Stability Analysis Of Muti-level Retaining Structure In High Fill Slope

With the rapid development of modern construction,land resources become more and more tense.People use the limited ground to build a variety of high-rise buildings,water and hydroelectric facilities,ports and railways,and many other projects.During the construction of these projects or the operation period after their completion,a large number of slope projects are inevitably formed,which will inevitably bring about the problem of slope stability.At present,there are many studies on the stability and deformation analysis of simple slopes.However,the stability analysis of multi-level retaining structure of artificial slopes needs to be further improved.Therefore,the research on the stability of permanent multi-level retaining structure in high fill slope has important theoretical and practical significance.Based on the two-stage slope engineering of the west side of Hongrun city of Sanmenxia,this paper adopts the finite difference software FLAC3D and establishes the numerical analysis model to simulate the stability of the permanent slope under different supporting structures.The main research contents and conclusions are as follows:(1)The actual construction conditions,support requirements,and the finite difference method numerical simulation analysis method of existing fill and subsequent fill of the engineering site are introduced.The existing fills have been developed for passive reinforcement.And follow-up fills have been developed with active support for secondary support.(2)The undisturbed soil slope was reinforced with soil nails.Two-step follow-up fill slope used buttress wall retaining scheme.A numerical analysis model was established to simulate and analyze the development law of slope plastic zone distribution,maximum shear strain increment,slope displacement,and overall safety factor of the slope with subsequent layered filling.The results showed that:After using 5 rows of soil nails in a first-grade slope,its deformation behavior was stable.However,the vertical settlement of the secondary slope was larger.The slope forms a sliding surface along the deep soil as a whole,and the overall stability safety factor F_s is less than 1.3,which does not meet the requirements of the Technical code for building slope engineering(GB50330-2013).(3)The primary soil slope is not supported.The secondary slope adopts multi-row pile and buttress retaining wall support scheme.A numerical analysis model for multi-stage supporting slopes is established to simulate and analyze the plastic zone distribution,the maximum shear strain increment,the slope displacement,and the overall safety factor of the slope.The results showed that:After the multi-row piles with buttress wall retaining scheme were adopted for the second-grade slope,its position and deformation behavior was stable.For the unsupported part of the first-order slope,the plastic zone appeared at the foot of the slope,forming a slip surface.The overall stability of slope safety factor F_s is less than 1.3 and does not meet the requirements of the Technical code for building slope engineering(GB50330-2013).(4)The primary fill slopes have been reinforced with soil nails.The second-level follow-up fill slope adopts the supporting plan of multi-row piles with buttress retaining walls.A numerical analysis model for multi-level retaining slopes is establish to simulate and analyze the development and change law of axial force of axial nail,axial force of pile body,shear force and bending moment of pile body as well as slope displacement,safety coefficient of overall stability in the process of layered construction.The results showed that:The horizontal load formed by the layered filling of the secondary slope into the soil was partly transmitted to the anti-sliding multi-row piles and the reinforced soil nail supporting members.It caused the pile to produce the bending moment and the shear force,and it caused the soil nail to produce the axial force;Fills the soil to form the vertical load part to pass down through the multi-row pile.The vertical load formed by filling the soil was transmitted downwards through multiple rows of piles,so that the plastic zone of the slope developed deep into the soil,eventually forming a slip surface around the soil nail and the multi-row pile supporting area.The overall stability safety factor F_s of the slope is greater than 1.3,which satisfies the Technical code for building slope engineering(GB50330-2013).It is reasonable and feasible to prove that the multi-level slopes adopt the combination of soil nailing reinforcement and multi-row piles with buttress wall retaining scheme.Various supporting forms have played their respective roles well and the overall slope is in a stable state.