Vertical stress distribution under tractor wheeling in a partially deep loosened typic paleustalf

Abstract

Soil amelioration by partial deep loosening and incorporation of gypsum in the loosened “slots” of different widths (70–660 mm) is a new technique for improvement of transistional red-brown earths and other clayey soils in the Riverina region in N.S.W., Australia. The distribution of vertical stresses imposed by wheeling in transverse or longitudinal direction to slots of different widths was investigated. The wheeling was done by a 100-kW tractor with a forward speed of 0.7 km h −1 (contact area pressure 0.11 MPa, contact area 0.36 m 2). The results clearly demonstrate that the protection of the homogenized slotted soil material depends on the slot width, the direction of wheeling and the number of loadings. For both wheeling directions, compaction of the loosened and gypsum-enriched soil material in the slots were smaller. Wheeling in the longitudinal direction always induced higher stress values. Because of the differences in the settlement behaviour between the slotted and the adjacent structured soil, repeated loading results in increasing stress values inside and decreasing stress values outside the slots.