Research On The Stability Of A Two-tier Reinforced Soil Structure Without An Offset Under The Seismic Load

China has a large land area and a wide distribution of seismic zones.The mountainous and seismic geological conditions have brought about the problem of slope instability that can not be avoided.In order to solve this problem,reinforced soil structure can be used for reinforcement.At present,there are many kinds of retaining structures,among which reinforced soil structure is widely used in China because of its good seismic performance.In recent years,there are more and more theoretical research and engineering practice of reinforced soil structure.From single-stage reinforced soil structure to double-stage reinforced soil structure,even multi-stage reinforced soil structure has been applied in engineering practice.In this paper,a new type of reinforced soil structure,two-tier reinforced soil structure without an offset,is studied.This structure not only has the advantages of double step reinforced soil structure,but also avoids the trouble of step setting,and can save filler,and is also convenient for greening treatment.Based on the principle of limit equilibrium,the internal and external stability analysis method of two-tier reinforced soil structure without an offset under seismic load is established in this paper.First of all,the internal stability analysis considers the influence factors such as the dip angle of the lower structure,the cohesive force of the filler,the depth of the tension crack,etc.,analyzes the change of the tensile coefficient of the upper and lower reinforcement materials with the change of the seismic load,and discusses the influence of the dip angle of the lower structure,the cohesive force of the filler,the depth of the tension crack and the seismic load on the critical sliding surface;then,the external stability considers the horizontal sliding failure This paper analyzes the relationship between the safety factors of the three failure modes under the influence of the ratio of the height of the upper structure to the total height,the dip angle of the lower structure,the distribution form of the reinforcement and the earthquake load.Finally,an example is given to show the application process of the research method in the seismic design of two-stage stepped reinforced soil structure.