Design And Test Of Mixing Cutter For Aeolian Sand Improvement Equipment

The improvement of sandy soil is one of the main measures for controlling sandy soil.Mixing the modified soil materials with sandy soil through mechanized operations can improve work efficiency,and how to efficiently and evenly mix the two is the core issue that needs to be solved.This study explores the interaction mechanism between mixing tools and wind sand soil modified materials.Based on the national standard rotary tiller IT245,its working principle is analyzed.On this basis,a mixing tool specifically designed for wind sand soil improvement is designed.A wind sand soil modified soil material mixing equipment test bench and discrete element simulation model are established,and mixing experiments are conducted.A spatial mixing effect evaluation method is proposed,Evaluate the mixing effect of soil modification materials in both vertical and horizontal directions,and study the influence of equipment operating conditions and mixing tool structure on the mixing effect.The main research content and results are as follows:1.Study the physical properties of windblown sand and soil modification materials,including particle size and mass fraction,moisture content,stacking angle,and stacking density,to provide numerical parameters for the establishment of discrete element models of windblown sand and soil modification materials.Taking the relative error of the stacking angle between the aeolian sand simulation and the physical test as the response value,the contact parameters of aeolian sand and aeolian sand,including impact coefficient of restitution,static friction coefficient and rolling friction coefficient,are calibrated through the orthogonal test of three factors and three levels.Establish a discrete element simulation and indoor test bench for wind blown sand,soil improvement materials,and mixing equipment.2.Propose a method for evaluating the effectiveness of spatial mixing,dividing the Z direction(plowing depth direction)of the mixture of windblown sand and modified soil materials into 5 layers,and using the volume ratio of the modified soil material as the evaluation index for mixing effectiveness;The horizontal direction is divided into X(equipment forward)direction and Y(working width)direction,each direction is divided into three areas,and the coefficient of variation of the volume ratio of the modified soil material is used as the evaluation index for the mixing effect.Then,by comparing and analyzing the simulation and indoor test results,the accuracy of the established discrete element model of windblown sand soil modified soil material mixing equipment was evaluated.The results showed that the average error was 7.22%.3.Analyzing the national standard rotary tiller and the mixing process,analyzing the movement law and force of the rotary tiller,and clarifying the mixing mechanism of the rotary tiller are important theoretical basis for studying the entire mixing process.Use simulation to study the mixing effect of the national standard rotary tiller IT245 under different working conditions,and compare the spatial distribution of soil modification materials in sandy soil under different equipment forward speeds and blade roller speeds.The results show that as the speed of the equipment increases,the volume ratio of soil improvement materials with a depth of 150mm-30 mm shows a decreasing trend in the Z direction,while the volume ratio of soil improvement materials with a depth of 30mm-0mm shows an increasing trend.The coefficient of variation of soil improvement materials in the X and Y directions basically shows a decreasing trend in sequence;As the rotation speed of the cutting roller increases,the volume ratio of soil improvement materials with a depth of150mm-30 mm in the Z direction shows a trend of first increasing and then decreasing,while the volume ratio of soil improvement materials with a depth of 30mm-0mm shows a decreasing trend.The coefficient of variation of soil improvement materials in the X and Y directions basically shows a trend of first decreasing and then increasing.4.Based on the structure of the national standard rotary tiller IT245 and combined with the mixing mechanism of the rotary tiller,a special mixing tool for improving windblown sand soil was designed.The bending and deflection angles of the mixing tool were changed,and the contact area between the mixing tool and the modified soil material was increased,so that the modified soil material was evenly mixed with the windblown sand soil.Use simulation to study the mixing effect of two sets of special mixing tools designed for windblown sand soil,and compare the spatial distribution of soil modification materials in windblown sand soil under different bending and deflection angles.The results show that in the Z direction,the larger the deflection angle of the mixing tool,the larger the volume ratio of the modified soil material.The maximum value of 35.67% is reached when the deflection angle is 60 ° at a depth of 30-0mm,In the X direction,the size of the deflection angle is not significantly related to the coefficient of variation of the volume ratio of the modified soil material.In the Y direction,the magnitude of the deflection angle and the coefficient of variation of the volume ratio of the improved soil material show a decreasing trend;In the Z direction,the larger the bending angle of the mixing tool,the larger the volume ratio of the modified soil material.The maximum value is 36.02% when the bending angle is 130 ° at a depth of 30-0mm.However,in the horizontal X and Y directions,the size of the bending angle is not significantly related to the variation coefficient of the modified soil material volume ratio.5.Compared with the national standard rotary tiller IT245,the mixing effect of the wind sand soil mixing tool is similar.The shallower the depth,the greater the volume ratio of the soil modification material,and the better the mixing effect.In the Z direction,the volume ratio of the wind sand soil mixing tool with a depth of 90-60 mm and a deviation angle of 60-30 mm at 60 ° increased by 3.19% and 5.11%.In the Y direction,the coefficient of variation of the mixing tool with a deviation angle of 60 ° is 3.05% smaller than that of the rotary tiller,and the mixing effect of the mixing tool with a deviation angle in the Y direction is better than that of the national standard rotary tiller.