Research On The Mechanical Features Of Double-Row Anti-Slide Piles With Tops Exposed Or Embedded In Bedrock-Overburden Landslide Control

Double-row anti-slide piles which are tops exposed and embedded as an effective anti-slide structure have gradually been applied in sliding slope of strengthening and governance. Because the mechanism of the interaction between the soil and the pre-piles and post-piles is very complex, in addition,various factors affecting to the force of piles are not entirely clear, the design and application of double-row anti-slide piles with tops exposed and embedded are still studied, not yet mature theory and design. This paper systematily studise force characteristics of double-row anti-slide piles with tops exposed and embedded by finite element method and large-scale model test indoor, with analysing the row spacing, buried depth, pile-soil friction and other factors what impact on force and deformation of piles. The major content is followed:(1) Auther establishes the approximate limits equilibrium of algorithms by simplifying the form of resistance distribution of double-row anti-slide piles on the base of the limit equilibrium theory.(2) The recent status of double-row anti-slide piles and all kinds of analysis and calculation method are summed up.And auther simplifies the form of resistance distribution of double-row anti-slide piles:resistance of pre-piles distributes by triangle,and resistance of post-piles distributes by rectangle. In addition, limit equilibrium theory of the piles is Improved.(3)The author studies the relationship between piles reasonable spacing and cross-section height H under different dip of slip surface:The reasonable row spacing is between 13h-17h when the dip of slip surface is 15.2°; between17h-23h when the dip of slip surface is 17.6°; between 23h-27h when the dip of slip surface is 20.6°; between 26h-30h when the dip of slip surface is 24.0°;and summarizes relationship between reasonable spacing and dip of slip surface, sliding body stiffness, sliding bearing section thickness and pile length as H= 3.92*ρ+24.8. Moreover, author analysises effect on distribution of the force of piles in changing the slip surface angle and pile spacing.(4)Through analysis of finite element model of different pile peak buried depth, reasonable buried depth of double row anti-slide piles with embedded is concluded,the proportion of reasonable buriedζ= 0.2-0.3 is proposed.As the buried depth is increased, the form of distribution of pushing force of landslide and resistance of post-pile become rectangle distribution; pushing force of landslide and resistance of pre-piles distributes are basically invariant.(5)A pile-soil interface unit cell is established in a finite element model; through changes of interface unit parameter, influences of friction between pile-soil on stress discipline of a pile body is analyzed. The study shows that friction between pile-soil can reduce pushing force of landslide on pile body, increase resisting force of slope in front of a pile, and contribute to reducing the bending moment of pile.(6)Through comprehensive comparison and analysis of double-row anti-slide piles with tops exposed and embedded.The results show that adoption of double-row anti-slide piles with embedded can reduce stress of the pile body, lower the bending moment of pile, reduces reinforcing bars and concrete dosage of the pile body; the structure is an economical and reasonable anti-slide structure, and is worthy to be applied and promoted.