Mesoscopic Numerical Simulation Of Taxial Test Of Geosynthetics-Aggregate-Clay Layered Reinforced Structure Based On PFC^3D

The“geosynthetics-aggregate-clay”layered reinforced structure can make use of the drainage function of aggregate and the good friction characteristics between geosynthetics and aggregate,thus it can significantly improve the geosynthetics-soil characteristics of reinforced clay structure when the moisture ratio increases,and ensure the long-term stability of the structure and promote the engineering application of viscous filler.In order to study the performance of the structure and the mechanism of the interaction between geosynthetics and soil,a series of numerical simulation models of layered reinforced structure were established based on three-dimensional particle flow code.The synergetic mechanism of geosynthetics,aggregate and clay was revealed by analyzing the macroscopic mechanical behavior of the reinforced soil and the evolution of mesoscopic parameters.The main work of this thesis includes the following two aspects:?1?A series of particle flow models based on triaxial test of layered reinforced structures were established by PFC^3D.The deformation and strength of layered specimens and layered reinforced specimens were compared,and the influence of layer number and laying thickness on the numerical results was also analyzed.The results of numerical simulation showed that laying aggregate in clay specimens can improve the post-peak strain softening and shrinkage-dilatancy characteristics,and the ductility and the peak strength of layered specimens can be improved by the laying of geosynthetics.The improvements reflected in the shear strength indices as an increase in the apparent cohesion of the layered specimens.On the contrary,increasing laying thickness has limited effect to improve the working behavior of layered reinforced specimens.?2?A series of particle flow models based on pullout test of layered reinforced structures were established by PFC^3D.The mechanism of interaction in geosynthetics-soil interface was analyzed on mesoscopic scale by monitoring the parameters such as displacement,contact force,coordination number and porosity of soil.Considering the laying thickness and compactness of aggregate as variables,the influences of the variables on the pullout test were studied on macro and micro scale.The numerical simulation results show that there are obvious differences in the movement trend and the micro-parameter variation of soil in different areas,and the parameter variation in the interface region exhibits asymmetrical feature.The laying of aggregate can significantly improve the ultimate pulling strength of the reinforced clay structure,but the ultimate pulling strength will not keep increasing with the increase of the laying thickness.In the range of normal stress selected in this thesis,the compactness of aggregate has little effect on the ultimate pulling strength.