Studying On Deformation Mechanism And Support Technology Of Extremely Fractured Coal-rock Roadway With Large Deformation

At prenst, it has become the most complicated problems in underground roadway engineering to control the stability of soft rock roadway with complex conditions, as seroursely restricted the level of high yield, high efficiency, low consumption and safety production, and the healthy and sustainable development in mine mining. In the process of underground mining in China coal mines,there has a lot of soft rock roadway, and its geological conditions of surrounding rock is quite complicated, especially extremely fractured coal-rock roadway with the complicated and changeable environment of surrounding rock structure, hydraulic properties and stress distribution. As a result, it leads to the diversity of failure mechanism in the roadway and furthermore, to coal-rock roadway in specific geological conditions, the research conditions and emphasis on the surrounding rock failure mechanism and supporting control theory was not the same everywhere. Therefore, it is significant and has practical value to explor the failure mechanism of this type of roadway for the stability of surrounding rock failure.In this paper, haulage gate of 11301 fully mechanized coal face in Mukong coal mine was studied, the deformation and failure mechanism of the surrounding rock was systematically analyzed on the basis of occurrence characteristics of surrounding rock, and the effective controlling countermeasures and optimal supporting scheme to maintain the stability of the roadway was put forward by using the combination method of field investigation, laboratory test, theoretical analysis, numerical simulation and field test. To summarize, the main work are focus on the following aspects:(1) Based on the measured results and field survey, mine geological data, rock column and the section supporting form and parameters was retrieved in haulage gate of 11301 fully mechanized coal face. Under the condition of the original support, the failure characteristics of surrounding rock are summarized by investigating the deformation and failure conditions of surrounding rock and the damage condition of supporting structure, and probing the status of fracture growth inside surrounding rock.(2) In the light of haulage gate of 11301 fully mechanized coal face, a series of basic laboratory tests, including X ray diffraction test, point load strength test, rock disintegration test and so on, was done separately to respectively proved the fractures situation of internal surrounding rock, the rock mineral composition, mechanics strength and water physical properties of surrounding rock, which laid the groundwork for determining the roadway support scheme.(3) According to various factors of the deformation of surrounding rock, mechanical instability model on roof and two sides of the roadway was established. At the same time, Combined with the serious floor heave phenomenon happening in roadway floor, the mechanical instability mechanism and insibility criterion of surrounding rock, and the estimation formula to estimate the floor heave were obtained in the original supporting structure.(4) On the basis of control countermeasures for surrounding rock of the broken and extremerely unstable roadway and the superposition compression arch theory, combined support scheme with "Long and Short cables" as the main body was put forward. At the same time, FLAC 3D numerical calculation was used to reseach the support effect of various combination schemes obtained by orthogonal test method. In addition, the convergency, displacement condition and stress distribution of surrounding rock under the conditions of the worst supporting scheme and the optimal supporting scheme were compreded and anaslyzed respectively so as to come to conclusion.(5) In the light of the actual situation of 11202 return airflow roadway, the best supporting scheme and its parameters proposed by numerical optimization was applied to the roadway. And the convergence deformation status of roadway surrounding rock and the stress condition of anchor were monitored for 6 months, and what was more, the support effect was verified and evaluated according to the monitoring data.