MODELING SOIL COMPACTION UNDER PNEUMATIC TIRES IN CLAY SOIL

A compaction model was developed by dimensional analysis to predict so il packing state under agricultural pneumatic tractor tyres. Different parameters which affect the soil compaction, namely tyre size, inflat ion pressure of the tyre, axle load, number of tyre passes and differe nt soil conditions, were considered for analysis. The compaction was q uantified in terms of changes in dry bulk density of a clay soil. The details of dimensional analysis and determination of different dimensi onless numbers involved in soil compaction processes for modelling pur poses are given. Experiments were conducted to study the effect of var ious wheel and soil parameters on soil compaction and develop relation ships between various dimensional quantities. The results revealed tha t axle load and number of tyre passes were the most prominent paramete rs which affect soil compaction significantly. The soil compaction was increased with an increase in the axle load. Maximum soil compaction occurred immediately after the first pass of the tyre wheel and during later passes the compaction decreased exponentially. Though soil comp action decreased with reduction in the tyre inflation pressure to an a cceptable limit, its effect was not considerable within a small range of variation. Models to predict soil compaction for different soil and machine parameters were developed by using experimental data. These m odels can be used to predict soil compaction caused by agricultural ve hicle traffic in clay soil.