Study On The Failure Characteristics Of The Grassland Composite Soil Layer Under The Action Of Narrow Tillage Tools

In recent years,due to the deterioration of natural conditions and the destruction of human activities,grassland has been degraded to varying degrees,which hinders the effective performance of its ecological services and production functions.Mechanization improvement technology is one of the effective means to realize grassland ecological restoration and promote the development of grassland animal husbandry.However,the R&D and optimization design of special tillage components for mechanical improvement need to be supported by interaction between tillage components and grassland composite soil layer to be the support.Therefore,the failure effect of grassland composite soil layer under the action of narrow tooth tillage components was studied in this thesis.The main contents are as follows:By investigating the background information of the test area,the physical characteristic parameters such as soil bulk density,water content and porosity of the grassland soil were obtained,and the soil grain size was analyzed by soil texture analysis experiment.The results show that the soil bulk density is in the range of 1.10～1.62g/cm~3,the water content is in the range of 7.1%～13.65%,the porosity is in the range of39.03%～58.51%,and the soil type is sandy loam.Based on machinery design and soil dynamics theory,analyses the force situation of farming unit operations and movement,put forward the cultivation parts grass coupling failure test scheme design,3-D modeling of the test bed,equipment selection and manufacture processing,test bench mainly includes frame,farming components,clamping device and data acquisition device,etc.At the same time,the field performance test of the test bed was carried out,and the results showed that the test bed was in good performance,in line with the expected objectives,and in line with the requirements of subsequent grassland tillage experiments.Field experiments were conducted to study the failure effect of the composite soil layer of grassland under the operation of the shovel handle tillage unit,the deep loosening tillage unit and the disc trenching unit,and to analyze the movement,operation resistance and disturbance of the tillage unit with different structural parameters at different working depths.The Results show that(a)the thickness of the shovel handle class farming components,blade angle and the angle of the grave assignments resistance and disturbance parameters have the significant influence of grassland,under different working depth,the thickness of the shovel handle,the influence of the blade angle and the angle of the grave homework resistance there is interaction,when the thickness is 14mm,blade angle is 45°,the grave angle is 45°,The tilling unit has the minimum force and produces a small dumping rate.The tilling unit with shovel handle can produce appropriate disturbance to the grassland composite soil layer,with soil disturbance coefficient≥51%and soil fluidity≤40%.(b)with the increase of depth,deep loosening shovel class assignments farming components resistance increased significantly(P<0.05),the depth of different assignments,wings type deep loosening shovel resistance decreases with increasing wings angle,when the operating depth of 15cm,wings angle of 150°,deep loosening shovel operation of least resistance,arrow blade type stress significantly smaller than the wings shovel,Under different operating depths,the soil disturbance coefficient after operation is more than 63%,and the soil fluidity is between 38%and 49%.(c)the operating resistance of disc ditching components is small.When the operating depth is 5cm,the force of single disc is significantly lower than that on the double disc,and when the operating depth is 10 cm,the force of corrugated disc is significantly lower than that on the single disc.After the operation of the disc grooving parts,narrow or concave grooves are left on the surface,which has little disturbance to the ground surface.This study provides theoretical reference and data support for the R&D and optimization design of special tillage components for grassland improvement.