Hydro-thermal-mechanical coupling properties and mesoscale simulation of concrete-rock composites

This study examines the essential mechanical and diffusion properties of fiber-reinforced concrete, limestone rock, and their combination with varying interface inclination angles. It focuses on the fracture characteristics, flow behavior, and heat transfer of these composites in the context of hydro-thermal-mechanical (HTM) coupling under triaxial compression. The research is divided into two parts. The first part focuses on studying hydro-thermal-mechanical (HTM) coupling through an extensive experimental investigation. Composite specimens made of fiber-reinforced concrete and limestone rock were fabricated into cylindrical samples with different interface angles of 0°, 15°, 30°, and 45°. Various combinations of hydro-mechanical (HM) tests, thermal-mechanical (TM) tests, and HTM tests were conducted under four different confining pressures (0 MPa, 3 MPa, 6 MPa, and 9 MPa), five water pressures (1 MPa, 2 MPa, 3 MPa, 4 MPa, and 5 MPa), and two temperatures (50◦C and 80◦C). The results indicated that water pressure slightly weakened the strength of the composite and increased its permeability. Temperature had a significant effect, greatly reducing both the strength and elastic modulus of the composite. Meanwhile, confining pressure enhanced the peak stress and deformation capacity while suppressing permeability. The second part of the study focuses on mesoscopic modeling, which has been calibrated and validated against experimental results. This mesoscale model uses a discrete element method that combines the Lattice Discrete Particle Model (LDPM) with the Flow Lattice Model (FLM). This study simulates the damage characteristics, fluid flow, and heat flux of composites under various combined conditions, including confining pressure, water pressure, and temperature. The results include the stress-strain response, failure modes, cumulative fluid volume, penetration depth, and the non-uniform distribution of heat.