile length on the influence of the retaining system is more obvious.