Room And Pillar Ground Control Utilizing The Grouted Reinforcing Bar System (23a44feb-2dae-491f-860f-4e5cb6457e92)

This paper was presented at the ‘17th U. S. Symposium on Rock Mechanics’ on August 29, 1976, at Snowbird, Utah, at the SME-AIME Fall Meeting on September 1, 1976, at Denver, Colorado, and at the Polish-American conference on Ground Control in Room-and-Pillar Mining on August 7, 1980 at Southern Illinois University, Carbondale, Illinois. Introduction The purpose of this paper is to present a viable method of reinforcing rock pillars by utilizing fully grouted reinforcing steel and a cement- fly ash mortar. Although the fully bonded bolt concept is not new as exemplified by the present widespread use of resin bolts within United States mines and by the use of cement grouted reinforcing used as back pins in the Kiruna Iron Ore Mine in northern Sweden, (1)(2)the method of stabilizing mine pillars with fully bonded reinforcing is new. This method, called the "grout-rebar system", was first incorporated at St. Joe Minerals Corporation's Fletcher Mine in December of 1972. The system was used on an emergency basis before extensive research on the mechanics of the system could be completed. Since Decmeber of 1972, however, approximately 206 pillars have been reinforced at Fletcher and the system is currently being used on a regular basis at two other St. Joe mines and at two competitor mines in the area. Basically, this paper is a case study of the efforts, research and results of utilizing the grout-rebar system, on a selective basis, at the Fletcher Mine. In addition to information about the system, this paper will explain in detail the three rock mechanics instruments developed by St. Joe and used to measure and monitor rock movement to validate the group-rebar system.