| Nowadays, rock pressure monitoring data, on the basis of determination of mechanical properties of surrounding rock in the domestic, assisted by the system of mining roadway optimization design, is increasingly valued. Observing the law of mining pressure appearance in mining area not only guarantees the working face production safety, but also can verify the working face support selection, and optimize the up and down along the trough of roadway supporting technology. Therefore, carrying out the large mining height coal mining key technology research, as well as the initial mining working face in mine roadway surrounding rock physical mechanics test and stope drift mine pressure monitoring, to improve the rationality of the design of roadway support, to ensure the safety of roadway, reduce support costs and achieve high yield and high efficiency, is of great significance. At the same time, it will make important engineering guide value for the guarantee of our country’s coal industry sustainable and safe development, and ensure the security of energy supply.The Wang jialing coal mine in Shanxi Coal Transportation Group Co. Ltd. is a new project, located in south of Baode County, Shanxi Province and in northern Hedong coalfield. It belongs to one of the six major projects in the industrial park of circular economy in Baode, it is an important supporting project of Shanxi coal transportation group key construction development and transition project. As a new mine, it lack of experience in the design, construction and other aspects. On the one hand, the lack of relevant data of coal and rock mass characteristics caused the basis for selection of parameters missing in the design of roadway surrounding rock supporting scheme, on the other hand, the lack of the measured data of the mine pressure, makes the work surface support selection, the design of the supporting roadway surrounding rock supporting the load can not be accurately calculated. In the actual production process, the movement of the roof and the law of the mine pressure and the corresponding control technology will occur a few new problems, so it is necessary to make the specific research of the specific conditions.This paper is based on the technical problems of the mining progress facing of the first coal mining face in the Wang jialing coal mine, researching on the technology of pressure monitoring and surrounding rock control in the first mining face, through the analysis of mine pressure monitoring data, a systematic study on the law of the mine pressure and the pressure of the roadway is carried out; combining the physical and mechanical parameters of coal rock and geological structure characteristics, the characteristics of surrounding rock movement are obtained, and the basic data of mine pressure data is constructed. The results are used in the design and verification of the control parameters of the surrounding rock; based on the analysis of mine pressure data in the working face and grasping the law of roof movement, analyzing of the rationality of the scaffold, the optimization scheme of frame selection is put forward; analysis of the rationality of the working surface length in the existing mining conditions from mine pressure; through field monitoring data analysis and feedback, combined with the surrounding rock deformation law and the law of stope mining pressure, the reasonable supporting form and parameters of the roadway and the reasonable size of coal pillar are obtained, providing guarantee for continuous, safe and efficient mining in mining area. The achievements of the paper mainly contain the following five aspects:1. The physical and mechanical parameters, such as elastic modulus, Poisson ratio, compressive strength, tensile strength, cohesive force and friction angle of the rock, are provided by the single axis, three axis and Brazil split test, providing basis for roadway support, at the same time, according to the XRD and SEM experiment, it can be known that quartz is the main mineral in the coal seam, and the main mineral components are clay minerals, it reflects the strength of the coal seam in the Wang jialing coal mine, but has large expansion.The clay minerals content of roof rock sample quartz is as high as 39.5%,the total amount of clay minerals is 54.2%, the structure of the direct roof mudstone is relatively loose, and the whole mass is a lump, and the porosity is large, the rock is easy to expand and collapse contacting with water. Therefore, designing roadway support must take into account the waterproof measures of surrounding rock.2. From the analysis of resistance of the whole working face pressure, it has the characteristics of the middle smaller, both sides slightly higher, the resistance of the end and head and the adjacent parts has frequently fluctuated,support resistance should be maintained at around 40 MPa, with the increase of mining height, the roof will be more full movement, support working resistance distributes more uniform, with the increase of mining height, the pressure step distance of the roof is reduced, and the pressure duration is increased. The load distribution law of overburden strata increases with the increase of mining height, and the load distribution law is large in the middle of the working area, and the two ends are small. the load of overlying strata has increase trend with the increase of mining height. The number of roof falling down in the initial stage of mining is increasing, the load of the working surface is increasing, and the strength of the scaffold is increasing; the stress concentration factor of the working surface decreases with the increase of mining height, and increases with the increase of the number of roof falling down. The larger mining height working face length is, the greater work resistance is. To accelerate the speed of the mining face, the pressure of the face is weakened, and the pressure of the period increases, it is conducive to the production of roof management.3. The geological exploration of the rock breaking range of the roadway is carried out by using the borehole peep at the roof and two sides of the roadway and the belt lane, respectively,in the belt lane,The maximum loosening range occurs in the vicinity of the intersection of the tangent and the roadway, where shows the phenomenon of multi layer loosening, the farther the distance from the cut is, the less the number of the loose circle is, and the loose range also shows the trend of narrowing, but closing to the end of the head position, it is subjected to stress concentration, closing to the cracks in the coal wall is more development, where need to strengthen the support of both ends of the head.4. Through theoretical calculation and engineering analogy analysis of Wang jialing coal mine caving support reasonable supporting parameters: select the ZF16000/23/43 D type caving coal hydraulic support, design initial support force 12818kN(P=31.5MPa), working resistance 16000kN(P=39.3MPa), support intensity of 1.5 ~ 1.55 MPa, the center distance of 1.75 m(width), width of 1.66 ~ 1.86 M; according to the actual working surface of the test stand and the actual production needs of the next working surface, although the current bracket has a certain margin, the frame type does not do the optimization.5. Similar simulation and numerical simulation results show that the large mining height working face roof falled down to a wide range, after mining, the roof caving directly affects the surface. The overlying strata basically take the caving zone and the fracture zone, and no bending subsidence. Due to the thickness of the roof load layer, the old roof rock mass is not easy to form a stable masonry structure. The roof has obvious characteristics of breaking the slab, the displacement of the mining face is large, and the two ends are small. Research on the influence of the length of the working surface on the law of the overlying strata movement shows: when working face length is not the same, regardless of the working surface, the displacement value of the monitoring points increases with the increase of working surface width. Research on the law of the high- and- covered rock movement in the working face shows: the movement of overlying strata increased linearly with the increase of mining height. Research on the velocity and the law of the overlying strata movement shows: the displacement of the overlying strata decreases with the increase of the speed.6. According to theoretical analysis and numerical simulation, the first working face setting up to 20 ~ 25 m coal pillar is more reasonable. At the same time, on the basis of the analysis of the law of the large mining height working surface mine pressure, reasonable selection of hydraulic support for working face, research on the key technology of improving coal resource recovery rate based on the reasonable length of the working face and the selection of coal mining equipment, field implementation effect is good. |
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