【作者】 杨德传；

【导师】 高明中；

【作者基本信息】 安徽理工大学 ， 采矿工程， 2013， 博士

【摘要】 目前,我国矿井每年以10-25m的速度向深部延深,深部开采面临“三高一扰动”,即高应力、高地温和高岩溶水压及强烈的开采扰动影响,严重制约煤矿的安全高效开采。深部围岩地质条件复杂多变,其中,在围岩控制方面,以厚层复合顶板岩层的控制难度很大,厚层复合顶板在留巷过程中,会产生严重的离层,加上充填体的剧烈变形,极易诱发顶板事故,这和深部开采面临的突水、煤与瓦斯突出构成深部开采的主要工程灾害。为了实现深部煤炭的安全高效开采和生产的快速接替,解决深部煤层高瓦斯对生产的制约影响,在卸压抽采采动裂隙瓦斯,采用上向和下向钻孔抽采邻近煤层裂隙瓦斯和实行Y型通风的基础上,利用采动形成的支承压力在采空区边缘的低应力区,进行无煤柱沿空留巷,既解决深部上隅角的瓦斯超限难题,又为留巷围岩的稳定提供了可利用的有利条件。深部厚层复合顶板条件下的沿空留巷,在工作面开采引起留巷上覆岩层的变形-断裂和下沉运动,在工作面倾向和竖直方向上形成“横三区,竖三带”,即倾向方向上留巷采空区边缘的低应力区、煤帮应力增高区、原岩应力区及竖直方向向上依次为垮落带、裂隙带和弯曲下沉带；由留巷上覆岩层运动形成的“内、外”应力拱的动态演化,留巷上覆岩层“外”应力拱拱内破断岩层形成留巷围岩的“大”结构,当工作面推进到采面长度左右时,覆岩“外”应力拱的拱高扩展高度达到最大,随着工作面的继续推进,应力拱的扩展高度基本不变,“大”应力拱的拱脚随工作面的推进有向深部移近的趋势；“内”应力拱形成留巷围岩的“小”结构,“内”应力拱拱脚向深部移近较“外”应力拱更为缓慢,“大”结构的破断运动促使“小”结构受到很大冲击作用并产生剧烈变形运动,这种变形是否能够达到耦合,与留巷围岩的支护结构、支护参数和支护的时空关系等密切相关。深部煤层顶板大多表现为复合顶板,薄层复合顶板下留巷时顶板较易控制,而厚层复合顶板下留巷围岩呈现全断面来压,其留巷围岩变形程度明显地强烈于浅部和中硬顶板,围岩变形具有显著的分区裂化现象,留巷围岩变形具有明显的不均衡性和持续流变特性,其破坏形式主要有挠曲、剪切、拉伸及压缩破坏形式,厚层复合顶板的塑性离层明显、层间弯曲和因错动而产生的层间离层,使得留巷顶底板产生明显的增垮效应,普通锚杆与锚索难以将厚层复合岩层锚固在深部坚硬岩层中,难以形成留巷围岩稳定的拱结构,在外层“大”结构的冲击作用下,留巷围岩“小”结构极易产生失稳。深部厚层复合顶板岩层大致可分为全软岩层、上软下硬岩层和上硬下软复合岩层三种,在不同类型复合顶板条件下进行留巷的难易程度也明显不同,通过正交数值分析可知全软型厚层复合顶板离层下沉量最大,上硬下软厚层复合顶板次之,上软下硬厚层复合顶板离层下沉量最小。本文主要运用岩层控制关键层理论和弹塑性理论,构建深部留巷基本顶和厚层复合顶板运动的力学模型,对留巷基本顶关键块的运动规律和复合直接顶变形规律进行力学分析,得出复合顶板的挠曲变形方程,并分析其底鼓变形的力学机理。通过FLAC3D分析厚层复合顶板下留巷覆岩“内、外”应力拱的演化特征围岩的应力场和位移场的演化规律；通过正交分析揭示了厚层复合顶板类型、充填体宽度、充填体强度、煤体强度、巷内不同支护形式和采空区压实刚度对厚层复合顶板留巷围岩应力与变形的影响强弱关系,通过实验室相似模拟分析厚层复合顶板沿空留巷围岩随采动影响下的变化规律,为深部厚层复合顶板下留巷围岩的控制提供了思路。最后,针对深部厚层复合顶板沿空留巷围岩变形的时空特征,提出了非均衡控制和底板锚注支护控制技术,对关键部位分段分区加固支护,对厚层复合顶板进行锚杆加长短锚索进行梯次立体锚固支护,在留巷巷内复合顶板岩层中形成一定厚度和承载强度的具有组合锚固效应的阶梯式立体支护结构,能有效控制厚层复合顶板的过度离层变形,同时加强留巷煤帮支护强度,确保合理的充填宽度和充填体强度,减弱厚层复合顶底板增跨效应带来的不利影响,防止厚层复合顶板产生变形失稳。对底板及两角部位进行锚注支护,可以有效控制留巷底鼓,有利于深部厚层复合顶板留巷围岩“小”结构的相对稳定。更多还原

【Abstract】 At present, with the coal mining propelling to the deeper levels underground at the rate of20-30m each year, our coal mines face "three high situations and one disturbance", namely, high stress, high ground temperature, highland mild high karst water pressure and strong mining disturbance. The status seriously restricts the safe and efficient mining in depth. The geological condition of the surrounding rock is complicated. In the control over the surrounding rock, the thick layer composite roof strata is difficult to control. The thick-layer composite roof in the course of gob side entry retaining is subject to severe bed separation, which together with the severe deformation of the filling body, can lead to roof accident. This accident, like the water inrush, coal and gas outburst, is regarded as the main engineering disasters in the deep coal mining.In order to achieve safe and efficient mining and rapid succession in the deep coal mines, and solve gas restriction on coal mining, An approach is to release pressure and drain the gas in the fracture of the coal seam. Specifically speaking, on the premise of conducting uphole and downhole drilling to extract the fracture gas in the adjacent coal seam and adopting y-shaped ventilation, I carry out no-coal-pillar gob-side entry retaining at the edge of low-stress area of the goaf. Such way can both solve the gas overrun problem in upper corner of the working face, and offer favorable conditions for the stability of the surrounding rock of the gob-side entry retaining.The characteristics of the gob-side entry retaining under the condition of thick-layer composite roof in deep coal mine is as follows. In the process of working face advancing, the coal mining causes the strata to be deformed and fractured, and induces "three areas along horizontal direction and three zones on vertical direction", namely, the low-stress area at the edge of goaf of gob-side entry retaining, increasing-stress area and the original rock stress area in the coal body of gob-side entry retaining, and the caving zone, fractured zone and bend submerged zone in turn on the vertical direction. The overburden strata movement of gob-side entry retaining forms the dynamic evolution of the "internal and external" stress arch. The numerical analysis of FLAC3D is applied to analyze the "large" structure of the surrounding rock in the gob-side entry retaining formed by the fractured stratum within the "external" stress arch in the overburden strata. When the working face advances to the working face length orso, the stress arch of overburden strata expands to the highest; with the working face pushing forward, the expansion height of the stress arch basically remains unchanged, and the arch foot of" big "stress arch transfers to the deep coal body of gob-side entry retaining. Surrounding rock of gob-side entry retaining under thick composite roofs lies in the "small" structure formed by the movement of overburden rock. The arch feet of inner stress arch transfer to the depth of coal body more slowly than outer stress arch. The fracture of the "big" structure induces great deformation of the "small" structure. Whether the deformation is coupled or not is directly related to the supporting structure, parameter and time-space relationship of the surrounding rock of gob side entry retaining.The roof of coal seam is mostly composite roof in deep coal mines, and thin-layer composite roof is more easily to be controlled. The surrounding rock of gob side entry retaining under thick-layer composite roof appears to be whole roadway-section pressure, and the degree of deformation of the surrounding rock of gob-side entry retaining is obviously stronger than that in shallow coal mines, and in addition, the deformation takes on prominent subarea cracking, obvious imbalance and continuous rheological behavior. Its main forms of damage are flexure, shear, tensile and compression. The thick layer of composite roof of gob-side entry retaining has plastic abscission layer, interlayer bending and interlayer abscission layer caused by composite rocks dip offset. The roof and floor is found to have obvious increasing span effect. The ordinary bolt and anchor cable can hardly anchor thick-layer composite rock in deep hard-roof rock, which makes it difficult for the surrounding rock of gob-side entry retaining to form the stable arch structure, and the instability is highly probable under the dynamical impact of "big" structure.The strata of thick-layer con posite roof can be roughly divided into three kinds, such as the entirely soft rocks, the upper soft and lower hard stratum, and the upper hard and lower soft stratum. For different types of composite roof, the difficulty of the surrounding rock of gob-side entry retaining varies. The subsidence of the abscission layer is different. Through the orthogonal numerical analysis, the composite roof with entirely soft rock is proved to reach the maximum, the upper hard and lower soft stratum takes second place, the upper soft and lower hard stratum is the least.This paper applies the critical layer theory of strata control and elastic-plastic theory to build mechanical models of the movement of main roof and thick-layer composite roofs, and to analyze the motion of the key block of main roof and the deformation of the composite immediate roof. It concludes the deflection formula of composite roof, and analyzes the mechanics mechanism of deformation of floor heave. FLAC3D is used to analyze evolution characteristics of "inside and outside" stress arch of overburden rock, the stress of surrounding rock and the evolution of displacement fields. The orthogonal analysis reveals that the different types of composite roof, the width and strength of filling body, the strength of coal body, different supports in gob-side entry retaining and the compaction stiffness goaf have an effect on the stress and deformation of the surrounding rock under thick-layer composite roof, and laboratory analog simulation analysis shows the stress and deformation of the surrounding rock under thick composite roof, which provides a train of thought on controlling the deformation of surrounding rock of gob-side entry retaining.The paper, finally, according to the temporal and spatial characteristics of the deformation of surrounding rock of gob-side entry retaining of thick-layer composite roof proposes the non-symmetry control and boltgrouting control technology. Sub-partition reinforcement is completed on the key position in the course of gob-side entry retaining, and multistep stereoscopic anchoring supporting is completed on thick-layer composite roof, and forms multistep supporting structure with a certain thickness and bearing strength in roadway of gob-side entry retaining under thick-layer composite roof. the technology can effectively control the separation and deformation of thick-layer composite roof, and in the mean time strengthen the support of lane-side coal body, ensure the proper strength and width of the filling body, reduce the composite roof increasing span brings adverse effects, and help to prevent deformation instability of thick-layer composite roof. The application of bolt-grouting support in the bottom floor and the two horns of gob-side entry retaining can effectively control floor heave of gob-side entry retaining, and avail to the stability of "small" structure of surrounding rock of gob-side entry retaining under thick-layer composite roof in deep coal mine.更多还原