Study On Failure Evolution Mechanism And Control Of Roadway Driving Along Next Goaf In Fully Mechanized Top Coal Caving Face In Kilometer Deep Mine

This thesis regards roadway driving along next goaf of fully mechanized caving in deep mining as research object, the deformation and failure characteristics of surrounding rock of roadway driving along next goaf of fully mechanized caving in deep mining was researched by using the research methods of laboratory test, field detection, numerical simulation, geological mechanical model test and theoretical analysis, on this basis, analyzing the stress and displacement evolution mechanism of the surrounding rock of roadways, the deformation and failure mechanism of surrounding rock under the condition of different coal pillar width was revealed, based on the mechanical analysis model of surrounding rock of roadway sides of driving along next goaf in deep mining, deriving the formula of the coal limit equilibrium zone width and stress displacement of surrounding rock, and combining the methods of engineering analogy and the numerical simulation optimization, proposing a method for confirming the coal pillar width of roadway driving along next gob of fully mechanized caving in deep mining, according to the deformation and failure characteristics of surrounding rock, and getting the corresponding control countermeasures. The main conclusions drawn from the thesis are that:(1) Deformation and failure characteristics of surrounding rock of roadway driving along next goaf of fully mechanized caving was defined, including remarkable deformation and creep properties of surrounding rock, the range of damaged beyond anchorage zones, the supporting component was fractured seriously, and the position of lateral stress peak is significantly greater than the shallow coal mines, etc., The main reasons of deformation and failure characteristics of surrounding rock of roadway driving along gob of fully mechanized caving was revealed, stress environment of roadway surrounding rock is complex, supporting parameters selection is not reasonable, and roadway section size is large, etc.. Then, analyzing stress distribution of surrounding rock influenced by the coal pillar width, section size, embedded depth of coal seam, and the thick coal seam through the numerical simulation, the characteristics of surrounding rock was clarified.(2)The model of roadway driving along gob of fully mechanized caving has been carried out, surrounding rock stress, displacement evolution mechanism and distribution characteristics have been studied under the condition of different coal pillar width, the surrounding rock deformation and failure mechanism in fully-mechanized caving deep roadway driving along gob was revealed.(3)Considering strength softening characteristics of coal pillar and the interface of coal roof and floor, the mechanics analysis model of entity coal pillar and deep roadway coal pillar driving along gob was established, getting calculation formula of the limit equilibrium zone width and the stress and displacement of coal pillar theory, discussing the influence of the depth of coal seam, roadway height, shear stress softening coefficient, interface mechanical parameters and other factors on the limit equilibrium zone width of coal, surrounding rock stress and displacement distribution. Those provide an important theoretical support for design and construction.(4)Based on the theory of limit stress equilibrium zone width calculation, considering geological conditions, stress environment, structure demand and other factors, combined with engineering analogy and numerical simulation optimization method, this paper proposes a determination method of coal pillar width in fully-mechanized caving deep roadway driving along gob. According to this method, relying on specific engineering example of Zhaolou coal mining, the reasonable coal pillar width in fully-mechanized caving deep roadway driving along gob under the similar geological conditions was determined.(5)The characteristic of lead abutment pressure distribution on the deep well fully-mechanized caving face has been analyzed systematically and accurately by method of combining stress online and microseismic monitoring technology, and the opinion that face push mining process can be divided into four stages which are early mining stage of face, "first square" stage of face, normal working stage of face and "second square" stage of face was put forward in order to analyze the characteristic of lead abutment pressure distribution, designing more reasonable advancing supporting distance during the period of mining face and providing on-site measured data.(6)Field application results show that the coal pillar width of the eleventh mining area’s fully-mechanized caving roadway driving along gob of Zhaolou coal mine called kilometer’s deep well should be five meters, and the control effect of roadway surrounding rock can meet the requirement of normal production of working face when using "metal net on the roof, longitudinal steel belt adding ladder metal net on the two side, longitudinal reinforcement ladder adding anchor cable reinforcement and shotcrete on the side of narrow coal pillar adding borehole pressure relief strengthening support on the side of entity coal and combined support technology of sizing block reinforcement on the surrounding rock during mining face" during the period of roadway driving along gob, effectively solving the problem of deep well fully-mechanized caving roadway driving along gob supporting technology, the results of the study provides useful reference for similar roadways which are complex and difficult for supporting.