初采覆岩破坏性影响区的解析高度

以现场实测资料和实际的开采条件为依据，建立回采工作面覆岩破坏的力学模型，分析初次开采时顶板最大冒落高度与采高、采深、顶板岩层的力学性质、采空区大小及顶板岩层的碎胀性之间的关系。利用微分方程求出初采覆岩破坏性影响区高度的解析解。     

采场上覆岩层的平衡条件

根据实际测定的采场上覆岩层的移动曲线，以及在一定条件下采场上覆岩层有可能形成“结构”的实际现象,本文提出了采场上覆岩层形成“结构”的力学模型。由此力学模型人们可以得出上覆岩层形成结构的平衡条件。根据分析,这些条件紧密地与上覆岩层的厚度、采高、直接顶的总厚度、管理顶板的方法以及上覆岩层的力学性质有关。     

采动覆岩离层及其分布规律

本针对覆岩注浆减缓矿山开采沉陷问题，从理论上探讨了采场上覆岩层内部产生离层的力学条件，离层分布规律及离层空间体积的计算方法。     

五沟煤矿导水裂隙带发育高度预测

煤层开采导致覆岩产生移动变形破坏,描述覆岩破坏影响程度的导水裂隙带发育高度是评价顶板是否发生突水溃砂等灾害事故的重要指标之一,因此对影响导水裂隙带发育高度的采高、工作面几何参数、覆岩岩性及岩层结构等主要因素进行分析,利用模糊数学方法将非线性问题转换成线性问题进行计算,获得五沟煤矿10煤开采导水裂隙带发育高度预测公式,为五沟煤矿含水层下10煤层的安全开采提供指导。     

大采深条件下导水裂隙带高度计算研究

在分析导水裂隙带高度计算经验公式来源背景的基础上,阐明了只考虑采厚单因素计算导水裂隙带高度的经验公式不合理性及其应用的局限性,针对大采深条件下工作面覆岩运动的特点,基于采场顶板"上四带"划分理论,推导出了考虑开采厚度、开采深度、工作面跨度、岩石的力学性质、岩层的组合特征、含水层水压等因素的导水裂隙带理论计算公式.结果表明:大采深条件下,工作面跨度对裂隙带高度发育有控制作用,含水层水压对导水裂隙带高度发育有促进作用,结合鲍店煤矿1303工作面开采实例,说明获得的理论公式可应用性.     

岩层与地表移动问题的力学模型的选择

岩层与地表移动是一个发展的过程，从开始开采到移动结束，岩的特性发生了很大的改变，使用力学模型 解决岩层与地表移动问题必须使模型简化，但应满足合理的工程精度要求，否则将导致结论的谬误，在反算岩移参数时，可以使用采前的力学模型把开采作为边界条件模拟输入，也可使用采后的力学模型，即岩体已形成了三带，采后的力学模型由于已将来空区考虑为被岩石充填，故计算的应力可能异于顶板尚未冒落的岩体的应力，在承压水上开采     

厚煤层不同开采方法覆岩破坏规律研究

在对不同开采方法覆岩破坏高度实测资料分析对比的基础上，研究了冒落岩层高度及碎胀性与覆岩破坏高度的关系，探讨了开采方法对覆岩破坏高度的影响，其结论对于覆岩破坏理论研究及水体下采煤实践具有促进与指导意义．     

重复采动停采边界关键层失稳诱发灾害研究

基于岩层控制的关键层理论,分析了重复采动过程中上覆巨厚关键层岩块形态特征、冒落和移动规律.结果表明:重复采动停采边界矿震机理归结为2种形式:1)采高增加引起顶板冒落高度增加,造成高位关键岩块铰接平衡结构失稳诱发矿震;2)重复采动引起顶板岩层移动线外扩,导致采场边界顶板活动范围增加,造成高位关键层破断诱发矿震.依据此机理,提出了降低推采速度(低扰动)、优化开采边界(低应力)等防控动力灾害的技术方法.通过3下510工作面实施运用与开采实践,达到了采场边界矿震及动力灾害的防控目的,保证了工作面安全和地面稳定.     

顶板隔水层关键层耦合作用规律研究

在煤矿开采过程中，如果覆岩裂隙扩展至贯穿隔水层，则会诱发地下水或地表水大量涌向采场，导致煤矿淹井事故．利用RFPA^2D-Flow软件建立了隔水层关键层耦合的采场推进模型，计算并分析了裂隙场的发育和分布，绘制了顶板水渗流量曲线．讨论了与裂隙发育密切相关的覆岩支承压力与中间岩层厚度、关键层厚度及破断闻的关系．结果表明：关键层未破断时，中问岩层厚度对隔水层裂隙发育作用不明显；厚关键层对隔水层能起较好的保护作用．     

厚煤层不同开采方法覆岩破坏规律研究

在对不同开采方法覆岩破坏高度实测资料分析对比的基础上,研究了冒落岩层高度及碎胀性与覆岩破坏高度的关系,探讨了开采方法对覆岩破坏高度的影响,其结论对于覆岩破坏理论研究及水体下采煤实践具有促进与指导意义.     

Mechanical mechanism of overlying strata breaking and development of fractured zone during close-distance coal seam group mining

This study mainly investigates the mechanical mechanism of overlying strata breaking and the development of fractured zones during close-distance coal seam group mining in the Gaojialiang coal mine. First,a mechanical model for the second ‘‘activation" of broken overlying strata is established, and the related mechanical ‘‘activation" conditions are obtained. A recursive formula for calculating the separation distance of overlying strata is deduced. Second, a height determining method for predicting the height of fractured zones during close-distance coal seam group mining is proposed based on two values, namely,the separation distance and ultimate subsidence value of overlying strata. This method is applied to calculate the fractured zone heights in nos. 20107 and 20307 mining faces. The calculated results are almost equal to the field observation results. Third, a modified formula for calculating the height of a waterflowing fractured zone is proposed. A comparison of the calculated and observed results shows that the errors are small. The height determining method and modified formula not only build a theoretical foundation for water conservation mining at the Gaojialiang coal mine, but also provide a reference for estimating the height of water-flowing fractured zones in other coal mines with similar conditions.     

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.     

采动覆岩破断裂隙的贯通度研究

为了判定采场隔水关键层和计算导水裂隙带高度,进行了覆岩采动导水裂隙分布特征的相似模拟实验和力学分析.提出了破断裂隙贯通度的概念和计算公式.试验结果表明,采场覆岩裂隙带上位岩层的回转变形空间较小,且由于岩层刚度和厚度的差异,薄岩层会完全破断;但坚硬厚岩层破断裂隙未贯通,没有形成竖向"导水、导气"裂隙.为了描述岩层的破断程度及破断裂隙导水能力的强弱岩层破断裂隙的贯通度随其下自由空间的增大而增大,且存在自由空间阀值,大于其阀值时则增加缓慢并趋于1;随岩层厚度增大,起裂时岩层破断裂缝的张开角度减小;岩层破断裂隙的贯通度随裂纹尖端临界张开位移的增大而呈线性减小,随岩层周期破断距的增大也呈近似线性减小.     

Mechanism of rock burst caused by fracture of key strata during irregular working face mining and its prevention methods

To study the occurrence mechanism of rock burst during mining the irregular working face, the study took irregular panel 7447 near fault tectonic as an engineering background. The spatial fracture characteristic of overlying strata was analyzed by Winkler elastic foundation beam theory. Furthermore, the influence law of panel width to suspended width and limit breaking span of key strata were also analyzed by thin plate theory. Through micro-seismic monitoring, theoretical analysis, numerical simulation and working resistance of support of field measurement, this study investigated the fracture characteristic of overlying strata and mechanism of rock burst in irregular working face. The results show that the fracture characteristic of overlying strata shows a spatial trapezoid structure, with the main roof being as an undersurface. The fracture form changes from vertical “O-X” type to transverse “O-X” type with the increase of trapezoidal height. From the narrow mining face to the wide mining face, the suspended width of key strata is greater than its limit breaking width, and a strong dynamic load is produced by the fracture of key strata. The numerical simulation and micro-seismic monitoring results show that the initial fracture position of key strata is close to tailgate 7447. Also there is a high static load caused by fault tectonic. The dynamic and static combined load induce rock burst. Accordingly, a cooperative control technology was proposed, which can weaken dynamic load by hard roof directional hydraulic fracture and enhance surrounding rock by supporting system.     

Fracturing,caving propagation and influence of mining on groundwater above longwall panels——a review of predictive models

Historically there have been a number of different hypotheses and empirical models developed in an attempt to describe the nature of fracturing above longwall panels in underground coal mining. The motivation for such models varies, ranging from understanding the impact of mining on surface subsidence,to back-analysis of caving behaviour in the immediate roof behind the longwall face. One of the most critical motivating factors that is taking on increased importance in many coalfields, is the need for better understanding, and hence prediction of the impact of mining on overlying strata, particularly strata units acting as aquifers for different groundwater horizons. This paper reviews some of the major prediction models in the context of observed behaviour of strata displacement and fracturing above longwall panels in the southern coalfields of New South Wales, south of Sydney. The paper discusses the parameter often referred to as ‘‘height of fracturing" in terms of the critical parameters that influence it, and the relevance and appropriateness of this terminology in the context of overlying sub-surface subsidence and groundwater impact. The paper proposes an alternative terminology for this parameter that better reflects what it is and how it is used. The paper also addresses the potential role of major bedding shear planes mobilised by mining and their potential influence on overlying subsidence and groundwater interference.     

Characteristics of mining gas channel expansion in the remote overlying strata and its control of gas flow

The technology of pressure relief gas drainage is one of the most effective and economic for preventing gas emissions in underground mines. Based on current understanding of strata breakage and fracture development in overlying strata, the current study divides the overlying strata into the following three longitudinal zones in terms of the state of gas flow: a turbulent channel zone, a transitional circulation channel zone and a seepage channel zone. According to the key strata discrimination theory of controlling the overlying strata, the calculation method establishes that the step-type expansion of the mining gas channel corresponds to the advancing distance of working face, and this research also confirms the expanding rule that the mining gas channel in overlying strata follows the advancing distance of mining working face. Based on the geological conditions of Xinjing Coal Mine of Yangquan, this paper researches the expanding rule of mining gas channel as well as the control action of the channel acting on the pressure relief flow under the condition of the remote protective layer, and got the distance using inversion that the step-type expanding of mining gas channel is corresponding to the advancing distance of working face, which verifies the accuracy and feasibility of theoretical calculation method proposed in this study. The research provides the theoretical basis for choosing the technology of pressure relief gas drainage and designing the parameters of construction.     

Mechanics criterion and factors affecting overburden stability in solid dense filling mining

The effect of controlling strata movement in solid filling mining depends on the filling rate of the goaf.However, the mechanical property of the overburden in the backfill stope and the designed size of the backfill mining workface should also be considered. In this study, we established a main roof strata model with loads in accordance with the theory of key strata to investigate the stability of the overburden in solid dense filling mining. We analyzed the stress distribution law of the main roof strata based on elastic thin plate theory. The results show that the position of the long side midpoint of the main roof strata failed more easily because of tensile yield, indicating that this position is the area where failure is likely to occur more easily. We also deduced the stability mechanics criterion of the main roof strata based on tensile yield criterion. The factors affecting the stability of the overburden in solid dense filling mining were also analyzed, including the thickness and elasticity modulus of the main roof strata, overlying strata loads, advanced distance and length of workface, and elastic foundation coefficient of backfill body.The research achievements can provide an important theoretical basis for determining the designed size of the solid dense filling mining workface.     

薄基岩条带开采工程地质力学模型试验研究

针对兖州太平矿区内赋存有薄基岩的地层条件，以工程地质力学模型试验为手段，研究了薄基岩条件下条带开采覆岩与地表移动变形及破坏的工程地质机理及其主控因素，揭示了薄基岩条带综放开采引起的上覆岩层的破坏过程、破坏形态、破坏范围及地表的移动变形规律，为工程实践提供了理论依据。     

Structure and deformation measurements of shallow overburden during top coal caving longwall mining

Mining induced pressures are strong and overburden failure areas are large in top coal caving longwall mining, which constrains high production and safety mining. By employing the combination of the full view borehole photography technique and the seismic CT scanner technique, the deformation and failure of overlying strata of fully mechanized caving face in shallow coal seam were studied and the failure development of overburden was determined. Results show that the full view borehole photography can reveal the characteristics of strata, and the seismic CT scanner can reflect the characteristics of strata between the boreholes. The combined measurement technique can effectively determine the height of fractured and caved zones. The top end of the caved zone in Yangwangou coal mine employing the top coal caving longwall mining was at the depth of 171 m and fractured zone was at the depth of 106-110 m. The results provide a theoretic foundation for controlling the overburden strata in the shallow buried top coal caving panel.     

Fissure evolution and evaluation of pressure-relief gas drainage in the exploitation of super-remote protected seams

Based on nonlinearity contact theory and the geological structure of the Xieqiao Coal Mine in the newly developed Huainan coal field, rock movements, mining fissures and deformation of overlying strata were simulated by using the interface unit of FLAC3D to evaluate the pressure-relief gas drainage in the exploitation of super-remote protected seams. The simulation indicates that the height of the water flowing fractured zone is 54 m in the overlying strata above the protective layer. The maximum relative swelling deformation of the C 13 coal seam is 0.232%,while the mining height is 3.0 m and the distance from the B8 roof to the C13 floor is 129 m, which provides good agreement with a similar experiment and in situ results. The feasibility of exploitation of a super-remote protective coal seam and the performance of the pressure-relief gas drainage in a super-remote protected layer are evaluated by comparisons with practice projects. It demonstrates that the relieved gas in the super-remote protected layers could be better drained and it is feasible to exploit the B8 coal seam before the C13 super-remote protected coal seam. The method is applicable for the study of rock movements, mining fissures and deformation of the overburden, using the interface unit to analyze the contact problems in coal mines.