Study On Optimization Design Of Geogrid Reinforced Embankment Based On Finite Element Numerical Analysis

Geogrid reinforced steep embankment is a new type of subgrade structure.Compared with geogrid reinforced retaining wall,it has simple structure,low engineering cost and strong adaptability to slope deformation.At present,this structure has been applied to highway,water conservancy and other engineering fields,and achieved good results.The analysis of mechanical behavior of geogrid reinforced steep embankment has become a popular research topic.At present,the theoretical research on geogrid reinforced steep embankment is relatively backward,and the research on the dynamic response of geogrid reinforced steep embankment under the action of traffic load is also less,which affects the application and development of geogrid reinforced steep embankment in practical engineering.Based on the geogrid reinforced steep embankment project in Shawan section of Xinjiang S101 line,the finite element method is used to analyze the mechanical behavior of geogrid reinforced steep embankment.The static analysis of geogrid reinforced steep embankment is carried out,and the dynamic response of geogrid reinforced steep slope embankment under the action of traffic load is discussed.On the basis of numerical analysis,the optimal design of reinforced steep embankment is carried out,and some applicable conclusions are obtained,which provide reference for the optimal design of geogrid reinforced steep embankment.The main research results are as follows:(1)This paper reviews the application and development of reinforced soil,probes into the theoretical research status of reinforced soil,and summarizes the mechanism of action and structural design methods of reinforced soil.The existing problems are analyzed and the direction and contents of further research are obtained.(2)By using Midas GTS NX finite element software and relying on the test section of reinforced embankment,the numerical simulation was compared with the measured geogrid strain value to verify the reliability of the numerical model.The potential slip surface,horizontal displacement and stress of the reinforcement are analyzed.The results show that the geogrid reinforced structure can make the potential slip crack surface of the embankment move inward.The geogrid reinforcement can effectively limit the horizontal displacement of embankment.The middle and lower area of embankment become the main stress area of geogrid.The geogrid reinforcement can significantly improve the overall stability of embankment structure.(3)Through the establishment of a three-dimensional numerical model,the vehicle load is simplified to the moving load,and the mechanical response of the embankment under traffic load is studied from the two aspects of stress and deformation of the reinforced steep embankment.The results show that:under the action of driving load,the dynamic response at the center of embankment is the most obvious,and the settlement and horizontal displacement deformation at the top of roadbed are the largest.Within the working area of roadbed,the geogrid near the road surface is under great stress.The variation trend of vertical stress,settlement and horizontal displacement of embankment at different depth is roughly the same under different vehicle loads.At different speeds,the settlement,horizontal displacement and vertical stress response curves of the embankment have inflection points,and the curves tend to decrease first and then increase.The reinforcement can effectively reduce the fatigue damage of embankment caused by vertical stress caused by driving load.(4)On the basis of the above theoretical research results,the influence of various parameters on the stability of the reinforced embankment was analyzed by changing the slope rate,soil filling cohesion,soil filling internal friction angle,bar spacing,elastic modulus of bar and slope grading method.The results show that the greater the angle of internal friction of the soil,the cohesive stress of the filling and the elastic modulus of the geogrid,the smaller the maximum horizontal displacement of the reinforced embankment and the better the overall stability of the reinforced embankment.Compared with the "middle dense" and "uniform" type,the "upper sparse and lower dense" type can effectively limit the horizontal displacement of embankment.For the steep slope embankment,the embankment can be strengthened by the form of embankment classification.In the design of reinforced steep slope embankment,it is suggested that the elastic modulus of geogrid should not be less than 7Mpa and the spacing between layers of reinforcement should not be more than 60 cm.