Development and verification of adhesion models for track shoes operating on clay soils

Adhesion between track shoes and clay soil has a significant effect on vehicle track-terrain interaction. To correctly evaluate the adhesion between track shoes operating on clay soil, tri-axial shear test (TST), traction test (TT) and direct shear test (DST) were performed on clay loam (C), sandy loam (S) and loamy clay (L) under different moisture contents (w), shear rates (v) and normal loads (σ). In the TST, the effect of w on cohesive strength and internal friction angle was investigated. Cohesive strength initially increased rapidly with the increase of w then decreased slowly when w reached the plastic limit (PL). Internal friction angle decreased gradually as w increased and then decreased sharply when w＞PL. In the TT, shear strength increased slowly with the increase of shear rate (v) and then stabilized. In the DST, shear strength increased linearly with the increase of normal load (σ). Thereafter, soil shear strength equation considering w, v and σ was modified based on the results of TST, DST and TT. On this basis, considering the structural parameters of track shoe, adhesion models were developed and verified. The predicted and measured values of normal adhesion and tangential adhesion on C, S and L had strong linear correlations with the coefficients of determination ranging from 0.9665 to 0.9932, and the relative errors were 2.56%, 3.16% and 2.67%, indicating that model derivation and correction were effective. The proposed adhesion models can therefore provide a theoretical basis for the desorption design of track shoes for operation on clay soils.