| Soil compaction has resulted in land degradation in large areas of farmland.During the compaction process,the physical properties of the soil are changed,the internal ecological balance is broken,and the fertility of the soil is weakened and the crop yield is reduced.At present,soil compaction research often uses artificial soil sampling in the field to measure static physical indicators such as soil hardness,and then combine crop root growth and microbial activity to describe and analyze the causes and consequences of soil compaction.The formation process is complicated,artificial soil extraction steps are cumbersome and easy to damage the soil structure.Soil samples were collected to system atically study soil compaction for further monitor the stress-strain relationship.The development of field mobile compaction sampling platform is of great significance to the study of soil compaction.The main research contents and work results of this paper are as follows:1)Soil pressure characteristics and stress transmission characteristics during the process of under pressure were obtained through the mechanism analysis of soil compaction.Based on this,the overall design scheme of the intelligent in-situ soil compaction sampling platform is proposed.And the structure design of the platform compaction device,sampling device,lifting mechanism and mobile platform is carried out.At the same time,the hydraulic transmission system and servo transmission system are calculated and selected to realize the precise control of the loading pressure and the collection of soil samples by the platform.Through demand analysis,it is concluded that the monitoring system needs to dynamically monitor the soil surface stress,internal stress and sinkage displacement during the compaction process.In order to control the core,a soil compaction process monitoring system is designed based on STM32 series microcontroller chips.Design and debug from both hardware and software aspects to realize human-computer interaction,and finally testing and debugging the function of the monitoring system for finishing the dynamic monitoring of the stress-strain relationship in the soil compaction process by the platform.Comparing the field soil compaction sampling test with the traditional indoor compaction test,the results show that the intelligent in-situ soil compaction sampling platform can meet the field loading requirements and dynamic real-time measurement of soil stress-strain relationship.2)Through the multi-emphasis testing machine,the indoor soil compaction experiment was performed on the remolded lime concretion black soils and wheat straw.Study on the effect of soil wheat straw content after deep tillage on soil characteristics with taking the remolded lime concretion black soils as the control sample.Research shows: when the wheat straw content in the soil is different,the wheat straw soil still satisfies the Bekker pressure model;by fitting analysis of wheat straw soil sinkage depth of 40 mm,60 mm,80 mm,100 mm,resulting that the relationship between the ratio of wheat straw and the soil carrying capacity satisfies first-order polynomial model;the internal friction and cohesion angle deformation modulus and deformation index parameters of 0%,15%,30%,45%,and60% wheat straw soils by volume were determined by data fitting;from the soil characteristics analysis,the soil deformation index is affected by the content of wheat straw.The relationship between the ratio of the wheat straw and the soil deformation index meets the second-order polynomial model.As the proportion of wheat straw rises,the soil deformation index gradually decreased from 2.55 to 1.68,and the highest soil deformation index was 2.59. |
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