Novel Underhand Cut-and-Fill Stoping Method and Mechanical Analysis of Overlying Backfill

Underhand cut-and-fill stoping is an efficient, sustainable mining method that is particularly applicable to complicated mining conditions in which both the peripheral rocks and the orebody are extremely unstable. Considering the mining conditions of the shallow, steeply dipping, narrow orebody in the Canzhuang gold mine in Shandong Province, China, a new method of underhand cut-and-fill without sublevel stoping that does not use the conventional sublevel, access to stope, and decline is proposed. Additionally, a novel auxiliary ventilation mode is applied to achieve high-efficiency ventilation. The restrained-beam mechanical model is established for the overlying backfill in single drift to ensure stability of the test stope. The plane problem is transformed into a three-dimensional problem when deducing the theoretical evenly distributed load of the overlying backfill. The optimal bearing layer thickness of the overlying backfill is calculated. During a 2-year field industrial test, the ore dilution ratio reduced from 14 to 4% and the ore recovery ratio increased from 75 to 92%, which improved the economic efficiency significantly and satisfied safe-production requirements. The description of the new mining method might provide theoretical and practical guidance for mining in similar settings.