Height of the Water-Flowing Fractured Zone of the Jurassic Coal Seam in Northwestern China

Research on the height of the water-flowing fractured zone (HWFFZ) is important for mine safety and regional eco-environmental conservation in the Jurassic coal field of northwestern China. Using the Cuimu coal mine as a case study, on-site measurement, mechanical theory calculation, and numerical simulation were used to analyze the regularity of the HWFFZ in this area. A television borehole wall imaging system with a light source allowed us to examine the size and shape of fissures intuitively, allowing the top boundary of the HWFFZ to be determined. Per mechanical theory, the overlying strata in the decreasing stress zone was simplified as a clamped rectangular plate and the formula for calculating HWFFZ was obtained by comparing the value of the ultimate deflection of the thin plate and the height of the free space in the lower part of the stratum. In addition, the dynamic development of the HWFFZ was simulated using realistic failure process analysis software. The unusual characteristics of the HWFFZ were analyzed from two aspects: the inapplicability of the traditional empirical formula and the difference of the overlying strata structure of the Jurassic and the Carboniferous Permian coalfields. These strata can be divided into layered and integrated strata in the Jurassic coalfield.     

巨野煤田主采煤层导水裂缝带高度探测研究

利用＂双端多回路注（放）水系统＂探测导水裂缝带的发育高度,根据现场的实际测试资料分析,得出巨野煤田首采工作面采后覆岩裂缝带呈现整体连续性特征和裂采比,为同类矿井开采安全性评价和安全生产提供了科学的研究方法和参考依据。     

Predicting the Height of the Water-Conducting Fractured Zone in Fully Mechanized Top Coal Caving Longwall Mining of Very Thick Jurassic Coal Seams in Western China Based on the NNBR Model

The focus of China’s coal mining in recent years has shifted to western China, which has a fragile ecological environment. The Jurassic coal in this area is buried at shallow depths and is very thick. Currently, the two main issues are the inrush of underground water and the disruption to shallow surface water supplies brought on by mining. Accurately predicting the height of the water-conducting fractured zone (WCFZ) is the key to preventing roof water damage and attaining water conservation in this mining area. A nearest neighbor bootstrap regression (NNBR) model was established to predict the height of the WCFZ for working face 117 of the Jinjitan coal mine in western China, which uses fully mechanized top coal caving longwall mining. The model was verified based on the measured heights of the WCFZ (30 groups of measured data) using the actual mining thickness (> 8 m) and working face width as predictive factors. The mean error of the model’s prediction was 1.5 m and the mean absolute percentage error was 13.6%, which was better than the result predicted using the established conventional empirical formula. The model was improved by applying a safety factor of 1.3, which met the 96.7% reliability requirements. The height of the WCFZ of working face 117 was predicted using this model, and the predicted value was compared with values measured by optical fiber monitoring and simple hydrological observations. The height of the WCFZ measured by optical fiber was 184.8 m, the predicted value was 196.0 m, and the relative error of that prediction was 6.0%. The hydrologically observed value was 221.0 m, the predicted value for that location was 225.7 m, and the relative error was 2.1%. Thus, the NNBR model is capable of reliably predicting the height of the WCFZ and it appears that it can be used to compute the safe water control height above mechanized top coal caving mines in western China’s very thick Jurassic coal seams.

     

近距离煤层下行开采工作面复合导水裂隙带高度研究

为研究近距离煤层下行开采工作面复合导水裂隙带发育高度,以某矿下行开采工作面为研究背景,采用工程地质调查、理论计算、数值模拟等手段进行了研究,研究结果表明：上工作面开采后形成的导水裂隙带高度为27.9 m;当层间距小于下工作面垮落带高度时,下工作面开采过程中,上工作面开采所形成的导水裂隙带会二次发育,两工作面复合导水裂隙带高度为48.4 m,大于两工作面间岩层厚度+上工作面采高+上工作面导水裂隙带高度,下行开采两工作面复合裂采比值为12.1。     

煤层开采后覆岩导水裂隙带高度的模拟研究

某矿为安全开采煤炭资源,采用经验公式预计和计算机数值模拟方法,按规划设计开采煤层厚度分别研究了单独开采16#煤、17#煤后覆岩导水裂隙带高度,采用经验公式计算为36.1m和29.7 m;采用计算机模拟方法计算为37.1 m、26.9m。研究了按规划设计开采煤层厚度将16#煤、17#煤全采后覆岩导水裂隙带高度为41.7 m。     

缓倾斜矿层覆岩卸压带高度数值模拟研究

基于岩层应力、渗透率等相关关系,分析岩层应力-渗透率关系函数,引入系数βii并定义其为岩层渗透相关系数,构建以渗透相关系数为参变量的卸压带高度指数预测模型。研究表明,在一定范围内卸压带高度随工作面推进而增加,且增加量逐渐减小,卸压带高度有向某一定值靠近的趋势。     

双端堵水器法在采场覆岩裂隙带发育规律实测中的应用

煤层的开采会导致上覆岩层原有应力平衡状态被破坏,进而造成从顶板到地表不同程度的变形和破坏,因此研究采空区覆岩裂隙分布特征,对煤矿安全生产具有重要意义。文章针对李村矿1301首采工作面的地质条件,采用井下双端堵水器观测方法,分析了导水裂隙带高度,确定了李村矿3号煤层顶板覆岩采后形成的裂隙带高度范围,为煤矿安全生产提供了技术指导。     

陕北矿区煤层稳定性及环境治理技术研究

研究陕北矿区煤层稳定性及环境治理技术,为煤矿开采过程中地质因素导致的开采难度提供指导并改善陕北区域生态环境污染情况。以陕北榆林市某煤矿作为研究对象,针对该地区可采煤层使用定性评价方法评价该煤层的稳定性,为提升评价结果客观性,进一步使用定量评价方法分析煤层稳定性。分析结果显示煤层5和煤层3-2属于稳定性煤层,而煤层2属于较稳定煤层,开采前景良好。针对研究区域存在的水污染、生态污染、固体材料污染等情况,提出合理污水处理、生态种植、矸石处理等治理技术,合理治理该研究区域由于煤矿开采造成的环境污染问题。     

近水平煤层综放面导水裂缝带最大高度分析及其研究

在近水平煤层条件下,利用离散元模拟的方法,分析了综放采场上覆岩层的运动特征,根据覆岩位移及应力变化规律,确定了覆岩的导水裂缝带高度.通过现场实测验证表明,数值模拟所得的裂缝带高度与实测结果相吻合,说明利用数值模拟的方法确定综放面覆岩导水裂缝带高度是可行的.     

基于MATLAB多元非线性特厚煤层导水裂隙带高度预计

为解决特厚煤层待采工作面导水裂隙带运用现有规程条件难以计算的问题,依据导水裂隙带与各主要影响因素之间的关系,结合正交试验法,构建不同影响因素下的工作面组合方案,利用3DEC软件模拟分析各工作面开采后的最大导水裂隙带高度,将其计算结果运用MATLAB软件进行多元非线性回归拟合,得到特厚煤层综放工作面导水裂隙带高度的计算模型。以大平矿已采工作面导水裂隙带高度监测数据为例,研究结果表明:计算模型预计结果与实测结果的最大相对误差为6.47%,最小相对误差为0%,平均误差为2.93%,误差结果较小,计算模型可用于特厚煤层待采工作面导水裂隙带高度的预计。     

深部采煤工作面上覆岩层裂隙带发育高度研究

根据唐口煤矿深部采煤工作面地质及回采技术特点,建立了UDEC数值计算模型,对工作面覆岩的应力、位移、塑形变形区等参量展开了系统研究。模拟结果显示,在1307工作面回采影响下,导水裂缝发育高度达到48.1 m,冒落带高度为14.6 m。     

坚硬顶板煤层群开采导水断裂带发育高度模拟研究

采用FLAC~(3D)数值模拟软件建立了大同矿区煤层群开采的数值模型,模拟研究了煤层群开采时覆岩导水断裂带的发育过程,分析了3-5~#煤层导水断裂带发育高度与煤厚、工作面长度的关系。模拟结果显示:坚硬顶板下近距离煤层群下行开采,随采动次数增加覆岩导水断裂带高度增加的幅度逐渐减小;随煤层厚度的增加,3-5~#煤导水断裂带高度增加,当煤厚13 m时,其增幅变大;随工作面长度的增加,3-5#煤导水断裂带高度增加,当工作面长度190 m时,导水断裂带增幅减小;煤厚为15 m时,将工作面长度缩短至180 m时可确保3-5~#煤的导水断裂不与15#煤采空区贯通。     

煤层采后导水裂隙带探测方法探讨

导水裂隙带对煤矿防治水工作有着重要的意义。经验表明,行业内总结出的一些导水裂隙带通用计算公式并不适用于所有井工煤矿,因此导水裂隙带实测对于受煤层上部含水体威胁的煤矿具有重要的意义。文章在总结以往导水裂隙带探测的基础上,结合目前国内最新的导水裂隙带探测技术,以望云矿为例对煤层采后导水裂隙带井下实测方法进行了探讨,并设计出符合望云矿实际情况的导水裂隙带井下综合探测方法。     

大采高综采煤层塑性区计算分析

在大采高综采工作面中,塑性区宽度的确定是采取安全措施的理论依据。以某矿4.2 m厚煤层开采为现场研究条件,通过现场实测及理论分析,系统地研究了大采高综采煤体变形、破坏问题,准确地计算出煤体破坏塑性区的范围。     

高头窑煤矿2-3煤层“两带”高度观测及水体下安全开采技术

由于高头窑煤矿井田内水系较多且较发育,一旦在开采过程中工作面与地表水沟通,将会发生重大安全事故。为防止煤矿发生透水事故,采用经验公式法、类比法及数值模拟法,合理确定了防水安全煤岩柱尺寸。目前水多湖川下首个回采工作面正在安全开采,证明合理的煤岩柱留设及限厚开采达到了预期效果。     

雅店煤矿4号煤层开采导水裂隙带高度研究

为研究雅店煤矿4号煤层开采导水裂隙带发育高度,首先采用UDEC数值模拟方法分析了煤层开采后覆岩破坏规律、应力分布规律和导水裂隙带发育高度;其次采用理论计算方法和工程类比法确定4号煤层47个钻孔的导水裂隙带高度,并根据现场钻孔实测数据,对比得出导水裂隙带突破煤层上方洛河组含水层(K1l)的范围及深度;最后综合考虑数值模拟、理论计算、工程类比和现场实测结果,得出4号煤层导水裂隙带平均高度为205~214 m,最大裂采比为20。研究结果表明：4号煤层开采覆岩导水裂隙带大部分已突破洛河组含水层底界,矿井正常生产时应采取有效措施确保安全开采。     

深埋中厚煤层构造破碎带支护参数优化

针对山东某煤矿12213工作面,以掘进上轨道巷遇断层后顶板破碎为基础,对巷道的构造破碎带支护方式及支护参数进行了合理优化分析与研究。并通过FLAC3D模拟软件,对2种支护方式的支护效果进行了对比。对构造带巷道的支护方式及参数优化分析,选择了合理的支护方式及参数。     

水压力作用下煤层内控制孔对裂纹扩展影响

煤层卸压是有效降低煤层压力的措施,为了提高煤层卸压的效果,利用RFPA3D并行分析系统,应用有限元的计算方法,建立流固耦合模型。模拟分析了在有恒定水压力下4个方向的控制孔诱导裂纹扩展的过程,其结果表明由于最大主应力的作用,新萌生裂纹最终向着有恒定水压力的控制孔方向扩展,并且最终与控制孔贯通。这对煤层卸压起到了一定的增透作用。     

Prediction of the Height of the Water-Conducting Zone Above the Mined Panel in Solid Backfill Mining

Numerous water inrush disasters have been associated with Chinese coal mines over the past 30 years. Accordingly, solid backfill mining (SBM) has been widely adopted to extract coal resources from beneath aquifers to reduce the magnitude and scope of overburden failure. Therefore, accurate determination of the height of the water-conducting zone associated with SBM is particularly important. The primary factors influencing development of water-conducting zones within solid backfill mines have been quantified in the current study, based on overburden movement and deformation characteristics. Numerical simulation has been used to evaluate the height of water conducting zones with respect to mine heights and backfill ratios. The results have been analyzed via multiple regression, leading to the development of a predictive equation. Field trials undertaken as part of the current study indicate a high level of accuracy with the developed equation.     

保护层开采后周围煤岩体采动裂隙分布规律的研究

以沈煤集团红菱煤矿保护层开采为工程实例,通过开采11#煤层,对存在煤与瓦斯突出的7#煤层和12#煤层进行卸压,研究保护层开采后采动裂隙分布规律。阐述了含瓦斯煤的力学特性:通过相似模拟实验,用散斑法对保护层开采过程中采动裂隙分布规律及煤岩体的渗透性进行了分析。