A Comparison Between Empirical and Numerical Methods in Underground Galleries Support System Design

摘要

Tunnels and galleries are the most important structures in coal mines. They are used for variety of purposes, such as transporting ore and people and for ventilation. A well-designed support system is necessary to stabilize structures and prevent collapse. Using rock bolts increases the strength of the rock in which tunnels are made. Rock bolts are used extensively in most underground mines today, and coal mines are no exception. Almost all galleries in a typical coal mine use some type of rock bolt, at least, as a means of partial or supplementary support. In this research, changing the support system from expensive methods to the use of rock bolts as the primary means of support is discussed, with the focus on a particular gallery in Hejdak coal mine. Visionary design methods, in conjunction with rock mass classification schedules, were used to determine an optimal rock bolt pattern. For this purpose, rock mass rating (RMR) and quality index (Q) classification systems were used. Several empirical methods were also used to design an optimal pattern for rock bolt installation in the particular tunnel under analysis. As such, the tunnel support system was designed using both finite element and empirical methods. Finally, the results obtained from both numerical and empirical methods were compared under different load conditions. The methodology prescribed in this paper, together with the comparison, can be a useful tool when selecting a support system. The results can also be used to design a support system in this and any other coal mine with similar conditions.