Modeling of pressure on retaining structures for underground fill mass

Abstract

To retain fresh cemented paste backfill (CPB) (a large fill mass made of man-made fine soils that undergo cementation) in a stope (underground mining excavations), a retaining structure or wall (called a barricade) must be constructed at the base of the stope. Due to the coupled thermo-hydro-mechanical-chemical (THMC) processes that occur in CPB, changes in the total horizontal stress and pore water pressure (PWP) take place with backfilling operations that are flexible, which directly affects the stability of the barricade. Hence, an investigation of the changes and distribution of barricade pressure is crucial for the assessment of the stability of CPB and the barricade. In this paper, an integrated multiphysics model composed of a fully coupled THMC model, a fully coupled multiphysics model that analyzes the consolidation process in CPB and an elastoplastic model that analyzes changes in the interface behavior during the interaction of rock mass/backfill is adopted. The predictive ability of the model is validated by the good agreement between the simulation results and in-situ measurements from a series of field monitoring programs. Then, the validated multiphysics model is used to numerically investigate the changes and spatial distribution of barricade pressure under various conditions (including elapsed time, barricade location and shape, initial temperature, and drainage conditions). The obtained results can provide practical insight into the factors that affect the geotechnical stability of barricade structures.