Development of strata movement and its control in underground mining: In memory of 40 years of Voussoir Beam Theory proposed by Academician Minggao Qian

Abstract

Since widely accepted by international scholars, Voussoir Beam Theory proposed by Academician Minggao Qian helps the research on underground mining pressure realize leapfrog development from the stage of qualitative hypothesis to quantitative analysis. In the past forty years, an integral system has been formed for strata movement theory and strata control technique, contributing to safe, efficient and green mining of underground coal seams. By underlining the voussoir beam theory, critical developments on strata movement and its control have been reviewed. Important topics are proposed for future research. In the voussoir beam theory, rupture characteristics of main roof are studied with beam and thin plate models. It is revealed fracturing line of main roof locates ahead of the longwall face. Due to supporting effects provided by coal wall and caving materials, the rotation of broken blocks of main roof results in the occurrence of compressive force, forming the voussoir beam structure. Both slipping and rotating instability modes of the structure are identified. The S-R instability conditions are determined. Based on such understanding, determination method for roof load is proposed through keeping the balance of voussoir beam structure, realizing quantitative analysis on the relation between hydraulic support and surrounding rock. Until now, the voussoir beam structure stands as the most impeccable model for explaining underground mining pressure. It is a major breakthrough for conventional qualitative hypothesis, which makes historic contributions to living safety and working efficiency of the miners. The Voussoir Beam Theory further brings about many achievements on strata control, including three-coupling relation between hydraulic support and surrounding rock, dynamic load model for roof control, medium plate model, far-near field model in longwall face with large space etc. Based on the voussoir beam theory, the key stratum theory is moreover proposed by Minggao Qian in the middle of the 1990s. Mechanical relation between different overburden strata is established during movement process. Coordinative analysis on mining pressure, strata movement and surface subsidence is realized. The Voussoir Beam Theory and key stratum theory provide significant guidance on the research of coal mining pressure and strata movement, contributing to a series of theoretical developments, such as mining pressure control at the face area, mining induced fracture distribution in strata, mining induced stress distribution, strata movement and surface subsidence. Such achievements serve as the foundation of green mining and scientific mining. Further development of the theory should pay attention to unified field theory for strata movement, strata movement based accident and damage prevention technique, strata movement under complex mining conditions, visualization of strata movement and intelligent strata control.

Keywords

• strata movement
• voussoir beam theory
• key stratum theory
• strata control
• longwall face