A NUMERICAL STUDY OF THE STRESSES IN BACKFILLED STOPES OVERLYING A SILL
MAT
Mohamed Amine Sobhi, Li Li, Michel Aubertin
Department of Civil, Geological and Mining Engineering, École Polytechnique de Montréal, Montreal,
Quebec, Canada
ABSTRACT
With the continuous reduction of mineral resources at shallow depth, more and more mines have to go
deeper beneath the earth's surface to reach the ore zones. This increase in mine depth leads to a natural
stress increase, which also raises the stresses around mine openings. This may result in ground instability,
including the risk of rock bursts or exceedingly large opening closure. Stope backfilling is a well known
solution to improve the ground stability condition. It also has the advantage of reducing the mining wastes
disposed on the surface, thus helping to reduce the environment impact from the industry. However, most
available solutions for backfill design were developed for shallow mines. Thus, the influence of mine depth
is not explicitly taken into account. In this paper, a numerical study is carried out to evaluate the stresses in
backfilled stopes overlying a sill mat. The stresses within the rock mass ore and backfill pillars (sill mats)
are also evaluated. The influence of mine depth as well as other parameters on the stress distribution within
backfilled stopes and pillars is illustrated with simulations results. These show that the mine depth may
significantly affect the stress distribution, indicating that the some existing solutions for backfill design
may need to be revised.
KEYWORDS
Mine depth, Backfill, Sill mats, Stresses, Numerical modeling