Industrial test on prevention of mine-shaft failure using low-pressure water injection

Abstract

Due to the problem of stress elastic rapid rise of the borehole wall and strain of borehole wall increase when high pressure water injection was stopped, the ventilation shaft of Jining No.3 coal mine was taken as example, through theoretical analysis, industrial experimental of Z5, Z6 hole water injection combined with low pressure, to explore the feasibility of the two hole joint injection, and water level variation with time of the water level observation hole, strain state of alluvial strata and shaft wall strain before and after water injection were analyzed.The results show that Qunder-3, Z1 hole water level increased significantly by 3.67 m and 4.16 m;Qunder-1、Qunder-4 hole water level rise was relatively small by 1.03 m and 1.77 m.After injection, the water level decreased significantly;24th, 29th, 32nd, 34th alluvial strata strain and corresponding Z1 hole water level fluctuation were synchronous, and 38th strata strain and corresponding Qunder-3 hole water level variation without synchronization was related to strata in the vicinity of alluvium and bedrock related interface;Water injection had a significant effect on ventilation shaft vertical Strain, Qunder-3 hole water level each uplift 1m, the vertical microstrain of the corresponding shaft 172 m level 52V-1, 53V-1 average increased 1.54 and 15.23;Ventilation shaft 172 m level vertical strain variables and the corresponding Qunder-3 hole water level variation was linear correlation, could provide a basis for simple judgment shaft wall strain state.

Keywords

• shaft
• low pressure water injection
• water level
• alluvial strata
• strain