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Analysis of backfill and pillar performance in the B-Neath ore body at the Cannon Mine.
Tesarik-DR; Seymour-JB; Mudlin-ME
Minefill 1993: The 5th International Symposium on Mining with Backfill, June 7-9, 1983, Lulea, South Africa. Glen HW, ed. Johannesburg, South Africa: South African Institute of Mining and Metallurgy (SAIMM), 1993 Jun; :55-64
U.S. Bureau of Mines researchers and personnel from the Cannon Mine, Wenatchee, WA, USA, installed rock and backfill instruments in the B-Neath orebody to monitor load transfer during primary and secondary mining operations. Conventional rock-mechanics instruments were used in rock pillars and the mine roof, while backfill extensometers were fabricated by the Bureau for use in the cemented primary stopes. Stressmeters and borehole pressure cells placed in secondary rock pillars indicated that stress changes during primary mining in one secondary pillar were approximately seven times the overburden stress. The load-carrying capacity of this pillar was lost before most of the primary stopes had been filled, causing stresses to arch to the abutments. This was verified by very small stress changes in the readings of the backfill instruments. Two-dimensional, finite-element analyses of the B-Neath orebody predicted failure zones at the same locations as those identified by the rock instruments, but the linear correlation between the relative displacements in the rock and the relative displacements predicted by the numeric model was only 0,24. The model predicted gravity stresses in the backfill, but the statistical correlation was small for the measured and predicted displacements. This work will further the Bureau's goal of maximizing resource recovery by validating backfill design, evaluating mine stability through the use of numeric techniques, and improving the design of backfill instruments.
Mining; Mining industry; Underground mines; Underground mining; Rock mechanics
D.R. Tesarik, U.S. Bureau of Mines, Spokane, USA
Minefill 1993: The 5th International Symposium on Mining with Backfill, June 7-9, 1983, Lulea, South Africa