A Study On The Interaction Mechanism And Stability Of Geogrid Reinforced Soil Steep Slope With Wrapped Face

Rencently,as the reinforced soil technic getting widely used,scholars from domestics and foreign countries have done a lot of research on the structural characteristics of reinforced soil.Due to the complexity of characteristics of rock and soil as well as the engineering practice,the current findings still can not meet the needs of engineering practice.Currently,the research on the reinforced soil with wrapped face is focused on single-stage or multi-level upright shoulder reinforced soil retaining wall,the filling material is mostly clay or sand.However,there are only few studies on reinforced soil steep slope structures and gravel soil fillings.Addtionally,there are insufficien researches or inderstandings oninteraction mechanisms between soil and reinforced material as well as the influence factors of the stability and the deformation mode of the reinforced soil structure.Due to the aforementioned reasons,the paper is based on a geogrid reinforced soil steep slope of up to 22m in the southwest mountainous area,and systematically studied the key issueses such as the structural load state,the relationship between soil and reinforced material,the influence factors of the stability and the deformation mode of the reinforced soil structure.The outcomes of the research can provide theoretical basis for the design and construction of similar reinforced embankment structure,and haveimportant engineering application value.Work and findings from the current study are shown as follows:1.Through the interface shear test of coarse-grained soil and geogrid,the interaction between rib and soil interface is revealed.The main results include:as water content increases,the friction angle of the interface reduces gradually,but the cohesion increases first and then decreases;a positive correlation between the coarse particle content and the interfacice shear parameters was found;The reinfocement can obviously improve the cohesion of the soil,however,the friction angle decreases.2.An site monitoring test was carried out on geogrid reinforced soil steep slope with wrapped face.The structural load state and the potential fracture surface of the reinforcement were analyzed.The main findings include:reinforced soils can effectively improve the stress distribution in the soil and reduce the vertical pressure of the base;the stress state inside reinforcement body is re-adjusted at a later stage,resulting in reduced grid strain;for this flexible return-type reinforced soil structure,due to the limited deformation,the longterm slope deformation will still be under development;the potential rupture surface of the stiffened body is circular.3.The numerical analysis model of different operating conditions was established by using FIAC3D.The reinforcement mechanism,stability factors,deformation and failure characteristics of geogrid reinforced soil steep slope with wrapped face are discussed.The main results include:laying the geogrid in the roadbed can significantly reduce the lateral deformation of the roadbed;the lateral deformation of the subgrade under each condition shows obvious bulging characteristics;reinforcement can improve the distribution of shear strength;the embankment slope has a significant effect on the tensial state of the geogrid.4.Based on the results of field monitoring and numerical simulation,the centrifuge model under different working conditions was established.The influence factors of the stability,the distribution characteristics of soil stress and reinforcement material strain and the deformation process of the reinforced soilwere studied which further verified the reliability of the relevant conclusions.The main results include:in steady state,the potential microcracks inside the reinforced soil structurewere not developed along the standard arc,straight line or fold line,but influenced by the reinforcement and the soil contact surface,which presenting a complex distribution form;by assuming the potential rupture inside the reinforced slope is arc-shaped,thedetermination of the arrangement parameters of the reinforced material by searching the position of the most dangerous rupture plane is reasonable;the location of 0.3H rupture surface of the upright reinforced embankment cannot be determined only by the method of non-reinforcement subgrade based on the wall height and the soil friction angle.The determination of the most dangerous rupture surface position should combine the effect of reinforcement with the results of numerical simulation.