The Effect Of Particle Arrangement On The Macro-mechanical Properties Of Sandy Soil

The soil structure will directly affect the mechanical properties of the soil,and exploring the influence of the soil structure on the macro-mechanical properties of the soil is conducive to the establishment of a constitutive model containing soil structural parameters.The shape and arrangement of soil particles and the connection between particles will affect the soil structure.In this paper,the effects of particle size and particle arrangement on the macro-mechanical properties of sandy soil were investigated.The main research results are as follows:(1)Through the numerical simulation of the sandy soil laboratory tests of 5 different grain groups,combined with the contact force chain diagram of the particles,the displacement field and the velocity field;the mesoscopic analysis of the shearing change of the sandy soil under different grain groups is explored.The research shows that:the smaller the particle size is,the more uniform the force chain network is,and the finer the skeleton force chain of the particle will lead to poor stability,so the peak deviatoric stress is lower;the larger the particle size,the sparser the force chain network,However,the interaction between particles becomes more obvious,and it is easier to form an effective way of transmitting force,which corresponds to its higher peak deviatoric stress.(2)Based on discrete element software,the influence of various mesoscopic parameters(friction coefficient,anti-rotation coefficient and particle normal contact stiffness)on the peak deviatoric stress of a single particle group sample was analyzed.The research shows that:under the same friction coefficient,anti-rotation coefficient or normal contact stiffness,with the increase of particle size,the peak deviatoric stress of sand samples also increases.Under the same confining pressure,the larger the particle size is,the larger the peak deviatoric stress of the sample is;with the increase of particle size,the friction coefficient,anti-rotation coefficient or normal contact stiffness affect the peak deviatoric stress of the sample more pronounced.With the increase of friction coefficient or anti-rotation coefficient of each grain small,but with the increase of friction coefficient or anti-rotation coefficient under high confining pressure,the increase of peak deviatoric stress of the specimen is larger.(3)Based on the division of particle groups,numerical simulations were carried out on sandy soil experiments with four different arrangements,combined with the contact structure,coordination number,contact force chain diagram,displacement field and velocity field of the particle system.To explore the mesoscopic analysis of the shearing change of sand with different particle arrangements.The research results show that the direction of particle contact force tends to be distributed vertically in the initial state of arrangement sample 1 and arrangement sample 4.As the shear strain increases,the force chain network becomes denser and more particles begin to participate in the transfer of stress,increasing the effective contact between soil particles to resist external loads.After loading,a relatively stable force chain network is formed inside the sample.In the process of shearing and compression,the samples in each arrangement mainly show that the large particles compress each other first,and the small particles move around to provide lateral support.(4)Based on discrete element software,the influence of various mesoscopic parameters(friction coefficient,anti-rotation coefficient and particle normal contact stiffness)on the peak deviatoric stress of each arrayed sample was analyzed.The research shows that:with the increase of friction coefficient,the increment of the peak deviatoric stress of arrangement sample 1 and arrangement sample 2 is the largest;with the increase of the friction coefficient,the increments of the peak deviatoric stress of the arrangement sample 3 and the arrangement sample 4 are relatively small.At 100kPa,the anti-rotation coefficient has the greatest influence on the peak deviatoric stress of the arrangement sample 1;at 200kPa and 400kPa,the anti-rotation coefficient has the greatest influence on the peak deviatoric stress of the arrangement sample 4.With the increase of the anti-rotation coefficient,the increase of the peak deviatoric stress of the arrangement sample 3 is the largest.The samples with different arrangements all show that the peak deviatoric stress of the samples increases with the increase of friction coefficient or anti-rotation coefficient.