无煤柱分阶段沿空留巷煤与瓦斯共采方法与应用

针对深井高瓦斯低透气性煤层群的典型赋存特征,结合淮南矿区千米深井无煤柱煤与瓦斯工程实践,提出了改进Y型通风模式,即分阶段沿空留巷方法,完善了对共采工程的维控预应力锚固技术.工程实践表明:预应力锚固技术可以实现深井强动压开采过程中对沿空留巷和回风巷道围岩稳定的有效维控,至第1阶段结束,留巷顶板下沉量为144mm,两帮移近量为351mm,分阶段沿空留巷对共采巷道的维护时间缩短了4/5.减少了留巷变形速度稳定后累计变形的不利影响.超前工作面布置的瓦斯抽采工程中,单孔抽采瓦斯浓度(体积分数)达到40%,实现了煤与瓦斯共采.     

深部沿空切顶成巷围岩稳定性控制对策

基于沿空切顶成巷技术原理,以城郊煤矿深部工作面无煤柱开采为背景,综合运用力学分析﹑模拟计算和现场试验等方法,对深部切顶成巷围岩控制关键对策进行深入研究。结果显示：切顶留巷顶板在侧向形成短臂梁结构,降低了巷旁支护体所受压力,切缝范围内岩层垮落后碎胀充填采空区,使留巷顶板下沉量降低了约50%。采空区侧顶板为切顶巷道围岩变形的关键部位,需进行加强支护;深部切顶巷道实体煤帮塑性区范围大,通过煤帮锚索支护技术可将浅部锚杆承载层锚固在弹性区稳定煤体中;深部切顶成巷来压速度快、强度大,巷内单体支柱易造成冲击破断,采用高阻力液压支架巷内临时支护时可较好地抵抗深部强动压;巷旁刚性挡矸装置因无法适应深部围岩大变形而受压弯曲破坏,深部切顶巷道巷旁挡矸结构需实现一定的竖向让位卸压方可与顶底板协调变形。在研究的基础上提出恒阻锚索关键部位支护+可缩性U型钢柔性让位挡矸+巷内液压支架临时支护+实体煤帮锚索补强的深部切顶成巷联合支护技术,并进行现场工业性试验。现场监测结果表明：留巷围岩在滞后工作面约290 m时基本稳定,且稳定后各项指标满足下一工作面使用要求。     

Spontaneous caving and gob-side entry retaining of thin seam with large inclined angle

Based on the research method of combining simulation analysis with field testing by distinct element process UDEC, we have analyzed the roof deformation and failure laws and roadway support technology of gob-side entry retaining in a thin seam with a large inclined angle. The results show that during exploitation in seams with large inclined angle, rotational subsidence of the main roof under the gob area is small and can maintain balance, so there is no need to provide artificial permanent support resistance for the main roof near the upper side to control rotational subsidence. Obstructed by the dense scrap rail, waste rock from the immediate roof caving slides from the upper gob area to the lower area and fills it, which strikes a balance between the immediate roof under the goaf after it fractures into large pieces and filling waste rocks.     

薄煤层开采工作面电磁辐射特征

采用电磁辐射技术及装备对薄煤层开采工作面进行电磁辐射监测,深入分析了薄煤层开采工作面电磁辐射显现特征.研究结果表明:采用沿空留巷巷道布置方式,受上区段采空区影响,工作面上巷电磁辐射强度及波动性都高于下巷;工作面来压前电磁辐射增强,来压后减弱,回采过程中电磁辐射呈现明显周期性;薄煤层冲击地压发生于电磁辐射短时间升高的峰后阶段,区别于厚煤层发生于电磁辐射增大到较高值一段时间,然后下降至低值并持续一段时间后.应用电磁辐射对薄煤层开采工作面进行应力分析及冲击地压预测时应充分考虑其特点,以提高分析预测准确性.     

突出矿井深部新水平开采瓦斯综合治理模式研究

针对矿井浅部瓦斯治理模式已不能保障深部采区安全高效生产的现状,提出一种适宜矿井深部新水平开采的瓦斯综合治理模式.工作面消突采用底板岩巷穿层钻孔预抽煤巷条带瓦斯;底板岩巷布置“一巷多用”,在工作面回采工程中可兼做回风巷、尾抽巷、措施巷;回采工作面采用沿空留巷Y型通风综合治理瓦斯.其中,顺层钻孔预抽本煤层瓦斯,高位钻场顶板走向钻孔抽采裂隙带瓦斯,上隅角、尾巷埋管抽采采空区瓦斯,形成矿井三维立体瓦斯抽采体系.     

Control mechanism and technique of floor heave with reinforcing solid coal side and floor corner in gob-side coal entry retaining

Floor heave is the most common convergence in gob-side entry retaining. The paper analyzes the form, process and characteristics of gob-side entry retaining with the comprehensive methods of theoretical analysis, numerical simulation and the field trial. Research results present that bending and folding floor heave is the main factor in the stage of the first panel mining; squeezing and fluidity floor heave plays a great role in the stable stage of gob-side entry retaining; the combination of the former two factors affects mainly the stage of the second mining ahead; abutment pressure is a fundamental contribution to the serious floor heave of gob-side entry retaining, and sides corners of solid coal body are key part in the case of floor heave controlling of gob-side entry retaining. Floor heave of gob-side entry retaining can be significantly controlled by reinforcing sides and corners of solid coal body, and influence rules on the floor heave of gob side entry retaining of sides supporting strength and the bottom bolt orientation in solid coal side are obtained. Research results have been successfully applied in gob-side entry retaining of G20-F23070 face haulage roadway in #2 coal mine of Pingmei Group, and the field observation shows that the proposed technique is an effective way in controlling the floor heave of gob-side entry retaining.     

Stability control of gob-side entry retained under the gob with close distance coal seams

In multi-seam mining, the interlayer rock strata between the upper coal seam(UCS) and the lower coal seam(LCS) appear damage and strength weakening after mining the UCS. Ground stability control of the gob-side entry retaining(GER) under the gob with close distance coal seams(CDCS) is faced with difficulties due to little attention to GER under this condition. This paper focuses on surrounding rock stability control and technical parameters design for GER under the gob with CDCS. The floor rock strata damage characteristics after mining the UCS is first evaluated and the damage factor of the interlayer rock strata below the UCS is also determined. Then, a structural mechanics model of GER surrounding rock is set up to obtain the main design parameters of the side-roadway backfill body(SBB) including the maximum and minimum SBB width calculation formula. The optimal SBB width and the water-to-cement ratio of high water quick-setting material(HWQM) to construct the SBB are determined as 1.2 m and 1.5:1.0,respectively. Finally, engineering trial tests of GER are successfully carried out at #5210 track transportation roadway of Xingwu Colliery. Research results can guide GER design under similar mining and geological conditions.     

Stability study on naturally filling body in gob-side entry retaining

In the construction of the filling gob-side entry retaining in a lane, we utilize the self-slide natural phenomenon of a falling gangue in an inclined coal seam goaf. First, we put the falling gangue of goaf above the laneway and made it the main filling material by adopting the measurement of flexible supporting system combined with those of rigid supporting system. Then we made the filling material gunited and solidified to maintain the filling goal of the gob-side entry retaining beside the lane. Considering the law of energy conservation and law of pressure distribution for retaining the active and static soil of the wall, we analyzed the reliability of a gangue blocking facilities and the stability of the filling material in the lane. We analyze the figures to see the stability. The result shows that the gangue block supporting system is reliable, and has been successfully practically applied.     

近距离煤层群首采保护层工作面瓦斯综合治理技术研究

瓦斯治理仍是世界性难题。本文针对赤峪煤矿近距离高瓦斯煤层群首采保护层C0202工作面瓦斯治理问题,提出了沿空留巷Y型通风配合本煤层顺层钻孔、两巷底板穿层钻孔、顶抽巷高位穿层钻孔、采空区埋管的＂五措并举＂治理措施,实现了工作面成功连续留巷200m,瓦斯抽采率高达70%,回风流瓦斯浓度控制在0.4%左右的效果,保证了工作面的安全高效开采。该研究成果可为赋存条件相似的煤层群开采瓦斯治理提供借鉴。     

Comparative study of model tests on automatically formed roadway and gob-side entry driving in deep coal mines

Automatically formed roadway(AFR) by roof cutting with bolt grouting(RCBG) is a new deep coal mining technology. By using this technology, the broken roadway roof is strengthened, and roof cutting is applied to cut off stress transfer between the roadway and gob to ensure the collapse of the overlying strata. The roadway is automatically formed owing to the broken expansion characteristics of the collapsed strata and mining pressure. Taking the Suncun Coal Mine as the engineering background, the control effect of this new technology on roadways was studied. To compare the law of stress evolution and the surrounding rock control mechanisms between AFR and traditional gob-side entry driving, a comparative study of geomechanical model tests on the above methods was carried out. The results showed that the new technology of AFR by RCBG effectively reduced the stress concentration of the roadway compared with gob-side entry driving. The side abutment pressure peak of the solid coal side was reduced by 24.3%, which showed an obvious pressure-releasing effect. Moreover, the position of the side abutment pressure peak was far from the solid coal side, making it more beneficial for roadway stability. The deformation of AFR surrounding rock was also smaller than the deformation of the gob-side entry driving by the overload test. The former was more beneficial for roadway stability than the latter under higher stress conditions. Field application tests showed that the new technology can effectively control roadway deformation. Moreover, the technology reduced roadway excavation and avoided resource waste caused by reserved coal pillars.     

Analysis and application in controlling surrounding rock of support reinforced roadway in gob-side entry with fully mechanized mining

In order to optimize gob-side entry in fully-mechanized working face in moderate-thick-coal seams,we adopt a new attempt to pack roadside by pumping ordinary concrete,which is very important for the development of gob-side entry technology.The concrete has a long initial setting time and a low initial strength.So it is difficult to control the surrounding rock.In this paper,we analyze the effect of using roadside cable to reinforce supporting in gob-side entry surrounding rock controlling based on elastic-plastic and material mechanics knowledge.And then we propose a scheme that cable is used to reinforce roadside supporting and a single hydraulic prop is used as the temporary supporting in gob side.Using the numerical simulation software FLAC2D,we numerically simulated supporting scheme.Results of both the 2D modeling and the industrial test on No.3117 face in Jingang Mine prove that the scheme is feasible.The results show that the technology of protecting the roadway in gob-entry retained efficiently make up the deficiency of roadside packing with ordinary concrete,effectively control the roof strata and acquire a good result of retaining roadway.     

急倾斜煤层开采诱发地表裂缝数值模拟

为了研究急倾斜煤层开采诱发地表裂缝的演化过程,探讨急倾斜煤层开采诱发地裂缝分布规律.利用可描述拉张破裂的有限元方法,对地表裂缝演化过程进行数值模拟.结果显示:最大拉应力集中在地表,地表优先于采空区破裂,采空区下山方向对应的地表一侧形成裂缝.急倾斜煤层开采地表和采空破裂的顺序与水平、倾斜煤层的破坏顺序相反.煤层倾角很陡时,地表先破裂到一定程度后,采空区才开始破裂.煤层倾角很缓或水平时,采空区先破裂,之后地表才破裂.     

Surrounding rock control of gob-side entry driving with narrow coal pillar and roadway side sealing technology in Yangliu Coal Mine

Gob-side entry driving can increase coal recovery ratio, and it is implied in many coal mines. Based on geological condition of 10416 working face tailentry in Yangliu Coal Mine, the surrounding rock deformation characteristics of gob-side entry driving with narrow coal pillar is analysed, reasonable size of coal pillar and reasonable roadway excavation time after mining are achieved. Surrounding rock control technology and effective roadway side sealing technology are proposed and are taken into field practice. The results showed that a safer and more efficient mining of working face can be achieved. In addition, results of this paper also have important theoretical significance and valuable reference for surrounding rock control technology of gob-side entry driving with narrow coal pillar under special geological condition.     

Rock burst mechanism analysis in an advanced segment of gob-side entry under different dip angles of the seam and prevention technology

In order to investigate the frequent occurrences of rock burst in gob-side entry during the mining process of the mining zone No. 7, the mechanical model of main roof of fully-mechanized caving mining before breaking was established by the Winkler foundation beam theory, and the stress evolution law of surrounding rock with different dip angles of the seam during the mining process was analyzed by using FLAC3 D. The results show that: with the dip angle changing from 45° to 0°, the solid-coal side of gobside entry begins to form an L-shaped stress concentration zone at a dip angle of 30°, and the stress concentration degree goes to higher and higher levels. However, the stress concentration degree of the coalpillar side goes to lower and lower levels; the influence range and peak stress of the abutment at the lateral strata of adjacent gob increase with dip angle decreasing and reach a maximum value at a dip angle of 0°, but the tailgate is not affected; the abutment pressure superposition of two adjacent gobs leads to stress concentration further enhancing in both sides of gob-side entry. With the influence of strong mining disturbance, rock burst is easily induced by dynamic and static combined load in the advanced segment of gob-side entry. To achieve stability control similar to that in the roadway, the key control strategy is to reinforce surrounding rock and unload both sides. Accordingly, the large-diameter drilling and high-pressure water injection combined unloading and reinforced support cooperative control technology was proposed and applied in field test. The results of Electromagnetic Emission(EME) and field observation showed that unloading and surrounding rock control effect was obvious.     

Stability of coal pillar in gob-side entry driving under unstable overlying strata and its coupling support control technique

Considering the situation that it is difficult to control the stability of narrow coal pillar in gob-side entry driving under unstable overlying strata, the finite difference numerical simulation method was adopted to analyze the inner stress distribution and its evolution regularity, as well as the deformation characteristics of narrow coal pillar in gob-side entry driving, in the whole process from entry driving of last working face to the present working face mining. A new method of narrow coal pillar control based on the triune coupling support technique (TCST), which includes that high-strength prestressed thread steel bolt is used to strain the coal on the goaf side, and that short bolt to control the integrity of global displacement zone in coal pillar on the entry side, and that long grouting cable to fix anchor point to constrain the bed separation between global displacement zone and fixed zone, is thereby generated and applied to the field production. The result indicates that after entry excavating along the gob under unstable overlying strata, the supporting structure left on the gob side of narrow coal pillar is basically invalid to maintain the coal-pillar stability, and the large deformation of the pillar on the gob side is evident. Except for the significant dynamic pressure appearing in the coal mining of last working face and overlying strata stabilizing process, the stress variation inside the coal pillar in other stages are rather steady, however, the stress expansion is obvious and the coal pillar continues to deform. Once the gob-side entry driving is completed, a global displacement zone on the entry side appears in the shallow part of the pillar, whereas, a relatively steady fixed zone staying almost still in gob-side entry driving and present working face mining is found in the deep part of the pillar. The application of TCST can not only avoid the failure of pillar supporting structure, but exert the supporting capacity of the bolting structure left in the pillar of last sublevel entry, thus to jointly maintain the stability of coal pillar.     

综放沿空留巷围岩变形影响因素的分析

从技术因素和地质因素两个方面重点论述了综放巷内充填沿空留巷围岩变形和应力分布的基本特征．通过计算机数值模拟，优化了充填工艺参数，得出了合理的留巷技术方案．在此基础上，系统分析了煤层硬度、采高、直接顶厚度和硬度、老顶岩层硬度及关键层复合效应等因素对留巷围岩变形与垂直应力分布的影响规律．并采用多元分析方法，得到了各因素对围岩最大应力的回归方程．研究结果可对综放巷内充填沿空留巷的应用提供理论依据和设计指导．     

放顶煤开采沿空留巷围岩移动规律及变形特征

运用适于分析岩层断裂和垮落的数值模拟软件UDEC建立了相应的模型，分析了综放沿空留巷围岩应力和位移的演变过程、围岩移动的特征，阐述了巷道和充填体上方顶煤的位移及其与上覆岩层破断之间的关系，为沿空留巷充填体参数选择提供科学依据．     

厚煤层全煤巷采区巷道布置关键技术研究

在分析煤矿开采过程中大量矸石排放造成矿区土地资源浪费、水资源破坏和大气污染现状的基础上，根据采煤技术发展现状，提出了厚煤层采区全煤巷布置系统，并对厚煤层采区煤层上山(或煤层大巷)的维护、采空区排水和防灭火等关键技术进行了研究，以实现厚煤层矿井的安全、高效、洁净开采。     

薄煤层开采对上覆构筑物基础变形影响的数值模拟研究

煤层开采过程中,在煤层顶、底板岩层一定的条件下,煤层的倾角和埋深对地表变形有很大的影响。通过三维有限元数值模拟,研究平缓或缓倾斜煤层、倾斜煤层、急倾斜煤层开采对上覆构筑物基础变形的影响,依据特定构筑物对倾斜变形、水平变形和基础沉降最大值的容许要求,提出安全煤柱（移动角γ、β）的保护范围,为构筑物安全运行和煤矿合理开采提供依据。     

Layout and support technology of entry for pillar face

In order to improve the recovery rate of coal, some mines have begun to recover the residual protective pillars in the form of short wall faces. However, it is difficult to control stability of the haulage entry and the ventilating entry under the mining influences of the pillar face and the two side faces. Thus the 4311 face, which was designed to recover the 57 m wide residual protective pillar in Guojiashan Coal Mine,was taken as engineering background. Distribution law of stress and plastic zone in the residual protective pillar was analyzed using the numerical simulation. Then the gob-side entry driving technology was proposed to layout the entries for the pillar face. Based on the analysis of stress distribution and deformation characteristics of surrounding rocks in gob-side entry driving with different width of narrow pillars, the width of the narrow pillar of the entries in the 4311 face was decided to be 4 m. In order to control stability of the gob-side entry driving, the mechanical model of the main roof was established and deformation characteristic of surrounding rock was analyzed. Then the bolt support technology with high strength and high pre-tightening force was proposed for entry support. Especially, the hydraulic expansion bolts were used to support the narrow pillar rib. The engineering results show that the width of the narrow pillar is reasonable and the entry support technology is effective. The research achievement can provide some references to pillar recovery for other coal mines.