Abstract
Measuring the stress in situ by bulldozers used as compaction equipments on different types of soil (Table 1, 2), several general characteristics were observed and they are as follows:
(1) As a bulldozer can be driven even when a portion of its crawler tracks are not in contact with the ground, the contact pressure of the bulldozer will change in accordance to the conformation of the ground surface it is moving over.
(2) Most measured stresses in situ are 7-13 times larger than the stresses calculated from nominal contact pressure (Fig. 3-9).
(3) The stresses calculated statically from the theoretical model (Fig. 11, Table 3) coincide with the measured stresses of a bulldozer not in motion, but is considerably smallr than measured stresses when a bulldozer is driving
(4) The speed of bulldozer while compacting is the faster, the stress in situ is the larger.That is, the stress while compacting in the 3rd gear speeds is larger, by about 70%, than the stress in situ in the 1st gear speeds.
(5) The stress in situ in the case that a bulldozer is drawing a tamping roller are larger, by about 30%, than one in the case that the bulldozer is not drawing anything.
(6) The measured stresses in situ are also affected by the characteristics of soils as cohesive soil, rock materials and so on.
