Stability Analysis Of Soil-rock Dual Structure Slope Reinforced By H-type Anti-slide Pile

Soil-rock binary structure slopes are widely distributed in the western area of our country,where large and medium-sized landslides occur frequently,posing a serious threat to human life and property safety.Experts found that using ordinary single pile to support in this area requires a large pile length,which is easy to lead to pile instability.Based on this,h-type anti-slide pile with high stability has come into people’s vision.As a new type of anti-slide pile,the research on it has not received enough attention.Therefore,this paper takes the typical soil-rock binary structure slope as the object,adopts the three-dimensional numerical analysis method to conduct an in-depth study on the reinforcement effect and mechanical response of h-type anti-slide pile with different slope morphology and different pile location,and optimizes the supporting parameters of h-type anti-slide pile.The main research work and achievements are as follows:(1)Establishment and verification of 3D numerical analysis model.Based on the typical soil-rock binary structure slope,a three-dimensional numerical analysis model of slope-pile is established to study the effects of model size and grid size on the safety factor of slope,potential sliding surface and slope top displacement,and the numerical results are compared with the classical slope model for verification.The results show that the rationality and reliability of the numerical analysis model can be guaranteed when the width of the slope top,the width of the slope bottom and the model height at the slope bottom are respectively taken as 35 m,30 m and 35 m,and the grid size is 2 m×2 m.(2)Comparative study on strengthening effect of h-type anti-slide pile under different slope morphology.Based on Rhino drawing software and FLAC3 D finite difference software,a three-dimensional numerical analysis model of slope-pile with different slope morphology and pile position is constructed,and the reinforcement effect and mechanical characteristics of h-type anti-slide pile are thoroughly studied.The results show that the h-type anti-slide pile is more suitable for convex slope,and when the horizontal length of the rear pile from the slope foot is 1/4 of the slope length,the soil thrust and anchorage depth reach the optimal balance point,and the reinforcement effect is better.The reinforcement effect of h-type anti-slide pile increases with the decrease of curvature radius of convex slope when the pile body changes in flexure,but the law is opposite for concave slope.As the anti-slide pile moves to the foot of slope,the anchorage depth increases gradually and the stability of the anti-slide pile is enhanced.(3)Optimization analysis of h-type anti-slide pile.Designing an orthogonal test and conducting parameter significance analysis by calculating the extreme difference and variance to obtain the important factors affecting the reinforcement effect of h-type anti-slide piles.Keeping the total length of h-type anti-slide pile constant,change the length of front pile,back pile and connecting beam to study the optimal pile shape of h-type anti-slide pile.The results show that the significance of each factor in descending order is: anchorage depth of front pile,anchorage depth of rear pile,length of connecting beam,distance between piles;When the total length of anti-slide pile is large,the optimal pile type is "h" at the same horizontal plane of the front and rear pile bottom.When the total length of anti-slide pile is small,the optimal pile type is "h" when the rear pile bottom is higher than the front pile bottom.The optimal change value is significantly affected by soil parameters,slope angle and total pile length.