| High intensity of mining status has been existed in China for many years, wheremore and more collieries trying to enter deeper and with the downward speed more than8~10m/a. Certain amount of inclined coal seam exist among them, where theexcavation shows a series of distinctive deformation characteristics like durativeasynchronism and spatial asymmetry. It is obvious that the consequential hiddendangers, like supporting failure or structural instability, will bottleneck the highrecovery of inclined coal seam.Combined measures of engineering research, theoretical analysis, physicalsimulation and numerical calculation are applied in this dissertation and thussuccessfully summarize the deformation and breakage characteristics of different areasof roadway, including roof, floor, sides and corners, there also further analyzes the stressdistribution law of these areas and illuminates the mechanism of unsymmetricaldeformation in different areas, then prosperously reveal the space-time evolution lawof the unsymmetrical deformation in different areas, finally the corresponding stablecontrolling technology for unsymmetrical deformation of roadway buried in inclinedstrata is proposed and also been verified in field application, the main conclusions areshown as follows,(1) Entry’s deformation of inclined deep strata is featured by distinctive timesequence，the general breakage sequence is: Roof, area that tangent to the layer of strata,floor, base angle of higher side and then lower side, and the last one is shoulder ofhigher side. The mechanical analysis manifests that unsymmetrical deformation willshow out sooner as the smaller angle that between the shear stress direction and strata’sinclination.(2) We manufactured Dthree-dimensional and five face vertical primaryload testsystem which is configured by neotype modular design, compute integrated controlling,and automatic strain/stress gathering model, it thus can realize independent load (threedirections and five faces) on the test block, the active load stress of each face can reach20MPa, then ideal different three-dimensional stress state can come true according tothe design requirements. The maximum size of the test block is1000×1000×400mm.(3) Unsymmetrical deformation speciality of deep inclined strata was revealedbased on the three-dimensional physical experiments. There set up two simulatedinclination, namely,30°and45°, results indicated that though deformation of higher rib side was small, interior joints were greatly developed and horizontal joints run throughalong the entry’s axial direction. Deformation of lower rib side was relative large butthe interior horizontal joints were rare. Considering the deformation of entry’s roof,shoulder of higher rib side was relative smaller than the lower rib side. But it showncomplete contrary as to entry’s floor, base angle of higher rib side was relative largerthan lower rib side. This phenomenon tends to be much more dramatic in sides as theinclination increases, however, it tends to mitigate as to floor.(4) Numerical simulation also testified the unsymmetrical deformation ofsurrounding rock, computational software3DEC was adopted here and fourteeninclinations varied from10°to90°had been initiated. The simulated resultsdemonstrated that unsymmetrical deformation decreased versus the increase ofinclinations and it would head for alleviation as the inclination surpasses45°.Horizontal displacement of sides would increase with the inclination’s increasing whilethe vertical shown contrary variation. The peak value of roof’s displacement located atthe both sides of the tangency point between the strata and entry, which also wouldtransfer to the lower rib side as the inclination increases and simultaneously roof’shorizontal displacement increased gradually while vertical displacement decreasedgradually. Under the circumstance that the inclination of strata is less than15°or morethan80°, the contour lines of maximum main stress shown circular distribution and thestress distribution was little influenced by the inclination, when beyond theaforementioned range, however, if build a coordinate system by strata inclination andnormal firstly, then there had relative large main stress located at the quadrant bisector,the stress was close to the surface of roadway, and the contour lines of maximum mainstress shown clover distribution and whose distribution center coincided with theentry’s center.(5) Influence on unsymmetrical deformation which applied by stress state ofsurrounding rock was analyzed when the inclination was30°. Displacement contourlines was symmetrical along the normal line which went through the tangency pointbetween strata and entry under the condition that the side pressure coefficient equaledto1, in addition, the slippage and separation of strata also shown approximate symmetry.The displacement of surrounding rock was concentrate in entry’s sides and slippagearea in the roof and floor if side pressure coefficient surpassed1, if the side pressurecoefficient was less than1, however, the other way around. It was thus obvious that allof displacement value, displacement range, slippage value and slippage range were directly proportional to rock’s stress, the former ones shown distinctive variation aslatter seriously changed.(6) This dissertation also initiated the new technical thoughts of Dstressoptimization-property improvement-structure strengthen, which systematicallyinnovated the reinforcement on unsymmetrical deformation, there also put forward thetheory of priority reinforcement, as what it called, it focused on the priorityreinforcement on the areas where the early formed unsymmetrical deformation located,thus to avoid the continuous deformation and structural instability under the high stressin inclined strata.(7) This dissertation also came up with the technique of step-by-step anchoringmethod to improve mechanical property of surrounding rock, whose kernel was thecombination of grouting and deep hole cable grouting, based on priority reinforcement,regional structural strengthen technique, Dthree highs anchoring technology, andprestressed cable truss structure, vulnerable region can be efficiently supported, and thestrength of supporting structure also can be improved by interior-exterior bearedcoupling system and backfill grouting technology(8) Different engineering practices that concerned inclined strata verifiedaforementioned theoretical results, they were-850m eastern rocky roadway of QujiangMine,601numbered half-coal roadway of Qujiang Mine, and gob-side side entryretaining with little coal pillar retained of Xieqiao Mine, Huainan Mining Group. |
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