In this work, a series of triaxial consolidated drained shear tests were used to investigate the stress–strain relationships of weathered red sandstone soil and lime-treated weathered red sandstone soil. Firstly, the triaxial consolidated drained shear test results were used to analyze the relationship between deviatoric stress
$$q$$
, axial strain
$${\varepsilon }_{1}$$
, shear strain
$${\varepsilon }_{\mathrm{s}}$$
, and volume strain
$${\varepsilon }_{\mathrm{v}}$$
. Secondly, the yield surface of...