| The conditions of roadway in Tunlan coal mine is typical combined roof, there is several mudstone interlayers consisting in roof strata. The type of mudstone interlayer is thickness-uneven, fracture joint development, low intensity. This mudstone interlayer cut apart continunity of the roof strata and have caused several roof fall accidents in the process of mining. So how to design reasonable support scheme is problem demanding prompt solution. Meanwhile, the solution will provide a certain reference on combined roof support technology and support mechanism in complex conditions. This paperi's main research content is as follows:1. Rock breaking mechanism of roadway roof(1) Mechanical structure of coal roadway roof strata is divided into plate structure and beam structure, we analyze the structure of coal roadway roof rock breaking mechanism on board structure model and beam structure model, board structure model make subjected to a uniform load of simply supported plate as an example, Beam structure is divided into Charpy and clamped beam and analysis of the mechanical breaking mechanism;(2) Identified the factors of stability about roof rock: Influence coefficient for mining in working face, Depth impact factor, Stress Abnormal impact factor, Rock integrity influence coefficient, Coefficient of rock mass strength, Structural factors and the groundwater has a great influence on the stability of rock, but can not be quantified,it will be considered at the level of roof hidden chapter of the divided;(3) Using multivariate single indicator methods to determine the stability of thick rock, when rock steady, its stability is greater than the span of the roadway span.2. Roadway structure, mechanical properties and petrography(1)Through analysis of roadway roof boreholes and core materials, structural characteristics of surrounding rock in roadway can be drawn:?Roof rockcharacter of gateway at the 12501 th mining faceschanges with the change of location,which dominated by quartz sandstone, high strength, containing coal particles in former 400 m. Roof in shallow is Sandy mudstone and Siltstoneinterbedded structure, joint development, fractured obvious, lowstrength. Roadway roof is dominated by mudstone and sandstone between the 400m~700m.and final section of roadway roof has a large number of carbonaceous mudstone.?Roof rock of gateway at the 12501 th mining facesis mainly black carbonaceous mudstonewith felling dregs in punching process, helix. More than half part of roof rock is for high strength, integrity, good sand, which has a significant impact on roof stability after drilling? Main haulage roadway in roof is mainly weaker mudstones,joint development.sandstone of the upper has high intensity and good integrity,which plays a decisive roleon roof stability.The rock strata by the influence degree of the water are not the same and there are large differences in the softening coefficient. The softening coefficient of medium sandstone is maximum and the maximum value is 1.22; the softening coefficient of carbon mudstone is minimum and the minimum value is 0.18.(3) The petrological characteristics of coal-bearing formation of Tunlan Coal MineThis paper have forecasted the positation of stable rock in the south area of Tunlan coal mine by using IDW with angle weighted repaired. This paper also have got the the classification results and the calculation of partition line in different levels hidden partition according to the forecast results. The classification results show that:? The Tunlan Coal Mine sedimentary rock compositional maturity is low and shows that the sediments without long distance transportation, which can be inferred in Tunlan Coal Mine should be located in the middle and lower region of the river;The compositional maturity of Tunlan Mine is lower, the cement is dominated by clay, the content of stabilizing component is relatively less, and the content of clay is high, the depositional environment for coal-forming environment floodplain river depositional systems.3. Research of roadway roof stability classificationBased on the Tunlan mine existing geological drilling, geological formations situation and Tuen mine's status quo, combined with the research of core drilling experiment and rock physical and mechanical properties test results, the roof stability of Tunlan mine in southern is classificated, Roof stability classification area as shown in figure 7.1. By the classification results can be obtained:(1) In the figure of the area of roof stability classification, roof stability classification has larger difference, mainly in class ? roof(unstable roof), accounting for more than 60%~ 70%of the classification area. This area exists more fault structure, and the roof stability is poor. The risk of roof fall is higher and the roof surrounding rock is relative broken in this area, so it should try to improve the support strength and support density of the bolt(anchor cable).(2) Followed by class?roof and class ? roof, accounting for about 10% of the area of roof classification, mainly distributed in the north and south of the classification area. And the area of class?roof and class ? roof cross each other, no obvious rule; The roof of these area is relatively stable, so bolt support of class?roof can be used separately and the class ? roof should be appropriate with the length of anchor cable above 4m to support.(3) Class IV roof or unstable roof, mainly distributed in the centre of the classification area, accounting for about 20%~ 30%of classification area. This area exists more fault structure and fault throw is bigger, and this seriously influences the roof stability of roadway. The risk of roof fall of Class IV roof is higher, so it should try to improve the support strength and support density, and it should strengthen the regional underground pressure monitoring, timely supplement support.4 Designing and analysis of the roadway control scheme(1) Combined with the Tunlan mine specific conditions, Evaluated the adaptability of the existing support design methods, and ultimately determined to use the theoretical calculation method that based on the classification of roadway roof stability to design the bolt(Cable) support parameters of the roadway.(2) The law of instability of the roof of roadway of two schemes: in the process of roadway roof subsidence, shoulder of roadway preferred failure, at the same time a bit there roof separation, then there is roof instability, use bolt and anchor combined support scheme, the gateway roof separation is in the point that 3m from the roof, with no anchor supporting scheme,it is about 4.9m.(3) In numerical simulation experiment, compared with bolt and anchor combined support scheme, the range full-length rock bolt scheme, is higher safety.5 Underground pressure monitoringCarrying underground pressure monitor on spot field which has been adopted supporting plan,it includes the deep basic point monitoring and surface monitoring,the interaction result of supporting and wall rocks are visually reflected, after 30 days' observation,by carrying statistical analyzing on roof of different caving potential safety hazard level,we can have the conclusion:though in different caving potential area,it can keep steady by adopting necessary measures,the ? and ? kinds of roof have high caving potential,but the deformation is still controllable.In the whole observation period,the roof's whole stability is relatively good, no small parts have caving.After using new supporting pattern,deformation of tunnel roof is relatively small,at the same time,it can keep steady by just a short time,effects of the supporting pattern can satisfy the project demanding.The observation results show that,supporting pattern which is designed based on caving safety levels can satisfy the spot field's demand,resolving the hard supporting problem of Tun Lan Tunnel,it has important theoretical significance and large economic benefit. |
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