【作者】 王旭宏；

【导师】 康立勋；

【作者基本信息】 太原理工大学 ， 岩土工程， 2010， 博士

【摘要】 冲击地压是煤矿重大动力灾害之一。大同矿区顶、底板及煤层都坚硬,是我国典型的“三硬”煤层条件的矿区。目前冲击地压已成为困扰大同矿区安全、高效生产的瓶颈之一,而对于这种条件下冲击地压发生机理的研究却鲜见报道。本文在总结已有研究成果的基础之上,结合大同矿区的实际情况,开展了现场调研、冲击地压影响因素分析、冲击倾向性测定与研究、地应力测定与分析、数值模拟等相关工作,系统研究了“三硬”煤层条件下冲击地压发生的机理,为“三硬”煤层条件下冲击地压现象的控制与防治提供理论基础,并取得了以下主要成果与结论：(1)对大同矿区忻州窑矿、同家梁矿、煤峪口矿三矿的煤层及顶底板进行了物理力学性质测定和冲击倾向性判定,并对现行的冲击倾向性鉴定指标进行了研究,提出了新的冲击倾向性判定指数——剩余能量释放速度指数。(2)采用空心包体应变计的方法现场测量地应力,测定结果表明大同矿区水平构造应力较大,水平构造应力占主导地位,最大水平挤压应力方向基本上为SE—NW向,走向位于N-W和NN-W向,在324.9°-331.7°范围内变化；其最大水平主应力数值大小在12.05MPa-13.11 MPa范围内变化。四个测点的侧压系数在1.500-1.789范围内变化。(3)通过数值模拟可以看出构造应力对冲击地压的产生具有较大的影响：在构造应力作用下,煤岩体更容易形成应力集中,产生冲击地压；对于巷道而言,当主应力垂直于巷道轴向时,巷道煤壁附近容易形成较大的水平应力梯度,使得煤岩更容易产生冲击地压,因此在巷道开拓布置时应注意不要与最大水平主应力方向垂直布置。(4)大同矿区冲击地压除了具有冲击地压的一般特征(突发性、多样性、复杂性、破坏性)外,带有鲜明的大同特色,即三硬、冲击地压显现地点埋深较浅、下分层开采时巷道发生冲击大于上分层开采时等。(5)根据大同矿区冲击地压显现特征,将大同矿区冲击地压分为四种基本类型：两帮煤层冲击、底板冲击、两帮及底板冲击和小块状弹射。(6)研究了冲击地压的影响因素,主要包括自然地质条件和开采技术条件两大方面的因素,大同矿区所发生的冲击地压是受着两方面的因素影响造成的。(7)引起大同矿区采准巷道两帮冲击的主要原因是：采煤方法、煤体应力和支护强度及采动影响。(8)“三硬”条件下,随着采空区面积的不断扩大,在巷道周围的煤柱上形成很高的支承压力,造成对煤层的夹持作用,顶板的震动与反弹使煤壁与顶板之间形成离层。(9)建立数学力学模型与应用数值模拟,研究了煤壁整体推出型冲击地压发生机理。在巷帮一定深度存在或产生垂直裂隙的情况下,巷帮水平位移与水平载荷基本呈线性正比关系,顶底板与煤层分离时的水平位移大于未分离时的水平位移,并且前者比后者位移增长速度快。(10)用关键层理论分析了坚硬底板冲击现象,找出了其影响因素。通过数值模拟分析,认为随着巷道宽度的增加,水平拉应力最大值向底板深部发展,将引起底板中关键层突然断裂,最终导致冲击地压的发生。论文的创新点如下：(1)首次提出“三硬”冲击地压概念,阐明大同矿区的冲击地压特征,对“三硬”浅埋条件下发生的冲击地压进行了分类,研究了冲击地压的影响因素。(2)首次研究了煤壁整体推出型冲击地压发生机理,通过建立数学力学模型与数值模拟分析,找出了冲击发生的条件和规律。(3)首次用关键层理论分析了坚硬底板冲击现象,找出了其影响因素。通过数值模拟分析,找出了冲击发生的条件。更多还原

【Abstract】 Rock burst is one of the major dynamic disasters of coal mine. Datong Coal Mining Area with the hard seam, the hard roof, and the hard bottom is a typical one under the condition of "three-hard" coal seam. At present rock burst is a key factor which restricts safe and efficient production in the area,but the research on the mechanism of rock burst occurring in this condition is hardly found. Based on the existing research results and combined with the actual situations of Datong Coal Mining Area, this thesis, through on-the-spot investigation, analysis of influence factors of rock burst, measurement and research on the bursting liability and ground stress, as well as numerical simulation, studies the mechanism of rock burst’s occurrence under the condition of "three-hard" coal seam in a systematic manner, so as to provide theoretic bases for the control and prevention of rock burst occurring in the condition. The following main conclusions have been drawn:(1) By determination of physical and mechanical properties and judgment of bursting liability of coal, roof and floor of Xinzhou, Tongjialiang and Meiyukou Coal Mine in Datong Coal Mining Area, and research on current identification indicators of bursting liability, this thesis proposes new index of bursting liability, dump energy delivery speed index.(2) Ground stress is measured on site with the method of hollow inclusions strain gauge. The results of test show that the horizontal tectonic stress is comparatively large and dominant in Datong Coal Mining Area, and the direction of maximum horizontal compression stress is basically SE—NW, and its alignment is in between N-W and NN-W,and its maximum changes between 324.9°-331.7°. The lateral pressure coefficients of four measuring point change between 1.500-1.789.(3) Numerical simulation has discovered that tectonic stress has a great influence on rock burst. Under the action of tectonic stress, coal and rock will form stress concentration and cause rock burst more easily. As for the tunnel, when the direction of principal stress is perpendicular to axial of tunnel, the vicinage of coal wall will form larger horizontal stress gradient and cause rock burst easily. Therefore, it must be noted that the tunnel should not be perpendicular to the direction of maximum horizontal stress when it is arranged.(4) Rock burst in Datong Coal Mining Area has not only general characteristics of rock burst (suddenness, diversity, complexity, destructiveness), but also distinct characteristics of Datong, i.e. three-hard, shallow show site of rock burst, rock burst occurring in the next hierarchical tunnel greater than in the previous one etc.(5) According to the features of rock burst in Datong Coal Mining Area, rock burst in this area can be divided into four basic types, i.e. two coal walls burst, floor burst, two coal walls and floor burst, and small block ejection.(6) The thesis studies the influence factors of rock burst, which mainly includes two major factors, i.e. natural geological conditions and mining technology conditions. Rock burst occurring in Datong Coal Mining Area is affected by both factors.(7) The main reasons causing the two walls burst of tunnel in Datong Coal Mining Area includes mining method, stress of coal, support intensity and impact of mining.(8) Under the condition of "three hard", it is thought that with the expansion of the mined-out area, high pressure, which is imposed on the pillar around tunnel, will make clamping effect on coal seam. Vibration and rebound of the roof will cause separation between the wall and the roof.(9) The mathematical and mechanics model is established, numerical simulation is applied, and the rock burst mechanism of the overall removal of coal tunnel wall is studied in the thesis.Under the condition that vertical cracks exist or will appear in a certain depth of the tunnel walls, horizontal displacement of the tunnel walls is basically proportional to horizontal load, and horizontal displacement during the coal bed being separated from the roof and the floor is much more obvious than the horizontal displacement with no separation. Besides, the former grows much faster than the latter.(10) The phenomenon of hard floor burst is explained in the theory of Key Layer, and influence factors are finally found out. After analysis of numerical simulation, the thesis considers that with the increase of tunnel width, maximum horizontal tensile stress occurs in deeper position of the bottom, and it will cause sudden fracture of floor key layer, and eventually lead to the occurrence of rock burst.New points of the thesis are as follows:(1) For the first time, the thesis proposes the conception of rock burst of "three hard",and clarifies the features of rock burst in Datong Coal Mining Area. The rock burst with conditions of "three-hard"and shallow is classified,and the influence factors are studied.(2) For the first time, the rock burst mechanism of the overall removal of coal tunnel wall is studied. With the establishment of mathematical and mechanics model and analysis of numerical simulation, the conditions and the laws of rock burst are found.(3) For the first time, the phenomenon of hard floor burst is explained in the theory of Key Layer, and influence factors are found out. With the analysis of numerical simulation, the conditions of rock burst are found out.更多还原