Research On Discrete Element Numerical Simulation Of Cohesive Soil Based On Cohesive Particle Contact Model

The macro-mechanical properties of cohesive soil depend on the micro-structure of the soil.Macro-physical mechanics experiments cannot fully explore the micro-mechanical behavior of cohesive soil particles.Therefore,more and more researches use numerical simulation methods to analyze the macro-mechanical properties of clay from the microscopic perspective.Perform analysis.Discrete element method is a numerical calculation method based on the theory of interaction between discrete unit bodies,which is suitable for simulating the force and deformation of soil and other granular materials.For viscous granular materials,there are many discrete element contact models commonly used at present,but most of them are elastic contact models,which cannot fully express the complex stress-strain relationship between viscous particles.Based on this,this paper develops a discrete element numerical simulation method that can equivalently characterize saturated clay by establishing a viscoelastic-plastic stress relationship model between cohesive particles,and further conducts numerical simulation research on the mechanical properties of cohesive soil;compensates for the physical test The lack of research on cohesive soil establishes a numerical simulation basis for in-depth study of the macro-micro mechanical properties and correlation of cohesive soil.This study is based on the EP-cohesive-contact-model of the cohesive particle elastoplastic discrete element contact model,and introduces the loading stiffness,unloading and reloading stiffness,viscosity,viscous stiffness and other parameters related to the circulation path to characterize the circulation of the clay particles.The complex mechanical behavior under load,and the further establishment of an element contact model suitable for cohesive soils,not only can well express the visco-elasto-plastic mechanical action between cohesive soil particles,but also reflect the unique compression and consolidation of clay Mechanical properties.Furthermore,the discrete element numerical simulation method of equivalent saturated soil considering the deformation of solid particles,the generation and dissipation of pore water pressure,the simulation method distinguishes the discrete units of pore water and solid particles,and represents the body through different deformation stiffness parameters.Change characteristics,and then reflect the mechanical behavior of saturated soil during the loading process.Regarding the establishment and development of new contact models and equivalent simulation methods,this paper first conducts theoretical derivation,and then realizes it by computer programming.This paper analyzes the force and deformation process of two cohesive particle elements under cyclic loading,further explores the accuracy and rationality of the cohesive soil particle contact model,and deeply analyzes the interaction between particles during the model operation,which reflects the inter-particle interaction.The mechanical properties of visco-elasto-plasticity;the equivalent saturated soil discrete element simulation method is used to establish an isotropic soil compression numerical model to verify the rationality and accuracy of the equivalent saturated soil discrete element numerical simulation method,and to further analyze the soil During the compression process,the micro-particle contact relationship develops and the cumulative effect of pore water pressure.Based on the above simulation analysis results,combining the clay particle foundation model with the equivalent saturated soil discrete element simulation method to simulate the triaxial compression test process,and further verify the rationality of the clay discrete element model and method established in this research The simulation can reflect that the compression curve of cohesive soil has a tendency to converge under higher effective stress.The same characteristics also appear in the results of the physical compression test,which illustrates the use of the visco-elastoplastic model of cohesive soil.Simulation,the simulated sample has undergone elastoplastic deformation,indicating that the model can simulate the elastoplasticity of clay well,and can express the visco-elastoplastic mechanical action between clay particles.In addition,the effective stress-pore pressure curve is compared.The results verify the rationality and accuracy of the discrete element numerical simulation method for equivalent saturated soil,and show the development of micro-particle contact relationship and the accumulation of pore water pressure during soil compression.Subsequently,the incremental loading test(IL test)and the constant rate strain test(CRS test)were simulated for two compression and consolidation tests,and the consistency between the simulation and the test results was found.The equivalent saturated clay discrete element numerical simulation method developed by the elasto-plastic contact model(EP-cohesive-contact)can well reflect the microscopic interaction between clay particles,and can also express the macroscopic compression and consolidation characteristics of the soil and its stress State correlation,secondary consolidation characteristics,etc.This numerical method will lay a certain foundation for the in-depth study of the macro-micro mechanical properties of cohesive soils in the future.