【作者】 杜晓丽；

【导师】 宋宏伟；

【作者基本信息】 中国矿业大学 ， 岩土工程， 2011， 博士

【摘要】 采动作用下的岩体应力转移变化所形成的压力拱演化规律研究,对于解决深部开采存在的软岩支护和冲击地压等问题具有重要的科学价值。利用数值模拟、相似物理模型、现场工程应用相结合的方法,研究了工作面推进过程中岩石压力拱的形成和演化规律;探讨了压力拱的影响因素;分析了采矿动压对附近巷道围岩稳定及冲击地压的影响;进而将压力拱的演化规律用于冲击地压的防治实践中,取得了如下的重要成果及创新点:(1)采煤工作面推进过程中,采空区围岩应力不断转移,引起围岩应力集中、影响范围增大,在上覆岩层重力的作用下,形成了环绕采空区的岩石压力拱,其空间形态近似为长轴在开采面推进向,短轴在工作面切眼向的隐形鸡蛋形厚壁压力拱结构。工作面推进开始后,在工作面走向剖面的压力拱由长轴在工作面的垂直向过渡到平行向,并保持;而工作面倾向剖面的压力拱始终保持长轴在垂直向。随采空区的增加,压力拱的外边界向深部岩体移动,压力拱拱体变厚,压力拱内的岩石应力增加。(2)工作面推进过程中数值逐渐增大,应力集中区域自采空面向周边扩展、向前推进、且不断变化。工作面推进距离相同时,近工作面巷道围岩应力曲线呈阶梯状变化,远工作面巷道围岩应力呈规则状的曲线变化,靠工作面帮围岩应力数值和增加梯度大于远工作面帮围岩;采矿动压引起工作面附近巷道围岩应力集中、弹性变形能积聚,具备发生冲击地压的应力条件。同时说明位于采煤工作面附近的采矿巷道处于应力增高的动压作用区,具备发生冲击地压的应力条件。(3)影响压力拱的主要因素有采矿工作面埋深、采空区宽度、采空区长度。当采空区宽度增加时,引起压力拱拱体厚度变大,上下位层岩中的拱体内边界外移;当采空区长度的增加时,导致上下位岩层内沿走向的压力拱内边界外移,而沿倾向的压力拱无变化;当工作面埋深能形成完整的压力拱后,增加埋深不会改变压力拱的空间形态,但拱内岩体应力随埋深的增大而增加。(4)采煤工作面推进过程中,围岩应力不断转移和调整,在层状岩体的一定范围内能形成动态的压力拱,其空间形态与演化规律与均质岩体的数值模拟结果相符较好。相似模拟试验再现了采空区覆岩运动和破坏的情景,冒落的宏观成拱效应明显。(5)压力拱演化规律研究成果应用于工程实践表明,某矿采空区在21141工作面推进前,压力拱的形态与已存在采空区的空间形态有关。采空区越长,压力拱的长轴越大,其扁平率就越小;随采场工作面的推进采空区的增大,采场压力拱呈现动态变化,压力拱的内外边界具有逐步向上扩展、向切眼前推进的特点。回采21141工作面形成的压力拱向采场集中轨道大巷转移,引起巷道围岩应力增加、弹性变形能积聚,巷道发生冲击地压的危险增加。(6)在工程应用中,基于压力拱内边界到巷道的距离、压力拱的拱体厚度,划分了某矿轴向轨道大巷的冲击地压危险区域,得到由高到低的顺序为:1375～1475 m段>1605～1615 m段>1135～1145 m段>1475～1525 m段>1275～1375 m段。为该矿发生冲击地压评价,采取防治措施,保证安全措施提供了一定依据。该论文有图63幅,表6个,参考文献143篇。更多还原

【Abstract】 The research on evolution laws of pressure arch in coal mining has important scientific value in solving bumping pressure and soft rock support in deep mining. Based on numerical simulation, scale physical model and on site engineering practice, the formation and evolution law of pressure arch in surrounding rock during coal mining is studied; influence factor of pressure arch is discussed; effect of mining dynamic pressure on the stability of surrounding rock and bumping pressure. And then the evolution law of pressure arch is applied in prevention practice of bumping pressure. The following important results and innovations are obtained.(1) During coal mining process, the stress in surrounding rock is transferred continuously, which causes the increase of the scope of tangential stress concentration in surrounding rock and forms the pressure arch supporting the upper weight of overlying strata around the gob area. The pressure arch is approximately egg-shaped and thick-wall pressure shell structure, with long axis in the trend of working face and short axis parallel to the open-off cut. After the advance of working face, the long axis of pressure arch which is in the section of strike turns into paralleling to the work face and maintains. However the arch which is in the section of dip will remain its long axis in the vertical direction. With the increase of working face’s driving distance, the outer boundary of pressure arch will extend, arch body will become thicker and stress within the arch body will increase.(2) With the advance of working face, stope stress increases gradually, stress concentration area advances and develops from the mined out area to surrounding area continuously. The stress value and its growth gradient in surrounding rock close to the face is greater than that in rock far away from the face.Stress distribution is linear in rock close to the working face, but curvilinear in rock far away. Mining dynamic pressure causes stress concentration, accumulation of elastic deformation energy and the possibility of bumping pressure. The egg-shaped spatial pattern of the arch also shows that the gate roadway is in the stress-increasing dynamic pressure area and bumping pressure is to be achieved.(3) The main factors of the pressure arch include depth of the mined out space, the width and length of the mined out space. When the width increases, the arch body will become thicker and the inner boundary of arch body will extend. When the length increases, the inner boundary of pressure arch along the strike will extend, whereas the arch pressure along the dip shift will not change. If the stope depth is large enough for the complete pressure arch, the increase of depth will not change its form, but the stress in the arch will increase.(4) With the advance of working face, the stress in surrounding rock will transfer and change continuously and pressure arch will be formed within a certain range of the heterogeneous rock mass. The space pattern and evolution law of the pressure arch is in consistent with the result of numerical simulation of homogeneous rock. Scale model test reproduces the movement and destruction of stope rock, the arching effect of in break is obvious.(5) Application of the evolution of pressure arch in project shows that before the advance of 21141 working face, the form of pressure arch was in connection with the spatial form of stope. The longer is the mined out area, the greater is the long axis, and the smaller is its flat rate. With the increase of the mined out area driving distance, the pressure arch showed dynamic change, its boundary extended forward and upward gradually. The pressure arch formed during the back stopping of 21141 working face transferred to track entry, which caused the increase of stress in the surrounding rock, the accumulation of elastic deformation energy and the raised risk of bumping pressure(6) In engineering applications, according to the space from inner boundary of arch to road way and the thickness of arch body, the dangerous area of track entry is divided based on dynamic pressure risk as the following order: 1375～1475 m >1605～1615 m>1135～1145 m>1475～1525 m>1275～1375 m. The research provides foundation for the evaluation, pevetion and control of rock burst to ensure safety of mine safety.更多还原