| With the further solidification of city construction pattern,the new pit is affected by site environment and surrounding environment.Thus the form of foundation pit supporting structure is greatly restricted.As a new type of retaining structure,double new piles are applied into practice more frequently.It is a portal space structure formed by connecting the pile of top beam before and after two rows.The structure has a larger lateral stiffness and can effectively limit the deformation of supporting structure and displacement etc.But the study of double row piles retaining mechanism is relatively few.And currently,we tend to adopt the same length of before and after the pile of double row piles retaining structure,which leads us to think about whether can we get a more economical and reasonable supporting structure of the double row piles by changing the length of the front and back pile.Based on the study of the length of portal double row piles,the article aims at exploring a new portal unequal structure of double row piles.Through the summarization of the currently common double row piles calculation model and the design calculation theory,we explore the rationality of the new portal double row piles,the limit supporting force under different rejection,pile length difference and other factors,pile top horizontal displacement curve and bending moment of the piles and the earth pressure by indoor model test.The test results show that this structure is more favorable for improving the limited supporting force of the portal double row piles and limiting the horizontal displacement of piles.As the front pile bears more pile internal force,so in the project,we can make the front pile thick and the back pile slim to adjust the distribution of internal force and make the stress of the front pile and the back pile equal,so that we can let the front pile and the back pile work together.The effect ismore obvious when the rowing spacing is in the range of 4D-6D and pile length difference in the range of 4D-5D.So that we can get a more economic and reasonable distribution structure of the new portal unequal double row pile to guide the engineering practice. |
