Evaluating the influence of backfilling on the stability of an abandoned room-and-pillar mine: a case study in northern Spain

Abstract

Bodovalle is a siderite mine located in northern Spain that is currently in the closure phase. The mine was exploited using the room-and-pillar method. Subsidence processes have occurred previously and reached the surface because of the collapse of several pillars into the mine. To prevent such risky situations, the closure plan has been modified and the backfilling of some rooms has been considered. This study aimed to evaluate the global stability of room #1.1 after backfilling. This paper combines the use of traditional techniques, numerical modelling and remote sensing to achieve this objective. Limit equilibrium methods, LIDAR technology and numerical methods-based software were employed to evaluate the stability of rooms and pillars surrounding room #1.1 and considering different backfilling levels. In all possible backfilling scenarios involving room #1.1, the impact on the surface and neighboring rooms is negligible. In addition, no substantial changes in the safety factors and deformations of the neighboring rooms were observed for both studied levels of backfilling. Thus, backfilling is an adequate countermeasure to avoid subsidence.