This paper investigates the deformation characteristics and damage mechanism of the lime-treated expansive soil. A series of mechanical property tests under uniaxial compression

one-dimensional consolidation

and triaxial compression are carried out for Jingmen expansive soil. The results show that the lime-treated soil remains fairly stable stiffness and shear strength even after saturated. Under uniaxial compression

whether unsaturated or saturated

the brittle failure occurs for the lime-treated expansive soil

whereas the untreated expansive soil has considerable plastic deformation capacity. On the other hand

under triaxial compression

the lime-treated samples present shear contraction and strain hardening before failure

with the shear dilatancy when the sample was about to failure and strain softening after failure. Moreover

it is observed that the confining pressure had an inhibitory effect on the brittle failure and the shear dilatancy

but even under the confining pressure is 200 kPa

the deformation of the sample is very small at the failure time

which demonstrates the brittle failure. Based on the mechanism analysis

the Duncan model is selected to describe the stress-strain-strength behaviour of the lime-treated expansive soil. The model parameters are calibrated from the aforementioned tests. The comparisons between the parallel tests and predicted results validate the selected model.