Dynamic DEM Simulations On Direct Shear Test Of Sandy Soil And Shovelling Of Soil And Rock

Soli is a kind of multiphase material,constituted by minerals,organic matters,moisture,gases and other matters.It is broadly known for its complicated composition and nonlinear mechanical specialities.The shear strength is one of the most significant properties in soil mechanics.The cognition of shear property has great importance for improving engineering quality and ensuring construction safety.The blade mechanism is widely equipped in various engineering and agricultural machinery.As a part contacting the media directly,the blade mechanism tend to be broken and wearing easily,which means engineering outcome is determined by its design and strength to a great degree.Therefore the design of blade should be optimized based on theoretical research in order to relieve mechanical abrasion and increase work efficiency.The following content is about the main research and conclusions of this study:1.The cylindrical and cubic direct shear boxes are built and soil sample models were designed with PFC3d,and kinds of samples are sheared under different normal loads.Comparisons are conducted between the results of experiment and simulation to adjust the input data and demarcate the micro physical property parameters of soil.The conclusion shows that the shape of box has influence to the shear force curve.The volume of soil sample tends to decrease during shearing process.Velocity,particle size and friction coefficient could affect shear strength.2.The software PFC3d is selected to establish simple blade model and soil material bed is generated according to the data from direct shear simulation.This part focus on the influence of excavating angle,depth and velocity to the resistance of blade and the changing rule.The result turns out that the three projects of 75°,60mm and 80mm/s show greater resistance respectively.Furthermore,when the depth rises up,the resistant force of blade increases,but not linearly.And the resistance tend to fluctuate more obviously at a higher velocity level.3.The bulldozer blade models with different vertical cross section shape,are designed with SolidWorks.Those models will be imported into gravel assembly built in software EDEM,then the excavating and transporting process can be conducted.Horizontal,vertical and lateral forces of different blades are compared and related changing laws are summarized,which suggest that the design of smaller radius is fit to transportation and the one with larger radius has higher efficiency in smoothing ground.