Mesoscopic Mechanism Study Of Interface Interaction On Soil And Geosynthetics

Application of geosynthetic materials can effectively solve the problem ofengineering slope stability, settlement deformation etc. The research of reinforced soilstructure is given priority to indoor model test and field test while most of theseexperiments of reinforcement mechanism are from the macroscopic perspective. Due tothe complexity of reinforced soil effect, the research on reinforcement mechanism is notthorough enough that limits the development of the reinforcement technology. Based onpredecessors’ indoor tests, this paper aims to reveal the microscopic mechanism of soiland geocell interaction of reinforced soil in the processing of drawing and triaxial tests,adopting the discrete element PFC to study the displacement developing rule and theinteract mechanism between soil and geocell from the microscopic perspective. This studyhelps to further enhance the understanding of reinforced soil interaction, and also providesreference for engineering design and disease treatment.On the basis of the indoor drawing test of standard sand and geosynthetic materials,we established simulation models of reinforced soil drawing test of PFC3D particle flow,analyzed both macro and micro regulation of drawing stress, displacement, soil porosity,contact number, and geocell stress-strain in the process of drawing, and revealed themicroscopic mechanism of the interaction of sandy soil and geocell. During the drawingprocess, from macro view, geocell is forced by the front to the back in turn along thedrawing direction; meanwhile, geocell nodes at the parallel drawing direction are mainlyaffected by drawing force, and geocell nodes at the vertical drawing direction are mainlyaffected by bending moment. From micro view, in the model container, soil moves to thedrawing direction as a whole; meanwhile, the soil porosity in the front gets smaller whilesoil stress and contact number gets bigger, but all the parametric variations in the back arein contrast to the front.At the same time, we studied the effect of different geocell hole size and height ofon drawing test results. Result show that the lager the geocell hole is, the more thetransverse ribs is suffering from bending moment and the stronger the drawingdisplacement needs to reach the peak, consequently the greater the force peak the geocellnode is suffering along drawing direction and the stronger the drawing displacement needsto reach the peak. However, when the soil stress value is decreasing, the relative value ofdrawing replacement is increasing. Moreover, the higher the geocell is, the smaller thebending value for traverse ribs is, and there is no obvious change for relative drawingreplacement. But when the force valve of the soil gets smaller, the corresponding peakdisplacement gets bigger.Based on the indoor triaxial test, we established simulation models of reinforced soildrawing test of PFC3D particle flow, studied the influence of different confining pressure,reinforced layer and geocell height on the experiment result. Results show that the greaterthe confining pressure is, the more the reinforced layers are and the higher the reinforced material is, the greater the limit value of deviatoric stress is, and the larger the soil requiresfor deviatoric stress to reach the same value for the same axial strain. By contrary, whenthe same deviatoric stress of soil axial strain gets smaller, the internal friction of soil getsincreasing.Through numerical simulation drawing and triaxial test simulation and varioussimulation analysis under different conditions, we studied a variety of macro andmicroscopic parameters regularity which could be accomplished in previous laboratorytests, we deepened the understanding of the mechanism of interaction between soil andgeocell. Moreover, we developed a new way of thing for later more reinforced soilmicrostructure research, analysis of practical engineering application of reinforced soil,and r design research of reinforced material parameters.