Studies On Correlation Between Soil Carrying Capacity And Physical Parameters Of Paddy Soil

Paddy field is one of the most important cultivated land in China,with an area of 30747,000 hectares,accounting for 26% of the total cultivated land area.However,the high resistance and energy consumption of operating equipment in paddy field have always been a prominent problem in paddy field production.Paddy field operation equipment relies on paddy field as a carrier to play a role.The resistance of the equipment is mainly influenced by the mechanical characteristics of paddy field soil,and is closely related to the factors such as soil texture,water content and density.Bearing characteristics,including shear characteristics,compression characteristics and hardness,are the basis of research and development of paddy field operating machinery.However,the existing research lacks the results of correlation between physical parameters such as plastic soil texture,water content and bearing characteristics,and can not provide theoretical support for the design and parameter optimization of paddy tractors and operating machinery.In order to obtain the correlation between paddy soil load-bearing characteristics and physical parameters,the effects of soil texture,water content and density on shear properties,compressive properties and firmness of plastic paddy soil were studied.The main results are as follows:(1)The soil texture of 14 paddy fields in Zhejiang,Jiangsu and Anhui was determined by hydrometer.Eight types of paddy soils were selected according to clay gradient,which basically covered all paddy field soil types.The clay content ranged from 20% to 40%,the plastic limit of soil samples ranged from 18.5% to 22%,and the liquid limit ranged from 49.5% to 55.5%.(2)Experimental study on shear properties of paddy soilTaking cohesion and internal friction angle of soil shear characteristics as test indexes,clay content,water content and density as test factors,three factors and five levels quadratic orthogonal combination were used to carry out the experiment.The results show that the contribution rate of single factor to soil cohesion from high to low is clay content,water content and density,and the interaction factor from high to low is clay content × water content,clay content × density,water content × density;the contribution rate of single factor to soil internal friction angle from high to low is water content,density,clay content,and the interaction factor from high to low is clay content.Grain content × water content,water content × density,clay content × density.The prediction model between soil shear characteristic parameters and soil physical parameters in plastic paddy field was established,and the error between the predicted and measured values was less than 10%.(3)Experimental study on pressure-bearing characteristics of paddy soilThe cohesion modulus,friction modulus and subsidence coefficient of soil compressive properties were taken as test indexes,clay content,water content and density were taken as test factors,and three factors and five levels of quadratic orthogonal combination were used to carry out the test.The results showed that the contribution rate of single factor to soil cohesion modulus from high to low was clay content,water content and density,and the contribution rate from high to low was clay content × water content,clay content × density and water content × density.The contribution rate of single factor to friction modulus from high to low is clay content,water content and density.Considering the interaction between the two,the contribution rate from high to low is clay content × water content,clay content × density,water content × density.The contribution rate of single factor to subsidence coefficient from high to low is clay content,water content and density.Considering the interaction between the two,the contribution rate from high to low is clay content × water content,water content × density,clay content × density.The prediction model between the soil pressure characteristic parameters and the soil physical parameters of plastic paddy field is established.The soil shear pressure parameters can be predicted in a certain range through the soil physical parameters.(4)Study on Paddy Soil Hardness TestTaking soil hardness as the experimental index and clay content,water content and density as the experimental factors,three factors and five levels quadratic orthogonal combination were used to carry out the experiment.The results showed that the contribution rate of single factor to soil hardness from high to low was density,clay content and water content in turn;considering the interaction between two factors,the contribution rate from high to low was clay content × density and content in turn.Water content × density,clay content × water content.The prediction model between soil hardness and soil physical parameters in plastic paddy field was established,and compared with the measured values of soil hardness in situ,the error was less than 10%.(5)Experimental study on working performance of tracked tractor based on paddy soil bearing characteristicsUsing the established mathematical model of load-bearing characteristics,a paddy field soilcrawler tractor coupling model was established in Recurdyn,a multi-body dynamics software.The driving performance(travel resistance,subsidence depth,slip rate)was taken as the test index,clay content,water content,density and driving speed were taken as test factors,and four factors,five levels and quadratic orthogonal combination was used to carry out the simulation test.Experiment.The results show that the contribution rate of single factor to driving resistance from high to low is water content,driving speed,density and clay content in turn.Considering the interaction between the two factors,the contribution rate from high to low is clay content × density,clay content × driving speed,clay content × water content,water content × density,density driving × speed,water content × driving speed.The contribution rate of each factor to subsidence depth from high to low is water content,density,clay content and driving speed.Considering the interaction between them,the contribution rate from high to low is clay content × water content,clay content × driving speed,water content × driving speed,density × driving speed,clay content × density,water content × density.The contribution rate of each factor to slip rate from high to low is water content,driving speed,density and clay content.Considering the interaction between the two factors,the contribution rate from high to low is water content × driving speed,clay content × driving speed,clay content × density,water content × density,clay content × moisture content,density × driving speed.