| With the process of coal mining,its need some coal pillar to maintain the stability of the roadway and roof,but it can't deny the coal pillar “the root of all evil”.Goaf pillar can be cause the roof to the surface on the uneven settlement,the floor stress under non-uniform distribution.And the stress concentration of the pillar has obvious influence on the lower coal seam.When the thick coal seam with overlying mined-out area between layers of 30 ~ 80 m,for the average working face,for the general working face,it is have't obvious effect.However,the impact of more that 14 m the large coal seam is more significant.Overlying goaf rock mass in a wide range of excavated with coal seam mining,if the interlayer rock bearing capacity is not strong,the load in some form cataclastic structure and function in the bedrock.When the bedrock is can't be form the structure,the upper and lower part of the zone is fully connected with the each other,resulting in the occurrence of the overall cut and falling pressure of the working face.The concentrated stress of the pillar increases the occurrence of the pressure frame accident.Based on 13 # coal seam of xiegou coal mine as engineering background,comprehensive analysis of the theoretical,numerical simulation,similaritysimulation and experimental methods,research on moving laws of coal rock affected by the deformation andmigration characteristics of hollow rock and pillar of coal,dynamic analysis the process of instability of coal and rock and seek the conditiono f coal strata and structure formation and instability to control the coal and rock dynamic disasters,exploring the conditions of the coal column in the upper zone and the whole thickness of the lower zone,and establishes the corresponding criterion to analyzing and determined the resistance of the support.Get the following conclusion:(1)8 # coal seam in mined-out area are mainly composed of coal exist on both sides.The coal pillar had a greater influence on the fioor.On the roof load,the impact of the coal pillar will cause deformation and destruction until the stability will lost.Based on the limitation load,rheological properties and mutation theory of coal pillar,the limit width of coal pillar is 8.9 m.When the coal pillar less than the limit width,its will failure completely;when it greater than the limit width,it will be produce stress concentration.Through theoretical analysis,and established different corresponding mechanical model,research the stress concentration under coal pillar bottom stress spread and damage depth.(2)Study the principle of mining pressure in the thick coal seam.Analyze the crushing and falling characteristics of the initial and period pressure,give the calculating formula of break distance.At the same time,the critical layer is used to determine the key layers of the coal mine.Using theoretical analysis,Qualitative analysis is carried out on the destruction of the direct roof and the basic roof..(3)The lower strata of the coal pillar in the mine area are 55 m with working face,the whole cutting and falling of the rock in the coal pillar stage can cause the disaster such as the pressure frame of the working face?The floor strata structure destruction and movement influenced by parameter of pillar width,pillar density and spacing of coal pillar.The more coal pillar width,the greater the degree of impact on the floor strata and regional.For coal seamunder the condition of double coal pillar,spacing within a certain range,can be considered as a whole coal pillar;When coal pillar spacing is equal to a value,it will appear a critical point,strata structure is decided by more width on one side of the coal pillar;When coal pillar spacing is greater than a certain value,the formation of independent influence area.At the same time,according to the results of simulation and experiment,set up the mechanics model,the judging criteria are put forward on the crushing mechanism,and to predict the coal pillar impacted width.(4)The problem of the pressure frame of a variety working face is 55 m,which is mainly concentrated in the area of the mining area and the position of the coal pillar.Through established different structure model of surrounding rock under the condition of support,analyses the special thick coal seam mining under the coal crushing mechanism,received reasonable support resistance calculation method.The research indicates that the support need 27766.4 KN resistance to ensure the safety and stability of the quarry.Existing support is difficult to satisfy such a large working resistance,traditional only by speeding up working face advancing speed and blasting is an effective treatment measures to solve face crushing coal pillar.(5)The method of blasting coal column or controlling rock in deep hole is proposed,the method of change of surrounding rock by active structure to ensure the stability of stope surrounding rock,and preliminary validation by means of numerical simulation. |
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