Advancement of Conventional Anchor Support System through Use of NATM and NMT Approach for Underground Drift Stability

Abstract

In present scenario underground mines of Central India is using conventional supporting with anchoring/bolting
system to supports the excavated haulage road and cross cut. In case of geologically disturbed areas concreting
with girders is the main support. In routine formations short bolts suffice the purpose. These conventional
methods specially concreting is time consuming and hampers productivity. Application of NMT (Novergian
Method of Tunneling) and NATM (New Austrian tunneling method) will give the advancement in the support
system. Application of both the method will reduce support erecting time and thus the cyclic operation of
mining can be accelerated. The cross-section area of Under drift will 6m x 3m, 4 m x 3 m, 3m x 3, etc.
Conventional concrete support for the area may have required 15 days (5 R-mt span). The same was done by
shotcreating with NATM/NMT in just 5 days (5 R-mt span) including lowering of machine and materials.In
geologically stable formations applicationof long bolt, short bolt, and anchorage through cable was found to
provide requisite support tothe excavated drift.Rock Mass Rating of Bieniawskiand Barton’s Q system support
calculation methods have been used to calculate support requirementsfor haulage as well as cross cut drifts.