Risk assessment of fault water inrush during deep mining

With the gradual depletion of shallow coal resources, the Yanzhou mine in China will enter the lower coal seam mining phase. However, as mining depth increases, lower coal seam mining in Yanzhou is threatened by water inrush in the Benxi Formation limestone and Ordovician limestone. The existing prediction models for the water burst at the bottom of the coal seam are less accurate than expected owing to various controlling factors and their intrinsic links. By analyzing the hydrogeological exploration data of the Baodian lower seam and combining the results of the water inrush coefficient method and the Yanzhou mine pressure seepage test, an evaluation model of the seepage barrier capacity of the fault was established. The evaluation results show the water of the underlying limestone aquifer in the Baodian mine area mainly threatens the lower coal mining through the fault fracture zone. The security of mining above confined aquifer in the Baodian mine area gradually decreases from southwest to northeast. By comparing the water inrush coefficient method and the evaluation model of fault impermeability, the results show the evaluation model based on seepage barrier conditions is closer to the actual situation when analyzing the water breakout situation at the working face.     

Overburden fracture evolution laws and water-controlling technologies in mining very thick coal seam under water-rich roof

Considering the danger of water inrush in mining very thick coal seam under water-rich roof in Majialiang Coal Mine, the universal discrete element (UDEC) software was used to simulate the overburden fracture evolution laws when mining 4# coal seam. Besides, this study researched on the influence of face advancing length, speed and mining height on the height of the water flowing fractured zones (HWFFZ), and analyzed the correlation of face advancing length and change rules of aquifer water levels and goaf water inflow. Based on those mentioned above, this research proposed the following water-controlling technologies: draining the roof water before mining, draining goaf water, reasonable advancing speed and mining thickness. These water-controlling technologies were successfully used in the field, thus ensured safely mining the very thick coal seam under water-rich roof.     

王河煤矿矿井突水特征与防治水对策

王河煤矿位于荥巩矿区中部,单一开采太原组一1煤层,属带压开采,为荥巩矿区矿井水害最为严重的矿井之一.该矿自投产以来累计发生突水事故达50余次,并造成淹井2次.本文通过对王河井田地质、水文地质条件、突水点分布规律和突水强度特征的分析研究,阐明了矿井突水事故频发的原因,论述了地质构造条件、一1煤层底板隔水层厚度、含水层富水性、矿山压力、水压与突水的关系.在此基础上,提出了矿井防治水害的方法和措施,为今后该矿的安全生产指明了方向.     

冯营矿矿井突水机理分析

针对冯营矿矿井水文地质条件复杂、水害严重的现状,研究了矿井充水水源、充水通道等充水条件,认为石炭系L8灰岩水、顶板砂岩空隙裂隙水和L2灰岩水是主要充水水源,断裂构造是主要的导水通道．研究表明：煤层顶板砂岩含水性相对较弱,太灰和奥灰含水层属中等-强富水性;断裂构造是沟通煤层底板太原组L8,L2灰岩和奥陶系（O2）灰岩的主要通道,也是矿井突水且突水量较大的主要因素之一．井田断层发育且导水良好,形成矿井突水的潜在威胁;对煤层底板采动裂隙影响的计算表明其有效隔水层较薄,加之矿压对底板的破坏,可构成煤层底板导水通道．以上因素导致冯营矿水害频发．     

五图-双系数法在煤矿突水评价中的应用

为安全开采受承压水威胁的一1煤层,分析了郑州矿区大平煤矿主要底板突水因素,并用单一突水系数公式对底板突水进行了预测分区.研究表明,用单一的突水系数公式来预测突水事故并不准确.在突水系数法的基础上,把含水层奥灰岩富水区、矿山压力、大中型断层、小断层密集带等主要突水因素考虑进去,对突水系数法进行修正,用五图-双系数法对大平矿底板突水进行预测分区,其预测结果可以指导煤矿安全开采.     

青东矿10煤层水文地质特征及充水因素分析

为了评价10煤层开采可能产生的水害影响,根据矿井含、隔水层的水文地质特征,指出10煤层受采动破坏,顶底板砂岩裂隙水、太原组和奥陶系岩溶水沿采动裂隙和断层溃入矿井,对矿井开采形成威胁。根据对矿井充水因素的分析,得出矿井的充水强度不大,充水通道主要为隔水层薄弱地段采动裂隙和断层破碎带。     

Mechanism of mine water-inrush through a fault from the floor

The mechanism of mine water inrushes in coal mines in China differs considerably from that in other countries. In China, most water inrushes occur from floor strata, where the water-inrush sources are karstic limestone aquifers. Our study describes the mechanism of mine water inrushes through a fault in the mine floor using principles of strata mechanics and the path of water inrush from an aquifer to the working face. A criterion to judge whether a ground water inrush will occur through a fault or not is also described, together with a case history of water inflow in the Feicheng coalfield, China.     

Time-domain characteristics of overlying strata failure under condition of longwall ascending mining

Ascending mining is one of the most effective ways to solve problems of water inrush, gas outburst and rock burst in coal seams mining. In order to reveal the law of motion and spatiotemporal relationship of overlaying strata, field measurement has been done in a mine. Long distance drillings were constructed from 4# coal seam to 6# coal seam at several certain typical positions, and movement and failure law of overlying strata after mining was analyzed by drilling video and observing the fluid leakage. Besides, we also analyzed the spatiotemporal development law of overlying strata failure with different mining heights and time intervals in the lower coal seam. The results show that: ascending mining is significantly affected by time-domain characteristics of overlaying strata failure after the lower coal seam’s mining, height equations of caving zone and fractured zone are given in this paper, and the feasibility of ascending mining was compartmentalized concretely according to the spatiotemporal relationship. Research methods and conclusions of this paper have certain referential significance for the study of ascending mining, mining under water, mining under building, mining under railway and stress-relief mining.     

Evolution and modeling of mine water inflow and hazard characteristics in southern coalfields of China: A case of Meitanba mineOA

In this paper, the hydrogeological characteristics in the southern coalfields of China are first briefly outlined. Then, taking the Meitanba mine as an example, the evolution and modeling of mine water inflow are studied. Finally, the hazard characteristics related to mine water and mud inrush are analyzed. The results show that the main mine water sources in the Meitanba mine area are groundwater, surface water and precipitation. The evolution of mine water inflow with time indicates that the w...     

承压水上煤层底板采动效应数值模拟研究

针对淮南煤田某矿412采区开采1煤时受承压水的威胁,从采区的水文地质与工程地质条件出发,建立数值计算模型,并利用FLAC数值分析软件对开采过程中煤层底板应力、破坏区及突涌水情况进行分析与评价,为安全开采提出相应建议.     

Forecasting water disaster for a coal mine under the Xiaolangdi reservoir

Xin'an coal mine, Henan Province, faces the risk of water inrush because 40% of the area of the coal mine is under the surface water of the Xiaolangdi reservoir. To forecast water disaster, an effective aquifuge and a limit of water infiltration were determined by rock-phase analysis and long term observations of surface water and groundwater. By field monitoring, as well as physical and numerical simulation experiments, we obtained data reflecting different heights of a water flow fractured zone (WFFZ)under different mining conditions, derived a formula to calculate this height and built a forecasting model with the aid of GIS. On the basis of these activities, the coal mine area was classified into three sub-areas with different potential of water inrush. In the end,our research results have been applied in and verified by industrial mining experiments at three working faces and we were able to present a successful example of coal mining under a large reservoir.     

郭二庄9~#煤带压开采底板突水灰色风险评价

针对郭二庄井田下组9#煤带压开采中存在的底板突水风险影响因素的不确定性,采用灰色风险计算模型和方法,结合井田已有突水、出水点水位标高、矿井最大涌水量及单位涌水量等相关信息统计,构建灰色风险计算模型,对井田受采动影响后煤层底板发生突水风险的概率和风险性变异进行评价。计算结果表明郭二庄井田下组9#煤带压开采存在底板突水风险性大,煤层开采前应慎重作出避让和分区隔离开采、探治结合等有效的补救措施,减少突发水害事故的发生。     

郭二庄9#煤带压开采底板突水灰色风险评价

针对郭二庄井田下组9#煤带压开采中存在的底板突水风险影响因素的不确定性,采用灰色风险计算模型和方法,结合井田已有突水、出水点水位标高、矿井最大涌水量及单位涌水量等相关信息统计,构建灰色风险计算模型,对井田受采动影响后煤层底板发生突水风险的概率和风险性变异进行评价。计算结果表明郭二庄井田下组9#煤带压开采存在底板突水风险性大,煤层开采前应慎重作出避让和分区隔离开采、探治结合等有效的补救措施,减少突发水害事故的发生。     

Numerical simulation of dewatering thick unconsolidated aquifers for safety of underground coal mining

With an increase of mining the upper limits under unconsolidated aquifers, dewatering of the bottom aquifer of the Quaternary system has become a major method to avoid water and sand inrushes. In the 8th District of the Taiping Coal Mine in south-western Shandong province, the bottom aquifer of the Quaternary system is moderate to excellent in water-yielding capacity. The base rock above the coal seam is very thin in the concealed coal field of the Carboniferous and Permian systems. Therefore, a comprehensive dewatering plan from both the ground surface and the panel was proposed to lower the groundwater level in order to ensure mining safety. According to the hydrogeologic conditions of the 8th District, we established a numerical model so that we could simulate the groundwater flow in the dewatering process. We obtained the simulation parameters from previous data using backward modeling, such as the average coefficient of permeability of 12 m/d and the elastic storage coefficient of 0.002. From the same model, we predicted the movement of groundwater and water level variables and obtained the visible effect of the dewatering project. Despite the overburden failure during mining, no water and/or sand inrush occurred because the groundwater level in the bottom aquifer was lowered to a safe water level.     

孙疃煤矿1028工作面底板突水特征与水源识别

在研究孙噎煤矿地质条件及水文地质特征的基础上,对1028工作面底板突水特征、水化学特征、含水层水位动态变化,得出1028工作面突水水源主要来源于10煤上下砂岩裂隙水,太原组灰岩上、中含水层段水是主要补给水源,与第四含水层和太原组灰岩下含水层段无关。     

卧龙湖煤矿8101工作面采动覆岩破坏特征研究

煤矿开采过程中覆岩破坏容易引发工作面溃砂、突水事故,为了保证卧龙湖煤矿8101工作面安全开采,根据矿区覆岩工程地质特征及矿区岩层柱状图,建立了FLAC3D数值模拟模型.通过FLAC3D软件模拟,得到了工作面推进时的覆岩应力场及覆岩塑性区分布图,由此分析得出在开切眼和煤壁处覆岩主要为剪切破坏,采空区上部主要为拉伸破坏,得到煤层开采时覆岩最大主应力1.78MPa,最大导水裂隙带高度31m.     

Numerical analysis of water inrush from working-face floor during mining

Confined water in the Ordovician limestone is one of the hidden troubles that threaten safe production of mines in north China. A numerical model of the key strata was developed. It included the structural characteristics and mechanical properties of the floor rock at the working face of a particular coal mine. The model was used to predict failure modes and to help establish rules for safe mining above the aquifer. The distribution of deformation, failure and seepage was simulated by using Dilian Mechsoft's Rea- listic Failure Process Analysis (RFPA2D) program. The stress distribution, the deformation and the flow vectors were also obtained. The results indicate that: 1) The original balance of the stress and seepage fields is disturbed due to coal mining; and 2) As the working face advances different deformation, or failure, appears in the surrounding rocks, the water-resisting strata in floor may be destroyed and the passage of water from the aquifer into the mine may occur. The combined action of mining stress and water pressure ultimately lead to water inrush from the floor.     

淮北矿区煤层底板突水的岩体结构控制研究

淮北矿区位于华北聚煤区南部,其水文工程地质环境具有华北煤田的基本特征,水文地质条件复杂,山西组煤层开采普遍受到底板灰岩水的严重威胁,曾发生多次底板突水事故。本文介绍了淮北矿区煤系水文地质与工程地质特征,并对研究区底板突水典型案例进行了系统分析,揭示了不同的底板地质构造条件和突水通道所导致的突水特征的差异性,对于认识底板突水的岩体结构控制具有典型意义。     

基于GSM水位遥测系统的大型放水与示踪联合试验

鹤壁矿区寺湾煤矿主采煤层为石炭系太原群下夹煤岩,顶板为太原群第2层薄层灰岩岩溶水(二灰水)承压含水层.为安全采煤,须提前疏放.为预测矿井正常涌水量,了解二灰水和奥陶系灰岩岩溶水(奥灰水)间的水力联系,进行了大型放水与示踪联合试验,水位的观测采用了煤科院西安分院研制的水位自动遥测系统,试验数据丰富且可靠.试验证实:二灰水单位降深涌水量为12.29 m3/(h.m),F8断层是导水断层,断层东翼的奥陶系灰岩溶水侧向补给西翼的二灰水.采用相关曲线外推法、漏斗均衡法、解析法和数值法预测矿井正常涌水量为1 400 m3/h.     

后生冲蚀对矿井瓦斯突（喷）出的控制作用

针对新景矿3号煤层冲蚀带较易引发瓦斯突（喷）出的特殊情况,对煤层段岩性组合特征进行了分类研究．认为在构造破坏不甚严重的情况下,后生冲蚀导致的煤层段岩性组合的明显差异是矿井瓦斯突（喷）出频发的主要控制因素之一．在详细研究已采区冲蚀带物性响应特征和钻孔、采掘工程揭露,理清冲蚀带宏观分布特点的基础上,依据三维地震勘探和钻孔资料对未采区冲蚀带进行了圈划,为矿井瓦斯突（喷）出预测及防治提供了依据．