Experimental Study On Soil Penetration Resistance Characteristics And Design Of Testing Device

With the popularization of agricultural mechanization,the frequency of large vehicles entering the field is increased,leading to soil mechanical compaction,soil compaction caused porosity and bulk density increased,which led to changes in soil structure and affect crop growth.At present,the measurement method of soil penetration resistance is used to study the compaction degree of soil.The most common method is to measure the penetration resistance.The measurement of penetration resistance is often affected by various factors,this paper mainly studies the relationship between soil penetration resistance and depth,the relationship between soil penetration resistance and cone penetration speed,influence of cylindrical groove bottom.By measuring the penetration resistance,the purpose of measuring and analyzing the state of soil structure can be achieved.In this paper,including five parts to study the characteristics of soil penetration resistance.(1)Research status at home and abroad is analyzed,and the research trend of soil penetration resistance is studied.Through the research and analysis of the previous scholars,we can find out the reference and deficiency in the research.Referring to a large number of literatures,it is found that the research on soil penetration resistance is mainly simulation analysis and experimental research is less.Foreign scholars in the study of soil penetration resistance,including theoretical analysis,simulation analysis and experiment,give the theoretical formula,but theoretical and experimental weak.Therefore,this paper attempts to use theoretical mechanics to research the relationship between penetration resistance and depth,through experiment to research the influence of penetration velocity and buck bottom to penetration resistance.(2)Experimental analysis the influencing factors of speed on penetration resistance.penetration rate in the range of 5mm/s-40mm/s,the speed has little influence on the penetration resistance test results;Then,respectively prepared soil samples with different height,research effects to soil penetration resistance of the cylinder at the bottom of the trench,found the experimental curve of different soil height with different depth point position,and the turning point distance trough bottom distance is basically the same,through increased penetration height of penetration test soil samples to avoid the influence of the experimental phenomena by the buck bottom;The penetration of rice,soybean and soil,respectively,analysis of the relationship between penetration resistance and depth,through the experimental data,the fitting curve,the correlation coefficient curve shows better penetration resistance and depth can be used two times number Formal representation.(3)Theoretical analysis,through the way of theoretical mechanic to analyze the stress of cone penetration process of penetration process,then the corresponding calculation formula based on soil mechanics,the force analysis formulas based on the principle of soil mechanics;Secondly,the volume strain stress analysis,according to the cone penetration process.With the increase of depth,soil volume deformation of a growing proportion of the soil is compressed,and soil reaction on the cone,through the theoretical calculation of cone penetration process,research the relationship between soil and cone penetration resistance.(4)Simulation study,simulation 30mm/s penetration rate,cone penetration test,through the simulation data,further analysis of the relationship between penetration resistance and depth.The simulation is based on the spherical particles as the basic particles,results show that the curve is small and the fitting effect is good.(5)Through the analysis of experimental data,based on the ASAE standard,designed a portable electric type soil penetration resistance test device,the device has the advantages of simple structure,convenient carrying,labor saving,suitable for use in field experiment.The results show that with the increase of penetration depth,penetration resistance,penetration resistance and depth can be used two times curve representation,fitting coefficient is 0.90;In the range of 5mm/s-40mm/s penetration speed,impact of penetration speed on penetration resistance is very small;At the same time,the soil at the bottom of the trench has significant influence on the penetration resistance,influence range is about from the bottom of the range of 150mm.