Experimental And Numerical Simulation Study On Pullout Behavior Of Geogrid Under Clay

It is known that soil is good at compression resistance but bad at shear resistant.These characteristics make a huge limitation of soil's engineering applications.Therefore,laying geogrid in slopes and retaining walls is a new technology in geotechnical engineering recently which is developed quickly,now the design method of reinforced soil structure is also built on the theory of limiting equilibrium.In practical engineering,however,it is not perfect to get reinforcement effect in silty soil with geogrid,the reasons of which are that the drawing resistance between grid and silty soil is not enough and the strain of grid is so small to reach its limit, and a large relative displacement between grid and silty soil which causing the performance degradation of grid reinforcement.How to fully display the passive resistance of the cross rib in grid using its unique mesh structure is a problem worth deeply studying.The pulling action provided by grid belt is considered based on ordinary construction,but the facing wall of reinforced structural is neglected,which is proved by some studies to lead to conservative design,thus,the main content and success of study in this paper is shown as follows:Firstly,the history of geo-synthetics is reviewed,and the classes,engineering properties and reinforcement mechanics of geogrid are also introduced.Secondly,according to the principle of tensile test,research on tensile test of geogrids and red clay was made.Integrated consideration was made on different water content and vertical stress's effects to the frictional resistance characteristic between geogrids and clay during testing process.The results showed that:with the changes of water content,the relation between drawing force and displacement also changes.When the loads stopped,Re-distribution of stress will appears.Frictional resistance characteristic of geosynthetics in red clay are gotten by pullout test,It is value for pullout test and engineering application.Lastly,The relevant numerical analysis of drawing resistance was carried on.The data calculated and measured were compared.Discussed and analysed some parameters which effect the drawing force such as,the layer and the distance of the geogrids.It was showed that in the same pressure with the increase of the displacement,the drawing force of geogrids increase gradually,but when pulling up to a certain load value,the pull-out loads display more moderate growth.