Numerical investigation of creeping rockmass interaction with hardening and shrinking cemented paste backfill

Abstract

Revealing the interaction mechanism between the time-dependent deformation of rockmass and hardening backfill are important for successful mining design. Based on laboratory tests and numerical simulation, a framework has been established to simulate the hardening CPB in backfilled stope, which could consider the strength evolution characteristics, stress curing conditions, filling rate and shrinkage strain of hardening CPB. Results show that three interaction process could be happened after the CPB poured into stope; the stress distribution in CPB affected by the combination of stress arching and squeezing effect when the rheological effect of rockmass is significant in deep backfilled stope, and the squeezing effect makes the stress in CPB exceed its self weight stress; The hardening process, filling rate, stress curing conditions and shrinkage deformation of CPB influences significantly on the stress distribution of CPB itself and lateral deformation of the surrounding rockmass. It is necessary to consider the delayed supporting effect of CPB having obvious shrinkage characteristics, and this delayed supporting effect becomes more significant with to prolong of the delay filling. By analyzing the hardening process, curing stress, filling rate and shrinkage deformation of CPB during hardening process, the new mechanism of the interaction between CPB and surrounding rockmass is revealed, which can provide a theoretical basis for improving the support design of mine backfill.