An integrated constitutive model has been developed for rock-like materials, incorporating confinement-sensitive damage and bi-mechanism plasticity. The model aims to improve the capability of the conventional damage model in depicting the strengthening and brittle-to-ductile transitions that occur under both active and passive confinement conditions. A thermodynamic analysis of energy transformation and dissipation, considering both damage and plasticity, underpins the model's development. The model, rooted in damage-plastic theory, has been divided into two sub-models: (1) Confinement-Sensitive Model: This sub-model addresses the strengthening and ductility enhancements due to active confinement stress. It effectively captures the mechanical responses of rock-like materials under various levels of active confining stresses. (2) Endochronic Dilatancy Model: Based on endochronic theory, a separate dilatancy strain model is proposed, which effectively facilitates the interplay between lateral dilatancy and the growth of passive confining stress. Both sub-models, as well as the integrated model, have undergone validation using experimental data, including uniaxial tests, cyclic loading tests, actively confined tests, and passively confined tests of rock-like materials. These validations confirm the model's accuracy and reliability in predicting the mechanical behavior of rock-like materials under complex loading conditions.

Rock joints in fault zones are commonly filled with fault gouge, where clay fillings are common. Until now, the shear characteristics of filled rock joints under different moisture contents and shear rates have not been well understood. This work investigates the mechanical behaviour of rock-like materials with clay-filled joints under compression-shear loading. A self-developed rock shear test system was used to conduct direct shear tests on rock-like materials under three normal stresses and five shear rates. Six types of natural red clay with different moisture contents were selected for filling. The coupling effects of the moisture content and shear rate on the mechanical properties of rock-like samples with clay-filled joints were investigated. Furthermore, the failure characteristics of the failure surfaces of rock-like materials after shearing were scanned via 3D scanning. The test results show that the moisture content of fillings and shear rate significantly affect the shear characteristics of rock-like materials with filled joints. The plastic limit moisture content is a critical point where the shear rate has the least effect on the shear strength. Under dry soil filling conditions, the degree of shear damage on the shear plane is the smallest. The present results can provide guidance for slope protection projects.