Study On Wheeled Vehicle Traction And Adhesion In Soft Clay Soil

Clay soil is widely distributed in China and has long being a problem for agricultural production, where machinery design and application is required. Due to its complexity of the physical and mechanical state, soft clay soil largely can affects vehicle trafficability, restricting power output from the engine, and resulting into tire sinkage, worsened rolling impedance and reduced adhesion. Thus the study of the traction and the adhesion performance of wheeled vehicle is still necessary for the practice. The experiment focused on soil mechanical property test and vehicle trafficability evaluation, and combined indoor soil bin experiment and field trials to illustrate wheeled vehicle performance in soft soil.The shearing strength and the cone index of the soft clay soil affected wheeled vehicle trafficability and adhesion. Precision control on its states is a pre-requisite for a systematic test. A non-standard compacting procedure was applied to prepare remolded soil sample, in which controlled compacting works were used to regulate soil densities for soils in different moisture contents. The reconstructed soil samples were subjected to direct shear on the SDJ-1shearing device and a micro-penetrating testing machine of self-developed. These tests resulted to the relationship among soil shearing strength, cone index and soil moisture content, density, as well as the linkage between the shearing force and the cone index. Mathematical models for these relations were provided which include a2nd order polynomial model from the fitted curve of the penetrating resistance and displacement relation, and a model between cone index and soil moisture content and densities.The first problem faced with wheel adhesion study in soft clay soil condition is the reconstruction of the test soil base. As the layered soil placement plus rolling compacting method provides a poor adhesion between soil layers, and the prepared soil state variables were hard to be quantified, the Proctor compacting test method from geotechnical engineering was introduced into the experiment. This made it possible for the mono-wheel testing system to be tested on well controlled soil base. The indoor traction test illustrated the relationship among the maximum traction force, compacting work and soil moisture content, leading to a2nd order polynomial model. Further test in outdoor conditions confirmed the validity of this model. To illustrate the traction and adhesion performance of the vehicle wheel in real soil state, in situ penetration test was performed in field conditions. Intact soil was sampled and tested in laboratory for its shearing strength and the maximum shearing strength. This was complimented with further wheel traction test on the same site to achieve the real traction performance of the wheel. The triangle relation among the cone index, shearing force and wheel adhesion was studied. Relationship between the predicted value and the tested value of the cone index and maximum adhesion was investigated, results of which was the provision of an evaluating system for vehicle adhesion.