R. L. Kushwaha, Ph.D., Professor Subsoil Force Profile due to Human Locomotion

A force platform, which can provide three dimensional forces and moments on its top surface, was used in this study. Soils of varying depth were packed on the top surface of the platform to measure the forces transferred from the soil surface. Experimental variables included subjects (people), soil depth, soil type, moisture content, and compaction level. Soils were sand and clay with medium and high compaction levels. Each soil included two moisture contents and five soil depths up to 200 mm. There were five subjects with mass ranged from 45 to 100 kg involved in this study.
The profiles of maximum forces in the subsoil were established for different subjects at a depth up to 20 cm. The impulse of foot and soil interaction were calculated and used in evaluating the effect of different subjects on the force transfer in soil. The results indicated that loose soil can transfer larger force to subsoil than dense soil; test results showed that heavier subjects also created larger subsoil forces than lighter ones. The effect of soil depth on subsoil impulse was not always significant depending on the soil conditions. For the sand with 5.5% moisture content and bulk density of 1800kg/m3, soil depth significantly affected subsoil impulses. For the sandy loam soil, the mass of subject increased from 50 to 100 kg resulted in 100% increase in subsoil impulses at all four depths; for the sand, the mass of subject increased from 55 to 100 kg approximately resulted in 80% increase in subsoil impulses under all four depths regardless of moisture content and bulk density. This study provides a basic database for designing new equipment and evaluating existing machines for neutralizing antipersonnel landmines.