Key technology and application of small-sized full-section boring machine for rapid construction

The production of coal mines is strongly affected by the excavation efficiency of rock roadways. Compared with the traditional drilling-blasting method and the fully-mechanized heading machine method, the shield machine method has significant advantages in terms of excavating efficiency and has been gradually applied in coal mine rock roadways. However, the diameter shield machine generally exceeds 5 m, which can hardly be applied to small section rock roadways. To increase the advancing speed of small-section rock roadways, a small-sized (ϕ=3.5 m) full-section boring machine was developed considering comprehensive factors such as shaft cage lifting, equipment capacity, roadway size, gas control mode, equipment explosion-proof performance, continuous gangue discharge, and roadway construction conditions. Based on the engineering geological conditions, numerical simulation was conducted, and the optimal support parameters under the conditions of sandstone, sandy mudstone and mudstone roof were proposed. The goal of “stable surrounding rock control, accurate number of support materials, and short support time” were realized. Further, a series of auxiliary techniques were developed to deal with problems encountered in the field application. The steel bar self-networking technique was developed, and super long belt conveyor was applied to increase the slope range（−9°−+9°）of the whole machine. Besides, the cutter head cooling water circulation system was improved, and advanced fault management technology was developed. The research results show that the excavation efficiency rock roadways is significantly affected by continuous gangue discharge system, shield machine operation line equipment configuration, rapid launch and removal technology, precise roadway support construction and labor organization. The small-sized Full-section Boring Machine and rapid construction technology are applied to the return air roadway of the east boundary of Guqiao CoalMine. The application results show that the new small-sized boring machine completed excavation of 3 115 m long roadway within 7 months, and break the excavation construction record of the rock roadway in the Huainan mining area with a monthly footage of 600.6 m. The excavating efficiency is increased to 3.15 times that of the drilling and blasting method, and the per capita work efficiency is increased to 3.82 times that of the drilling and blasting method.