Thermo-chemo-mechanical cohesive zone model for cemented paste backfill-rock interface

Abstract

A thermo-chemo-mechanical cohesive zone model (CZM) is proposed to describe the shear behaviour of the interface between cemented paste backfill (CPB) and rock under the coupled effects of temperature and binder hydration. To quantitatively evaluate the thermal effect on the binder hydration, an equivalent thermal age is put forward to express the contribution of temperature to the mechanical properties. The interface shear strength properties (e.g., adhesion and friction angle) are then formulated with the equivalent thermal age. Besides, the evolution of the modes I & II fracture toughness of the CPB/rock interface cured at various thermal conditions is experimentally investigated and incorporated into the CZM. The proposed thermo-chemo-mechanical CZM is validated against the measured data from the direct shear tests on the CPB/rock specimens cured at temperatures of 2 °C, 20 °C, and 35 °C for 1, 3, 7 and 28 days. The good agreement between the predicted results and the laboratory measurements proves the satisfactory predictability of the thermo-chemo-mechanical CZM. The results of the sensitivity analysis indicate that the proposed CZM is sensitive to the variations in friction angle, adhesion and modes I & II fracture toughness.