Research On Slope Stability Analysis And Its External Buttressed Reinforcement Structure For Balance Weight Retaining Wall In Operating Mountainous Expressway

Aiming at the potential instability of the soil embankment slope and the active retaining wall of the operating expressway in the mountainous area,and relying on the embankment slope maintenance engineering of K765+300～K765+500 up direction of Yue-Qian Section in G35 Ji-Guang Expressway in Anhui Province,and puts forward the reinforcement scheme for the potential instability slope and carries out the stability analysis,so as to provide reasonable guidance and reference for the maintenance and prevention of slope stability based on the project.1)Embankment filler is sandy soil SW with good engineering properties.Through the preparation of soil samples with four compaction degrees and five moisture contents,indoor large-scale direct shear test and portable drop weight deflectometer(PFWD)test are carried out.The results show that increasing compactness and vertical pressure can improve shear strength and its parameters.Increasing the moisture content will increase the shear strength and cohesion first and then decrease,while the internal friction angle will always decrease.The elastic modulus increases with the increase of compaction degree and decreases with the increase of water content,and the influence of compaction degree on elastic modulus is more significant.Accordingly,through regression analysis,the relationship between internal friction angle,cohesion and elastic modulus and water content and compaction degree was established,and the prediction models of shear strength parameters and elastic modulus based on water content and compaction degree were obtained.2)FLAC3D finite difference software is used to analyze the sensitivity of soil moisture content and compactness to the influence of the slope stability of the counterweight retaining wall based on the project.The results show that the slope safety factor and the stability coefficient of the retaining wall increase first and then decrease with the increase of moisture content under the same compactness,and increase with the increase of compactness under the same moisture content.The change of moisture content and compactness is more sensitive to the influence of the stability coefficient of the retaining wall.The slope is in a stable state,and the anti-slip stability coefficient of the retaining wall is less than 1.3 when the water content is large,which does not meet the stability requirements.It is necessary to consider the reinforcement of the retaining wall.3)Using FLAC3D software to analyze the slope stability under the most unfavorable conditions,the safety factor is 1.02,and there is a risk of instability;Based on this,the reinforcement scheme of retaining wall with steel pipe reinforcement of waste guardrail column outside the retaining wall is proposed.By selecting the geometric parameters of different reinforcement structures,the numerical simulation of retaining wall stress and slope stability is carried out.The results show that reducing the spacing of retaining wall,increasing the thickness of retaining wall and the length of steel pipe can increase the safety factor,so as to determine the optimal spacing of retaining wall 5.5 m,the thickness of retaining wall 1.5 m and the length of steel pipe 3.5 m.