Numerical modelling of the effect of weathering on the progressive failure of underground limestone mines

TL;DR

This paper develops a numerical model to simulate how weathering causes gradual failure in underground limestone mines, considering hydrochemo-mechanical processes like water infiltration, CO2 migration, and limestone dissolution.

Contribution

It introduces a coupled hydrochemo-mechanical numerical model for progressive failure due to weathering in underground limestone mines, which is a novel approach.

Findings

The model successfully simulates the weathering-induced failure process.

Weathering significantly reduces the strength of limestone over time.

Numerical results demonstrate the potential for predicting mine stability deterioration.

Abstract

The observations show that the collapse of underground limestone mines results from a progressive failure due to gradual weathering of the rockmass. The following stages can be considered for the limestone weathering and degradation process in underground mines: condensation of the water on the roof of the gallery, infiltration of water in the porous rock, migration of the air CO2 molecules in the rock pore water by convection and molecular diffusion, dissolution of limestone by CO2 rich water and consequently, reduction of the strength properties of rock. Considering this process, a set of equations governing different hydrochemo-mechanical aspects of the weathering phenomenon and progressive failure occurring in these mines is presented. Then the feasibility of numerical modelling of this process is studied and a simple example of application is presented.