Review And Design Concept For Grouted Multi-Jacketted Friction Balancing Rock Bolt
Peter R K Chileshe
Index Terms: Friction, grout, grouted rock bolt, jacketted rock bolt, load, load balancing, rock bolt, stress abutment, stress-strain, Zambia.
Abstract: Rock is under greater abutment stress and strain on the sidewall periphery of an excavation than deeper in the rock, especially in the immediate aftermath of mining. If some mechanism could be actuated where a grouted rock bolt was able to transfer excess strain energy from the highly stressed section in the sidewall along its length to the deeper part, the load along its length would be balanced or equalised through friction. The result would be increased effective rock bolt anchorage length, reduced rock yield in the sidewall, and lessened grout and/or bolt failure. The paper reviews grouted rock bolts and proposes the conceptual grouted ‘Multi-jacketted Rock Bolt’, as one route that could be employed in achieving frictional load balancing along the axis of the grouted rock bolt, with six variations proposed. The ‘Jacketted Rock Bolt’, would be an assemblage of tubular steel jackets, concentrically fitted within each other. As excavations are mined and rock bolted, friction would be generated between ‘jackets’ in grouted jacketted rock bolts, in response to movement in the surrounding grout and or rock mass. This would transmit frictional energy from one jacket to the other in a frictional balancing system. This is conceptual.
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