CANMET's rock mechanics research at the Kidd Creek mine

Abstract

The Kidd Creek mine of Texasgulf Metals Company started as an open pit and later converted to an underground operation. In 1972, a cooperative rock mechanics research project was initiated between the company and the Mining Research Laboratories of CANMET. Research was concerned with stability of the hanging wall pit slope as it was undercut by the underground operations and with ground control aspects of the blasthole open stoping method employed underground. Geotechnical investigations on critical joint orientations and shear resistance along these discontinuities indicated that a plane or rotational shear type of instability of the hanging wall slope was unlikely. This was cohfirmed by two- and three-dimensional finite element models, although sloughing of the hanging wall shear zone was predicted. Further confirmation on slope stability was obtained by monitoring slope displacement which showed a cause-and-effect relationship while mining was taking place and the magnitude was within the limits predicted from the two finite element models. During the time these studies were being done, stopes were being blasted through at the southern end while the pit was being deepened at the northern end. No instability of the pit walls interrupted either operation and the pit was completed in 1977. Underground, field stress measurements were taken down to a depth of 850 m, indicating that the stress regime was similar to that in other mines in northern Ontario with horizontal stresses being greater than vertical stresses. Deformation measurement around underground stopes showed that expansion of the footwall shear zone was ten times greater than the pillar wall. There was a distinct cause-and-effect relationship between blasting and deformation. Pillar strength was estimated using a size/strength relationship, obtained from testing samples up to 25 cm in diameter, incorporated into an empirical strength equation. A preliminary analysis on pillar stability suggested that stresses on the pillar edge and corners could be of the same magnitude as pillar strength. This could explain the cases of pillar sloughing, but adverse structural geology could also have caused this sloughing.

Deformation of slopes as a cause of underground mining activities: three case studies from Ostrava–Karviná coal field (Czech Republic)

“…However, surface impact from underground mining activity is very well known and reasonably well understood, as a result of the effect of underground mining activities; many hazards, undesired structural and environmental problems on the surface are being addressed in many countries. Many case studies are reported related to the impact of the underground mining activities, such as Crane (1929), Allen (1934), Rice (1934), Hedley et al (1979), Robertson and Kirsten (1984), Whittaker and Reddish (1989), Charette and Hamel (1993), Wang et al (1995), Betournay (1994Betournay ( , 1995Betournay ( , 2002, Betournay and Wang (1997), Perski and Jura (2003), Marschalko (2004), Marschalko (2011a, b, c), Malgot and Baliak (2004), etc.…”