Study On Soil Arching Between Adjacent Cantilever Stabilizing Piles And Calculation Method Of The Retaining Plate In Slope Engineering

Cantilever stabilizing pile is one of the traditional retaining structures in slope engineering.After the excavation of soil in front of the piles,concrete retaining plates are usually installed between adjacent piles to prevent the collapse of soil between piles.In order to investigate the design and calculation method of this kind of engineering structure,the soil arching effect between the adjacent piles and calculation method of earth pressure on the retaining plate are analyzed comprehensively in the dissertation.The main research results are as follows:(1)Based on the limit equilibrium theory and unified strength criterion,calculation formula for the reasonable pile spacing considering soil arching effect is derived.It is suggested to take the minimum net spacing at the bottom of the loading segment of the piles as the reasonable value.The reasonable net spacing is correlated negatively with landslide thrust and positively with the cohesion and internal friction angle of the slope soil,and it is more sensitive to the internal friction angle.(2)According to the theory of elasticity and principle of stress superposition,the distribution diagram of the maximum principal stress of the retained soil is obtained.It is determined that the distribution pattern of the soil arch in the horizontal plane is similar to the isosceles triangle.Besides,Drucker-Prager strength criterion is introduced to analyze the influence of intermediate principal stress on soil arching effect,and it is quantitatively revealed that the soil arch height decreases nonlinearly with depth.The general trend of the theoretical analysis is in good agreement with the three-dimensional numerical simulation results.The height of horizontal soil arch is positively correlated with pile spacing,pile width,the cohesion and internal friction angle,but the net pile spacing have major effect on it under the conditions of this study.(3)Soil arching effect between cantilever stabilizing piles is conducted via FLAC3 D.Taking the minimum displacement point of the soil mass in the direction of landslide thrust as the location of the soil arch axis,the relationship between the soil arch height with the depth is obtained.It is found that the soil arching effect is approximately uniformly distributed in the zone near the top of the pile,and it can be considered as the two-dimensional plane strain problem.The self-weight of the soil arch near the bottom of the loading segment of the pile has significant effect on the soil arching effect,which should be regarded as a three-dimensional problem.(4)Based on the analysis of soil arching effect of local collapse arch between piles,the reasonable spatial distribution pattern of earth pressure on the retaining plate is determined.It is isosceles triangle distribution in the horizontal direction and triangle distribution in the vertical direction.A three-dimensional plate model is proposed to analyze the stress and deformation of the retaining plate,which is simply supported on its two lateral sides by the piles and free on its upper and lower sides.The corresponding calculation formulas are derived.Also,the maximum bending moments in the two directions of each plate can be figured out,which provides a basis for the rational reinforcement design of the plate.The results of this dissertation can provide theoretical guidance and reference for the engineering design of cantilever stabilizing piles including the calculation of earth pressure and internal force of the retaining plate.