Research On The Spatial Characteristics And Governance Process Management Of Underground Coal Fire

Underground coal fire is a phenomenon of coal spontaneous combustion formeda certain scale and having a certain impact on the environment. Pores among fallingrocks, overlying rock fissures and surface cracks are the passageways for supplyingair and dissipating gas and heat, are the important factors influencing coal-oxygencomplex, regenerative heating and high temperature combustion, and determine thegas concentration field, flow and temperature distribution of the combustion space.Therefore, researching on the law of distribution and variation of voidage inunderground coal fire is very important to grasp the transfer law of heat and mass inits occurrence and development processes.Based on the "Masonry beam" mechanical model of rock mass structure, rockbreaking theory of plate and the theory of random media movement, this paperconstructs a model of spatial distribution of voidage in the space of underground coalfire. This model includes continuous and discrete non-homogeneous distributionmodel of pores among falling rocks, vertical discontinuous, anisotropic, andinhomogeneous distribution model of overlying rock fissures composed ofdelamination cracks and broken fissures, and random medium statistical model ofsurface cracks. Moreover this paper reveals the distribution and dynamics law ofvoidage in the space of underground coal. Combined with case study，we found thefollowing conclusions. i) In the shallow part and edge area of the combustion goaf,Voidage of pores among falling rocks, overlying rock fissures and surface cracks havethe maximum values and coal fire often occurs here, but in the middle region, voidagehave the minimum values. ii) In the shallow part and edge area of the combustiongoaf, broken fissures are in main place among overlying rock fissures, but in themiddle region delamination cracks are in main place. iii) Since the sinking of theoverlying rocks has incompatibility, the vertical cutoff point of the change of voidagewill appear in the middle region of the combustion goaf. iv) Cracks that has been fullydeveloped exhibit a negative exponential decay over time and the decay rate increasesalong with the increase in coal burning velocity. v) With the coal combustion, thesurface cracks parallel with the development direction of the combustion extend alongthe development direction of the combustion, and the surface cracks perpendicular tothe development direction of the combustion gradually close and regenerate.This paper presents a rough calculation method of the pace of development of underground coal fire based on the plastic yielding theory of coal, thermal gravimetricanalysis(TGA) techniques and dynamics theory of combustion reaction. The pace ofdevelopment of the Anjihai Fire District in Kuitun is0.16m/d.This paper builds a management system based on PDCA cycle used for thegovernance of underground coal fire. This system includes the development status andtrend analysis of fire district using a FAHP, control technology optimization ofunderground coal fire based on AHP, evaluation of fire extinguishing effect based onthe fuzzy comprehensive evaluation method and improvement of scheme based on thefault tree analysis(FTA). The controlled circulation and successive improvement ofthe design, implementation, evaluation and improvement of governance program hadbeen achieved.