Numerical Simulation Of Double Row Rile Retaining Structure In Deep Doundation Pit Engineering

With the development of buildings,there are new changes in t he form of foundation pit supporting.Double row piles supporting structure has great resistance to overturning because of the role of connected beam.It has excellent performance in deep foundation pit supporting project.so it has been widely applied in recent years.However,because of the late development,there are no more mature norms in the theoretical calculation of the double row pile supporting structure and the analysis of the influence factors.Based on the background of engineering practice and previous studies,by using theoretical analys,a numerical simulation software MIDSA/GTS NX is used to calculate and analyze the foundation excavation of double row piles supporting structure.The main conclusions are as follows:1.In the process of double row pile foundation excavation,with the continuous increase of the excavation depth,the uplift of the middle of the foundation pit is also increasing,and the settlement value around the foundation pit is getting larger and larger,and the spatial effect is becoming more and more obvious.The coupling beam of double row piles can restrain the deformation of the pile top and redistribute the bending moment for the pile body,so that it can play a supporting role better.2.In the comparison of two row piles with different row spacing,it can be shown that the distance between front and back row piles continuously decreases with the increase of the distance,but the trend of the continuous decrease becomes more slow as the distance becomes larger.3.With the increase of the distance between front and back row piles,the displacement of front and back row piles continues to decrease and gradually becomes stable.Shortening the front or back row piles will cause the displacement of pile top to increase,and the increase of pile top displacement will speed up.Comparatively speaking,the change of pile length of front row piles is greater than that of the back row piles for the double row piles.4.When the pile diameter increases,the bending moment increases,and the rate of increase increases,but the displacement and velocity of the front and back piles decrease.Increasing the pile diameter within a certain value range can reduce the displacement of the front and back row piles.5.Strengthening soils between piles can reduce the maximum displacement of soil outside the foundation pit,but when the soil stiffness reaches a certain value,the trend of the maximum displacement of the soil outside the foundation pit will gradually decrease.6.Based on the design of single row piles,it is suggested that the displacement of front and back row piles should be 2.4m.The length of piles in the back row remains unchanged,and the length of the front piles is 15.5m.Pile diameter remains unchanged.Soils between piles is reinforced by cement-soil mixing pile.