Mechanical properties of uniaxial compression of total tailings paste under lateral restraint effect

After the filling of paste into the mined-out area, significant disparities are evident between the mechanical characteristics and the unconfined conditions, primarily caused by the lateral extrusion of the surrounding rock. To research the mechanical properties of paste under the influence of lateral restraint effect, a device was developed to apply lateral pressure to the paste. This was then combined with an existing uniaxial press machine to carry out uniaxial compression testing of the paste subject to lateral restraint effect. The device was used to carry out uniaxial compression tests under different curing ages and dry and wet conditions under the lateral restraint effect, and compared with the unconfined condition. The study revealed a considerable increase in the paste's strength caused by the lateral restraint effect, resulting in a growth rate ranging from 12.35% to 64.51%. The mathematical model of lateral stress and strength was established, and it was found that the two showed a significant quadratic function relationship. By acquiring the stress-strain data of the loading process, the evolution characteristics of the stress-strain curve of the paste under the influence of the lateral restraint effect are revealed, and the change rule of the elastic modulus is explored. Under the influence of the lateral restraint effect, the growth rate reaches 1.93% to 64.04%. When comparing the crack propagation characteristics of the paste with and without the influence of the lateral restraint effect, it was observed that the failure mode of the paste under uniaxial compression shifts from tensile failure to shear failure. Finally, this paper proposes the strength design method for backfill with considerations to the lateral restraint effect. The reliability of the suggested method is established through actual sampling results in the mine. The research findings hold significant guiding value for the secure and efficient extraction of paste backfill mines.