Cemented paste backfill (CPB) and rock interface interaction causes the formation of an interfacial loading and affects the thermal, hydraulic, mechanical, and chemical processes in bulk CPB and thus its in-situ behavior. In this study, a new meter-sized column model is developed to systematically investigate the multiphysics processes in CPB under interfacial loading. The obtained results discover that for the mechanical process, the interfacial loading leads to a reduced settlement and a weakened stress level in CPB. For the hydraulic process, lower matric suction and smaller moisture content coexist in CPB under interfacial loading. For the thermal process, the interfacial loading weakens the porosity-dependent thermal conduction and causes retardation in temperature variation relative to the ambient temperature. For the chemical process, weakened cement hydration with smaller electrical conductivity was observed in CPB under interfacial loading. Therefore, the obtained results reveal the linkage between the interfacial loading and multiphysics processes in CPB and thus contribute to an in-depth understanding of the multiphysics behavior of CPB in underground mines.