Study On Roadway Supporting Structure And Stability Coupling Control Of Surrounding Rock Of Extra-thick Compound Roof

Extra-thick compound roof is unstable layered strata. It is difficult to interpret anchor mechanism and roadway support structure in traditional support theory, even more difficult to reasonably determine the parameters of the support. On the basis of summing up the theory and technology of the existing roadway support, combined with the project of National Foundation of China (51274145) named "covers peak after large deformation process of surrounding rock and support balance of law and control mechanism" and gasification project with special fund called "SHENZHOU Coal4#coal seam Combined Support Technology", this paper studies the extra-thick roof roadway support structure and rock stability control technology by using theoretical analysis, similar physical simulation, numerical simulation and practical application.The following are conclusions:(1) On the basis of summing up the existing support theory, this paper put forward a new theory of extra-thick roof roadway support, including:The damage of extra-thick roof mainly include bending fracture departure layer and ionospheric of layer shear dislocation; In the bolt role, low layered strata form a composite beam, extra-thick roof compression bearing arch formed in the role of anchor high prestressed,"arch" and "beam" coupling to form extra-thick roof roadway support structure; To establish roadway arch beam combination structural mechanics model proposed supporting structure stability mechanics checking analytic method.(2) The use of large-scale two-dimensional similar material simulation test system, taking the extra-thick roof of SHENZHOU Coal4#seam as a prototype, testing and simulating the displacement law of surrounding rock stress, change of surrounding rock under the different support conditions of roadway grading load (0～40MPa).The following are conclusions:①No support roadway:Displacement of the roof in shallow strata is μ=aln(p)+b logarithmic curve characteristics displacement in deep surrounding rock is μ=kp+b linear characteristic; the roof strata curved destruction from the middle to extend to both sides, with vaulted failure characteristics. Vertical stress with roof rock strata ionospheric destruction gradually leads both sides of the vertical stress increased the boost coefficient of1.12 to1.60; the rock horizontal stress increased gradually with the destruction of the rock formations of the upper strata level, boost coefficient of1.12to1.18; horizontal stress are the composite roof produce extrusion bending, shear dislocation destruction of the main reasons.②Bolting roadway:Displacement of the roof rock is μ=kp+b linear variation, displacement rate of anchor layer is greater than both sides, with characteristics of a combination beam bending deformation; when the bolt combined beam bending breaking up the rear, upper surrounding rock stress decreased strata destruction to both sides and the upper extension, and the last is still formed arch caving. The lateral pressure coefficient of anchor composite beam is1.45, indicating that the level of stress composite beam bending deformation; roof on both sides of the vertical stress is higher than the level of stress, indicating that the vertical stress is the main factors of the roadway shoulder shear failure.③Bolting and Anchor roadway:The bolt combined beam bending strength to be increased by the effect of anchor, stress of the upper surrounding rock of roof is rising, displacement of roof is decreasing. The displacement rate between the middle of the roof strata and both sides is descending from shallow to deep, indicating that the integrity of the surrounding rock of roof to be improved widely, with features of the anchor compression arch; the roof subsidence quantity has43%reduction.④Full-face support roadway:Under the diagonal anchor cable (compared with the vertical arrangement), the range of the surrounding rock compression arch is expanded, sinking declined by16%. The lateral pressure coefficient of roof bolt anchoring layer is increased to3.3, show that the horizontal stress is the main factor of combination of beam bending deformation. The bearing capacity of floor is increased and floor heave is decreased by employing bolts in the roadway floor.(3) By using of the RFPA numerical simulation test, taking extra-thick roof of SHENZHOU Coal4#seam as mock object, simulating the process stage loading in surrounding rock under the different support conditions. Computational analysis of the evolution of the characteristics of surrounding rock stress and rock crack. Respectively, studying the impact of different vertical stress and horizontal stress on the roadway stability law, and various supporting structure of the surrounding rock deformation damage were studied. Focus numerical computation on the structure features and supporting functions of anchor support roadway.(4) Combination of the above extra-thick roof roadway support theory and surrounding rock stability control technology, it is reasonable to optimize the design of roadway support parameters, and taking the practical application in the SHENZHOU Coal4303working face roadway and open-off cut. After monitoring, analysis and production application to verify the stability of the roadway support structure, and achieving a good supporting effect.