Numerical Simulation Of Dynamic Triaxial Mechanical Properties Of RCC Under Freeze-thaw Cycles

With the development of Northwest China,roller compacted concrete dam has become one of the important dam types in Northwest China.Due to the severe climate conditions and frequent geological activities in Northwest China,the safety and stability of RCC dam structure are adversely affected.Therefore,it is of great significance to carry out numerical simulation of dynamic triaxial compression of RCC under freeze-thaw cycle by discrete element method.In view of this,based on the discrete element method,this paper carries out dynamic triaxial compression numerical simulation of RCC under different freeze-thaw cycle times,confining pressure and strain rate,obtains the influence of freeze-thaw cycle times,confining pressure and strain rate on the macro and micro mechanical characteristics of RCC,and analyzes the internal failure process of the numerical sample from the micro perspective.The main research work and conclusions are as follows:(1)In the discrete element software,the meso parameters of the RCC numerical model were calibrated,and it was found that five different meso parameters had different effects on the mechanics of RCC under the same conditions,which provided a reference for establishing the RCC model of freeze-thaw damage layer later.(2)A RCC model considering freeze-thaw damage layer is constructed,and the thickness of freeze-thaw damage layer is based on the indoor test results.The model is used to simulate dynamic triaxial compression,and the results of numerical test and indoor test are in good agreement,which verifies the reliability of the freeze-thaw damage model proposed in this paper.(3)Describe the relationship between macro and micro mechanical properties,the displacement and macro deformation of internal particles,the structure of force chain and macro stress,the process of internal meso failure and the relationship between macro stress and strain.Describe the effects of freeze-thaw cycle times,confining pressure and strain rate on macro and micro mechanical characteristics(stress-strain curve and internal particle displacement,force chain structure and meso failure).(4)Through the comparison and analysis of the results of macro physical test and numerical simulation,it is found that the influence of confining pressure on the compressive strength of RCC is greater than that of freeze-thaw cycle under the environment of confining pressure and strain rate.The effect of strain rate on the compressive strength of RCC is obvious.Confining pressure can enhance the compressive strength of RCC,and this effect is more obvious with the increase of freeze-thaw cycles in this test.