Pull and lift forces on multiple cage wheel lugs when operating in wet clay soil

Abstract

The forces acting on multiple cage wheel lugs were measured when operating in wet clay soil. In a previous study, it was observed that the soil behaviour under the second and subsequent lugs was the same; therefore the forces under these lugs will be the same. Hence only two lugs were used in this study. The effects of soil moisture content, lug sinkage, slip and spacing on lug forces were studied. The lug normal and tangential reactions were measured with the help of strain gauged transducers. These forces were then converted to lug pull and lift forces. It was observed that lug forces on the preceding lug were always higher than those on the succeeding lug. For both the lugs, an increase in soil moisture content caused a decrease in lug forces, but an increase in lug sinkage caused an increase in lug forces. The lug slip did not affect the forces on the preceding lug, but it showed a significant effect on the forces on the succeeding lug. The lug spacing affected the forces on the succedding lug. The comparison of forces predicted by the conventional passive earth pressure theory and measured forces showed that the theory overestimated the lug forces for both lugs. The overestimation was higher for the succeeding lug forces than for the preceding lug forces.