Analysis On Failure Modes Of Complex Mined-out Area And Research On Governance

There are a large number of untreated mined-out areas in China’s underground mines.When the volume of areas reaches a certain size,it is hard to ensure the stability of mined-out area,mined-out areas will be destroyed,which even induces the surface collapsing,and causes accidents in mines.The destruction of mined-out areas brings great influence to people’s life,meanwhile leaves huge hidden trouble for mining engineering in the future.In order to study the damage reasons of goaf roof,the determination of safety mining size and how to safety treat mined-out area,this paper took Tanyaokou goaf in Nei Monggol as an example and made the following several aspects of research:Firstly,this paper determines rock mechanics parameters by field drilling sampling,and comprehensively evaluates the engineering geological conditions of ledge and surrounding rock.Geophysical methods proved again the size and occurrence location of goaf,which provides a reference basis for mechanical model and numerical simulation analysis.Secondly,Possible failure modes of roof,failure conditions and characteristics for failure modes are researched.The relationship between the roof deflection and load,thickness,span parameters is given based on the mechanics of elasticity and the first strength theory.This paper studies the three mechanics models of goaf roof and evaluates roof stability combined with the example of Tanyaokou mined-out area.Then,establishing the different numerical models analyses the effect of mining span or roof thickness on the stability of mined-out area based on particle flow method,and the effect of mined-out areas each other.On the basis of simulation,the determination method of safety mining span in the mined-out areas under different roof thickness is putted forward,which defines the safety mining spans under different roof thickness combined with the simulation analysis of Tanyaokou goaf in Nei Monggol.The equation can provide theoretical support for safety mining of the ore bodies at the next stage.Finally,the four categories of governance method(sealing method,blasting method,filling method,reinforcement method)are studied about Metal mined-out area,and their applicable conditions.Combined with the status of Tanyaokou goaf,different treatment solutions are put forward.The method of partition grouting and filling reinforcement is determined through the comparison.The stability of goaf after reinforcement is evaluated by drilling sample and simulating excavation of section 1150 orebody.