Modelling soil compaction under pneumatic tyres in clay soil

Abstract

A compaction model was developed by dimensional analysis to predict soil packing state under agricultural pneumatic tractor tyres. Different parameters which affect the soil compaction, namely tyre size, inflation pressure of the tyre, axle load, number of tyre passes and different soil conditions, were considered for analysis. The compaction was quantified in terms of changes in dry bulk density of a clay soil. The details of dimensional analysis and determination of different dimensionless numbers involved in soil compaction processes for modelling purposes are given. Experiments were conducted to study the effect of various wheel and soil parameters on soil compaction and develop relationships between various dimensional quantities. The results revealed that axle load and number of tyre passes were the most prominent parameters 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 compaction decreased with reduction in the tyre inflation pressure to an acceptable 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 models can be used to predict soil compaction caused by agricultural vehicle traffic in clay soil.