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．     

Structural motion of water-resisting key strata lying on overburden

Water-preserved mining is one of the important parts of the 'Green Mining' technological system. The purpose of wa-ter-preserved mining is to prevent water from bursting out in coal mines and thus to protect water resources. The principle of wa-ter-resisting key strata (WKS) is proposed to establish a model capable of guiding and developing water-preserved mining technol-ogy. The experimental model of the WKS is constructed following requirements of the Data Image Correlative Method (DICM).Five experimental schemes are designed according to different combined patterns of the WKS. The water-resisting performance of the WKS is analyzed from observation of structural stability. All of them provide referential value for water-preserved mining.     

巷道底板承压水突水评价方法研究

华北石炭二叠纪聚煤区是中国最重要的煤炭生产基地,区内众多煤矿皆受煤系底部奥陶系灰岩承压水威胁。针对当前煤矿巷道底板承压水突水评价方法存在的局限和不足,探索研究巷道底板承压水突水评价方法。现行评价方法岩梁法的理论计算前提主要包括：底板隔水层简化为两端固支梁;在岩梁弯矩最大处,底板隔水岩层承受的拉应力超过抗拉强度,岩层拉裂破坏;忽略孔隙水压力对岩石破坏的影响,计算隔水层厚度时抗拉强度取底板隔水层的平均值。事故数据及研究分析表明岩梁法计算假设存在不合理之处,与实际工况有较大偏差。基于对常见矩形巷道围岩应力分布特征的分析,结合巷道实际工况,摒弃底板隔水岩层弯拉破坏模式,提出隔水岩层剪切破坏模式,建立巷道底板承压水突水破坏岩柱模型;基于所建立的岩柱模型,利用极限平衡理论,综合考虑孔隙水压力对岩石破坏的影响,推导底板隔水层承受最大水压的计算评价方法。结果表明：最大水压与隔水层厚度、隔水层平均容重、抗剪强度参数、孔隙水压力系数和巷道宽度直接相关,最大水压与隔水层厚度呈指数函数关系。文中所提评价方法的计算结果与实测吻合,证明该方法合理有效。所提方法也能为地下工程其他专业领域类似的承压水突水问题研究提供借鉴。     

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.     

Discrimination conditions and process of water-resistant key strata

Water-preservation mining is one of the most important parts of the 'Green Mining' technology system,which can realize the effective regulation of groundwater resources by controlling strata movement,changing passive prevention and governance of water disasters to active conservation and utilization of groundwater resources and thus obtaining coal and water simultaneously in mining.The concept of water-resistant key strata further enriches the content of the key stratum theory and provides a theoretical basis for water-preservation mining.In order to realize the idea of water-resistant key strata as a guideline in the design of water-preservation mining and engineering applications,the conditions for discrimination in the process of water-resistant key strata,we have presented a mechanical model,as well as its corresponding computer program,based on a large number of theoretical analyses and field measurements,as well as on a comprehensive consideration of the position,structural stability and seepage stability of key strata.Practical engineering applications indicate that this discrimination method and its corresponding computer program on water-resistant key strata are accurate and reliable and can satisfy the actual design needs of water-preservation mining and thus have instructional importance for water-preservation mining in mining areas lacking water.     

瞬变电磁法在探测第四系底部砂层和黏土层分布中的应用

煤层顶板的砂层富水区和黏土隔水层分布规律的研究,对缩小防水煤柱、提高开采上限等有着至关重要的影响.探明直接覆盖在煤系地层之上的第四系底部砂层和黏土层的分布,可以有效地指导煤矿的防治水工作.瞬变电磁法近年广泛应用于煤矿富水区的探查,与其他方法相比,它具有低阻地质体反映灵敏,纵横向分辨率高,勘探深度大等优势.本文结合在山东...     

Pore structure characteristics of the relative water-resisting layer on the top of the Ordovician in Longgu Coal Mine

In order to study the permeability and water-resisting ability of the strata on the top of the Ordovician in Longgu Coal Mine, this paper tested the permeability and porosity of the strata, investigated the fracture and pore structure features of the strata, and identified the main channels which govern the permeability and water-resisting ability of the strata. The permeability of the upper, central and lower strata shows as 2.0504 × 10⁻³–2.782762 × 10⁻³, 4.1092 × 10⁻³–7.3387 × 10⁻³ and 2.0891 × 10⁻³–3.2705 × 10⁻³ μm², respectively, and porosity of that is 0.6786–0.9197%, 0.3109–0.3951% and 0.9829–1.8655%, respectively. The results indicate that: (1) the main channels of the relative water-resisting layer are the pore throats with a diameter more than 6 μm; (2) the major proportion of pore throats in the vertical flow channel and the permeability first increases and then sharply decreases; (3) the fractures occurring from the top to 20 m in depth of the strata were filled and there occurred almost no fracture under the depth of 40 m; and (4) the ratio of turning point of the main flow channel in the strata on top of Ordovician can be used to confirm the thickness of filled water-resisting layers.     

Mining-induced variation in water levels in unconsolidated aquifers and mechanisms of water preservation in mines

Phreatic water resources are widely found in thick unconsolidated surface layers in western China, where water levels respond sensitively and quickly to large-scale underground mining in conjunction with shallow coal seams. Longwall face #32201 of the Bulianta Coal Mine, in the Shendong coalfield was selected as an industrial trail base, where field observations on ground-water levels were conducted when the working face was below a water-rich area. The space-time variation in the behavior of un-consolidated water levels in response to underground mining and its relation with of advance were observed through the field trials. The basic conditions for water preservation in mines are presented and the mechanisms of water preservation in mining analyzed, given the geological condition of two key strata and a severely weathered layer buried in the overburden. The field trails show that water preservation in mining shallow coal seams can be successful under suitable conditions, providing new technology for envi-ronmental protection in the desert coalfields of northwestern China.     

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.     

基于隔水关键层突水系数法的海底隧道施工突水危险性分析

突水是海底隧道施工阶段最大的安全风险,而且突水事故多发生在不良地质段.为了更好地控制海底隧道不良地质体施工突水风险,本文对海底隧道的突水模式及其影响因素进行了分析,指出海底隧道突水事故多与隧道开挖引起的围岩变形破坏有关,而未破坏岩层的研究对于突水的控制至关重要.因而,重点对海底隧道不良地质体顶板突水机理进行分析,引入隔水关键层的概念及判别条件,将隔水层关键层突水系数作为海底隧道顶板突水判断标准,以厦门海底隧道左线F1风化槽为例,对隔水关键层突水系数的影响因素进行分析,并将突水系数法应用于F4风化槽突水预测,证实了突水系数法的可行性和适用性.     

Mechanisms of support failure and prevention measures under double-layer room mining gobs – A case study: Shigetai coal mine

In the practice of mining shallow buried ultra-close seams, support failure tends to occur during the process of longwall undermining beneath two layers of room mining goaf (TLRMG). In this paper, the factors causing support failure are summarized into geology and mining technology. Combining column lithology and composite beam theory, the key stratum of the rock strata is determined. A finite element numerical simulation is used to analyze the overlying load distribution rule of the main roof for different plane positions of the upper and lower room mining pillars. The tributary area theory (TAT) is adopted to analyze the vertical load distribution of each pillar, and dynamic models of coal pillar instability and main roof fracture are established. Through key block instability analysis, two critical moments are established, of which critical moment A has the greater dynamic load strength. Great economic losses and safety hazards are created by the dynamic load of the fracturing of the main roof. To reduce these negative effects, a method of pulling out supports is developed and two alternative measures for support failure prevention are proposed: reinforcing stope supports in conjunction with reducing mining height, or drilling ground holes to pre-split the main roof. Based on a comprehensive consideration of economic factors and the two categories of support failure causes, the method of reinforcing stope supports while reducing mining height was selected for use on the mining site.     

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.     

碳酸盐岩地层的岩性比率预测方法

实际工作中，井间或无井区目的层岩性比率的预测需借助于地震速度资料来实现，这对碳酸盐岩地层来讲更是如此，通过对速度谱资料进行倾角和地震－声波速度系统差校正，从而得到了可靠的地震原始层序层速度资料。在此基础上，建立了岩性预测的地震层序层速度模型及高、低速层压实模型，地质模型，等效模型，数学模型，通过这些模型对研究层中高速层的岩性比率进行了定量预测，最后在对研究层进行细分层的基础上，根据钻井统计的不同岩类的多少，将地层岩性简化为二元结构进行计算并校正，从而得到对应于高速层的碳酸盐岩的岩性比率，在塔里木盆地西南地区石炭系地层中，预测效果良好。     

Relationship between water inrush from coal seam floors and main roof weighting

A water-resistant key strata model of a goaf floor prior to main roof weighting was developed to explore the relationship between water inrush from the floor and main roof weighting. The stress distribution,broken characteristics, and the risk area for water inrush of the water-resistant key strata were analysed using elastic thin plate theory. The formula of the maximum water pressure tolerated by the waterresistant key strata was deduced. The effects of the caved load of the goaf, the goaf size prior to main roof weighting, the advancing distance of the workface or weighting step, and the thickness of the waterresistant key strata on the breaking and instability of the water-resistant key strata were analysed.The results indicate that the water inrush from the floor can be predicted and prevented by controlling the initial or periodic weighting step with measures such as artificial forced caving, thus achieving safe mining conditions above confined aquifers. The findings provide an important theoretical basis for determining water inrush from the floor when mining above confined aquifers.     

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.     

Mechanical model of control of key strata in deep mining

Based on the characteristic of deep rock layers and the theory of key strata, we analysed elastic mechanical characteristics of key strata by using elastic plate theory. The results show that the deformation and distribution of internal forces of key strata vary with different mine boundary conditions. The boundary values of key strata with three point boundaries and one fixed boundary is greater than that with four fixed boundaries. Considering the rheology of key strata under low stress conditions, we selected a generalized Kelvin model to analyse the theology characteristics of the key strata and discovered their instantaneous elastic phases. The rate of deformation decreased over time to the point where the key strata reached stability. But over this time, the effect on deformation became very clear.For high stress conditions, we chose a Burgers model and found deformation of key strata in the form of attenuation and steady-state creep and although the rate of deformation remained constant, secondary creep was obvious, causing instability in the system. As well, we analysed the effect of creep buckling and derived a relation between buckling force and time.     

采空区上覆岩层移动破坏动态力学模型的应用

采用采动岩体动态力学模型,对采动引起的覆岩移动破坏的时空规律进行了研究,结合兴隆庄矿５３０６工作面的地质、开采条件,对采动引起的断裂带发育发展规律,岩体内部离层发生发展规律、地表下沉规律等问题进行了分析,并对观测结果作出了较以前的各种理论模型更为符合实际的解释,该模型可在实际工作中得到了很好地应用。     

采场覆岩中复合关键层的形成条件与判别方法

在采场覆岩运动中起主要控制作用的岩层为关键层，而有时关键层是由2层或2层以上岩层形成的复合岩层所组成，我们称其为复合关键层．本文在深入揭示复合岩层形成机理的基础上，给出了形成复合岩层的力学条件与数学表达式，进而建立了采场覆岩中复合关键层的判别方法，并编写了复合关键层的判别程序．实例分析表明，复合关键层在岩层运动中是客观存在的，比同组岩层分开后的单一岩层的控制作用的线性叠加要大得多．本项研究是岩层控制的关键层理论研究的深入和发展，将有力促进岩层控制理论和技术的发展．     

Water-resisting ability of cemented broken rocks

Using the self-designed testing system, the seepage tests for cemented broken rocks were conducted, and the impact of different factors on water-resisting ability was analyzed. The results show that(1) seepage process of the cemented broken rocks can be divided into two categories: in one category, seepage instability occurs after a period of time, in the other, the permeability decreases slowly and tends to be stable,and seepage instability does not occur;(2) cementing performance of cementing agent and grain size distribution are the decisive factors for water-resisting ability, with the increase of cementing performance and the mass percentage of large grains, the water-resisting ability of the specimen strengthens;(3)aggregate type has little effect on seepage stability, for the specimens with different aggregate types,the permeability and the duration of seepage instability have small difference;(4) initial porosity has a certain effect on the water-resisting ability of the specimen, but has no decisive role. With the increase of the initial porosity, the duration of seepage instability decreases.     

巨厚松散层下条带开采地表沉陷机理及岩层移动模型的探讨

通过研究认为目前的岩层移动模型不能很好地分析巨厚松散层下条带开采岩土层的移动机理,对地表沉陷的主控因素和机理进行了理论分析和模拟试验,探讨了巨厚松散层下条带开采岩土层移动的复合介质模型.