A review of soil strength measurement techniques for prediction of terrain vehicle performance

Abstract This paper reviews techniques for measurement of soil strength and makes recommendationsfor suitable methods for off-road vehicle performance prediction. The cone penetrometer and bevameter were found to be the most appropriate largely because they enable measurements to be made in situ. However, even though the penetrometer is the only technique that can assess variation of soil resistance with depth, neither the cone index nor its gradient with respect to depth is uniquely related to soil cohesion or density, but varies with moisture content and structural state. Furthermore, the formation of soil bodies and compaction zones ahead of the cone effectively changes its geometry and the penetration no longer reflects the original properties of the soil. On the other hand, the bevameter technique only characterizes surface soil properties. Nevertheless, the bevameter provides the closest simulation of vehicle-terrain interaction among all the currently available techniques. The main criticism of the bevameter and also of the penetrometer is that the sizes of the penetration and grouser plates and the cones, respectively, are too small.