Numerical Analysis Of Two-stage Anti-slide Pile Reinforcement For The Long Fissure Cutting Slope Of Nan Yi Expressway

The unstability and deformation of the slope will sometime affect the construction schedule,quality and operational safety of the project,but it will also cause heavy casualties and major losses to the national economy.At present,the stability analysis of soil slopes mainly considers the influence of deterministic weak interlayer,and ignores the effect of fractured structural planes,especially the effect of long fractured structural planes.There are a large number of random fissure structural planes in soil slopes.These fissure structural planes have long spans ranging from several centimeters to dozens of meters,and their stiffness and strength are much smaller than the surrounding soil,and this will affect the slopes stability.Therefore,it is of great practical significance to study the reinforcement mechanism of anti-sliding piles in landslip landslides with long cracked structures.Based on the subgrade engineering of the Nanyi Expressway,this paper uses the finite element strength reduction method to simulate the three-dimensional elastoplastic analysis of the landslide mechanism of the cutting soil slope.It is proposed to construct two kinds of piles in the form of anti-slide pile reinforcement slope scheme.One is the rectangle arrangement of two stage anti-slide piles and the other is the diamond arrangement of two stage anti-slide piles.The two supporting modes are numerically simulated and compared.The main research work and research results of this paper are as follows:(1)According to the field excavation of K42+535?K42+765 section of Nanyi Expressway,the location of the weak sandwich was determined,and the long cracked structural plane with a length of 4m or more was counted.The morphological parameters of the long cracked structural plane were analyzed.Based on the distribution law in the slope soil,a lot of long cracked structural planes were randomly generated in the computer.(2)Simulation software was used to simulate the dry-wet cycle of the slope soil according to the local hydrogeological conditions,and combined with the actual survey report of engineering geology,the physical and mechanical parameters of the soil in the shallow surface region were obtained.Then,combining the finite element numerical simulation method,the calculated parameters of the long cracked structural planes,the weak interlayer calculation parameters and the calculated parameters of each soil layer were used as the finite element numerical simulation parameters of the slope to analyze the slump mechanism of soil slope with long cracked structure surface,which was concluded that the soil slopes with long cracked structural plane and weak interlayer had more obvious instability failure.(3)According to the pile diameter and pile distance provided by the survey design report,the pile type was selected,combined with the sliding surface of the slope,the better pile position was selected,and the finite element numerical simulation was used to compare and analyze the two different piles in the same spacing.The schemes mainly considered the horizontal displacement,plastic strain,pile displacement,pile shearing force,soil slope safety factor and soil arching effect of the slope soil.It was concluded that the two-stage anti-slide pile shape arrangement had better slope reinforcement effect than the rectangular arrangement in the pile body deformation and soil arching effect which was more in line with tbe actual engineering.