| Based on the engineering background of Double-roadway layout face in Gaohe Coal Mine,through UDEC-Trigon numerical simulation method,the characteristics of internal stress,crack expansion and surrounding rock deformation of pillar width in different sections during Double-roadway excavation and two working faces were studied.The reasonable section pillar width of Double-roadway layout face was obtained,and the bolt(cable)support of W1310 return air chute was determined.The parameters have been successfully applied in the engineering practice of Gaohe Coal Mine.The main research results are as follows:(1)The compressive strength,tensile strength and shear strength of coal and rock samples in Gaohe Coal Mine are determined by testing the mechanical parameters of rock mass in laboratory.In order to make the rock mass parameters in Trigon model as close as possible to the actual parameters of physical problems,the rock mass parameters obtained from laboratory tests are modified,and the theoretical values of the rock mass parameters are obtained.The uniaxial compression of the above-determined stratification parameters is carried out.The shrinkage test verifies the rationality of the micro-mechanical parameters of rock mass.(2)Based on the limit equilibrium theory,the theoretical width of coal pillars in double roadway driving section should be more than 4.97 m.The UDEC-Trigon model is used to analyze the load-bearing characteristics of coal pillars during full dynamic pressure process.During excavation,when the width of coal pillars is 5m,the peak vertical stress in coal pillars is 6 MPa,the shear cracks in coal pillars are connected with each other,and the deformation of roadway surrounding rock is large,and the coal pillars in this section are in yield.During the mining period of W 1309 working face,when the width of coal pillar is 7 m,the peak value of vertical stress in coal pillar is 8 MPa,the shear cracks in coal pillar penetrate each other,the surrounding rock is deformed greatly,and the coal pillar is in the yield bearing state;when the width of coal pillar is 15-20 m,the coal pillar is in the stress increasing area and the vertical stress peak in coal pillar is affected by the superposition of lateral supporting pressure in goaf area.The value increases sharply,and there are crack closure areas in the coal pillar,but the shear and tensile cracks in the coal pillar appear asymmetrical distribution law,the deformation of surrounding rock also appears obvious asymmetry,and the coal pillar is not easy to maintain stability;during the second mining period,the bearing capacity of the 12 m coal pillar in the plastic bearing state is better and easy to maintain stability during the second mining period.Finally,the width of coal pillar in double roadway driving section is determined to be 12.0 m.(3)The roof bolt of W1310 air intake groove is 22 mm × 2200 mm left-handed threaded steel bolt with spacing and row spacing of 800 mm × 900 mm respectively.The roof bolt is reinforced by mine bolt cable with spacing of 21.6 mm × 6300 mm The side bolts are made of 20 × 2200 mm left-handed threaded steel bolts with a row spacing of 800 mm × 900 mm,and the pillar walls are strengthened with 21.6 mm × 4300 mm mine anchor cables,which are arranged in three patterns.Field industrial test was carried out in W1310 air intake chute of Gaohe Coal Mine.The results show that the maximum deformation of roof,floor and two sides of roadway is 375 mm and 480 mm respectively during the second mining period.After the first mining stabilization,the maximum stress value of 6 m position in the middle of coal pillar is 14 MPa.When the mining advance is 30 m,the maximum stress value of 6 m position in the middle of coal pillar is 16 MPa,indicating that the 12 m section.Coal pillars have good bearing capacity in the process of full dynamic pressure,and the surrounding rock of roadway is easy to maintain stability.There are 47 Figures,9 Tables and 54 References... |
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