Using of Key Stratum Theory to Study the Structural Development of Roof Aquifer

During the underground mining of coal resources,overlying rocks on the roof of excavated tunnels will be destroyed due to ground pressure,and as a result,part of them will break and fall into the tunnels.How to determine the distribution of fractured areas and fissures presents a major problem for preserving the overlying aquifer.

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 feld,thus ensured safely mining the very thick coal seam under water-rich roof.

Numerical research on stability control of roofs of water-rich roadway

In order to study the strength-weakening law of roofs of water-rich roadway, this study used FLAC software, and simulated and analyzed the failure characteristics of the surrounding rock of water-rich roadway under the condition of different cross sections and support parameters, finally obtained the stress distribution of the principle stress of the roadway as well as the displacement variation of its surrounding rock. Results indicate that the roof stability of roadway with semicircular cross section is better than the roadway with inclined rectangular cross section under water-rich condition. Besides, the surrounding rock deformation of roadway under the action of water shows a pronounced increase compared to the roadway without the action of water due to the fact that water will obviously weaken the surrounding rock of roadway, especially its roof. It is very beneficial to control roof stability of water-rich roadway and guarantee the roadway stability during its service life by improving the pretension of bolt and cable as well as decreasing inter-row spacing of the bolt.

Influence of confined water on the limit support pressure of tunnel face in weakly water-rich strata

In the process of shield tunneling through soft soil layers,the presence of confined water ahead poses a significant threat to the stability of the tunnel face.Therefore,it is crucial to consider the impact of confined water on the limit support pressure of the tunnel face.This study employed the finite element method(FEM)to analyze the limit support pressure of shield tunnel face instability within a pressurized water-containing layer.Subsequently,a multiple linear regression approach was applied to derive a concise solution formula for the limit support pressure,incorporating various influencing factors.The analysis yields the following conclusions:1)The influence of confined water on the instability mode of the tunnel face in soft soil layers makes the displacement response of the strata not significant when the face is unstable;2)The limit support pressure increases approximately linearly with the pressure head,shield tunnel diameter,and tunnel burial depth.And inversely proportional to the thickness of the impermeable layer,soil cohesion and internal friction angle;3)Through an engineering case study analysis,the results align well with those obtained from traditional theoretical methods,thereby validating the rationality of the equations proposed in this paper.Furthermore,the proposed equations overcome the limitation of traditional theoretical approaches considering the influence of changes in impermeable layer thickness.It can accurately depict the dynamic variation in the required limit support pressure to maintain the stability of the tunnel face during shield tunneling,thus better reflecting engineering reality.

Roof pre-blasting to prevent support crushing and water inrush accidents

Support crushing and water inrush when mining under an unconsolidated confined aquifer in the Qidong Coal Mine was prevented by roof pre-blasting. The mechanism and applicable conditions for this method have been studied. The results show that when an overburden structure that may cause support crushing and a water inrush accident exists the weakening of the primary key stratum, which thereby reduces its weighting step, roof pre-blasting is both feasible and effective. If the position of the primary key stratum can be moved upward to exceed 10 times the mining height the possibility of support crushing and water inrush disaster caused by key stratum compound breakage will be lowered. The overburden structure of the number 7121 working face was considered during the design of a technical proposal involving roof pre-blasting. After comprehensively analyzing the applicability of roof pre-blasting the resulting design prevented support crushing and water inrush disasters from happening at the number 7121 working face and laid a solid foundation for mining safely.

Stability control of water-enriched roofs of coal drifts

Excavation-and-support induced disturbances are likely to make water-enriched roofs to become weathered and fractured.The development and connection of cracks provide new water channels which may result in water loss,seriously affecting the in-tegrity and stability of roofs,leading to incidents of roof fall.Control of water-enriched rocks surrounding coal drifts is quite diffi-cult in China.Based on the practical situation of a water-enriched roof of a coal drift in working face 112201 of the Meihuajing coal mine,we studied the deformation features of surrounding rocks and the development of fractured areas and analyzed the major reasons for the decrease in load-carrying capacity,indicating that the key to maintain roof stability of this kind of coal drift is water retention.In addition,we proposed a staged control technology consisting of:1) surface grouting;2) cable anchor strengthening and 3) roof grouting,which has proven to be successful in this practical application.Our study indicates that,after the problem of water loss from the water-enriched roof had been effectively solved,a combined support system with high performance bolts can maintain the stability of the bearing structure,resulting in the control of roof stability in this kind of coal drift.

亭南煤矿巨厚砂岩含水层顶板灾害协同防控技术及应用

针对彬长矿区亭南煤矿主采煤层顶板为典型巨厚砂岩含水层结构,冲击地压、水害、瓦斯为主的多元动力灾害突出问题,基于此现场实测数据分析得到了亭南煤矿“冲击地压-水害、冲击地压-瓦斯”两类典型灾害链,通过室内试验研究了灾害链的致灾机理并制定了灾害协同防控原则,设计了包含采前、采中两阶段以及源头断链整体防控、系统防控隔离断链两种思路的巨厚砂岩含水层顶板灾害协同防控方法,并在亭南煤矿进行了现场应用。结果表明,随冲击幅值增加,动态损伤煤岩体的极限承载能力减小,冲击导致顶板损伤和弱化,沟通巨厚砂岩含水层;强冲击后砂岩试样孔隙率达8.23%,较未冲击增长了34.48%,冲击地压的发生使得岩体裂隙增加,为瓦斯逸散提供了通道;通过巨厚砂岩含水层顶板灾害协同防控技术,实测得到支架平均阻力为35.03 MPa,无明显应力激增现象,工作面涌水稳定于250~280 m^(3)/h,甲烷涌出量在0.2%水平波动。研究结果可为彬长矿区煤矿多元动力灾害防治提供支持,助力实现煤矿灾害风险高效防范,推动多元灾害协同防控技术进步。

“L型”疏放水系统构建及其在松散层防治水中的应用

矿井突水在矿井生产中始终是一个安全隐患,特别是对于顶板松散含水层,处理不当可能会发生溃水溃砂事故。为确保研究区薄基岩厚松散含水层下煤层的安全开采,采用疏降或疏干含水层水是一种有效方法,但井下疏放受松散含水层塌孔影响无法顺利实施。以赵家寨矿为例,通过“L型”顶板水疏放系统构建,将上覆新近系松散含水层水由顶板水转化为底板水,从井下巷道排出,解决了薄基岩厚松散含水层下煤层综放开采问题,实现了工作面的安全回采。该技术的成功应用,对类似水文地质条件下的煤层开采具有推广价值。

基于相关系数法的顶板含水层富水性主控因素分析

随着煤炭资源采掘深度的不断加大,矿井顶板水害问题日益严峻,准确评价煤层顶板充水含水层富水性对于煤矿防治水工作至关重要。含水层富水性是由具有不同相关程度的多元水文地质因素共同作用的结果,选取顶板含水层单位涌水量、渗透系数、砂岩厚度、冲洗液消耗量、岩芯采取率、脆塑性岩厚度比这6个主要控制因素,采用Pearson相关系数法对煤层顶板直接充水含水层富水性与各主控因素之间的相关性进行对比分析。通过评价各主控因素的正负相关性与相关程度,结合统计学方法计算Pearson相关系数进行相关程度的量化对比分析,为煤层顶板直接充水含水层的富水性评价提供依据。

纳林河二号矿井工作面顶板疏放水方案设计及优化

为了制定纳林河二号矿井工作面疏放水设计方案,保障矿井的安全回采,以3-1上201工作面顶板疏放水工程为例,通过绘制3-1上201工作面水文地质柱状概化图,分析了导水裂隙带发育高度及发育层位,确定了影响工作面安全回采的含水层为延安组三段砂岩含水层。根据物探异常区和“三图法”的富水性分区进行了顶板疏放水方案设计及动态优化,同时基于疏放水钻孔水量、水压变化,开展了疏放水效果评价,验证了基于“三图法”评价的疏放水方案设计的可靠性。

非稳定流含水层重构与顶板群孔泄水点判定研究

以石槽村煤矿宝塔山砂岩含水层为工程背景,构建了含水层三维可视化模型,通过单孔、多孔非稳定流模型对该可视化模型进行验证,并对顶板泄水点位置反演预估。结果表明:采区顶板群孔非稳定流模型数据与观测孔放水实测数据拟合性好,模型可信度高;含水层数值重构最优解为6个分区,即Ⅰ高渗中储水区、Ⅱ中渗高储水区、Ⅲ高渗高储水区、Ⅳ低渗中储水区、Ⅴ低渗低储水区、Ⅵ中渗中储水区;井下泄水点位置在G1-1观测点和F1-3观测点之间,泄水量为150~200 m 3/d。

复杂地质条件巷道探测钻孔施工及防治水技术研究

针对21106运输巷掘进区域内水文地质条件复杂的情况,提出采用长距离定向钻孔对顶板含水层进行超前疏排,从巷道掘进前即可降低顶板含水层富水量、水头压力,为掘进创造良好条件。为避免掘进期间围岩出现较大淋水问题,在巷道迎头布置2排探测钻孔,实现顶板及掘进前方一定范围内探测。现场应用后,21106运输巷顶板定向长钻累积疏排水量为1.69万m^(3)、迎头短距离探测钻孔疏排水量为3 690 m^(3),疏排后运输巷掘进期间围岩保持干燥,基本不出现淋水问题。

巨厚砂岩含水层下安全开采可行性研究

为研究巨厚砂岩含水层下工作面开采可行性,以陕西某矿5煤为研究对象,分析工作面水害程度与安全开采。研究结果表明:5煤工作面开采垮落带为22 m,垮采比为6.53;裂隙带最大发育高度为43.08 m,裂采比12.78,开采裂隙发育顶部处在直罗组直接含水层中下部。5煤煤系直接含水层,涌水量小且补给来源单一,径流滞缓;间接含水层因距离较远而难以形成导水通道。因此,工作面开采前,做好探放工作,可有效防止涌水事故。

基于EW-FAHP-GIS耦合的煤层顶板富水性评价

以薛虎沟煤矿10号煤层为研究对象,在分析煤层顶板富水性影响因素的基础上,运用熵权(EW)与模糊层次分析(FAHP)综合赋权法建立了顶板含水层富水性的脆弱性指数模型,基于地理信息系统(GIS)对煤层顶板含水层富水性进行评价。研究表明,10号煤层顶板含水层富水性的主控因素为含水层厚度、岩层脆塑性比、钻孔取芯率、钻孔漏失量和岩石质量指标,并建立了相应的脆弱性指数模型,据此进行K2含水层富水性评价,划分了富水性分区,为煤矿制定和实施合理的防治水规划提供科学依据。

煤层顶板含水层富水性评价及涌水量预测

为进一步探究煤矿煤层顶板含水层富水性及涌水量特征,为煤矿开采工作提供安全保障,以某煤矿开采过程中存在的涌水量较高问题为研究内容,综合应用AHP层次分析法与基于GIS的多源地学信息复合叠加的“富水性指数法”,对煤层顶板含水层富水性进行评价;应用“大井法”对涌水量进行预测,并证明该预测方法的准确性。结果表明,该预测方法具有一定的现实应用价值。

煤层顶板水综合治理技术研究

6503运输巷掘进工作面顶板上覆存在顶板砂岩含水层,巷道掘进期间容易出现涌水量大的问题,易引起顶板泥岩层失稳,增大围岩控制难度,影响巷道掘进效率。结合6503运输巷现场条件,提出综合采用超前定向长钻孔疏排+锚杆(索)全段锚注+围岩化学注浆+巷道围岩喷射WG防水剂及混凝土方式对顶板水进行综合治理。工程应用后,6503运输巷掘进期间围岩基本不淋水,巷道掘进基本不受顶板水影响,掘进速度保持在300 m/月以上,表明现场使用的顶板水综合治理技术效果良好。

红柳林煤矿中西部区域煤层顶板突水危险性评价

榆神矿区原煤产量持续增加,对推进国家西部能源基地建设,保障国家能源安全具有重要意义。随着煤层开采深度不断加大,地质环境条件越来越复杂,煤层顶板水害威胁日益凸显。依据红柳林煤矿中西部地区水文地质勘查成果资料,对煤矿水文地质条件和充水因素进行研究分析,拟评价煤层开采顶板突水危险性。研究表明,红柳林煤矿中西部区域煤层开采突水威胁主要来源于上覆含水层水与老空区积水,局部覆岩较薄地区随着导水裂隙带贯穿地表还受到地表水的影响。但总体而言,其突水程度受导水裂隙带发育高度影响,较为可控。提出的防治水工作建议可为矿井中西区煤层后续安全开采和顶板探放水工作提供科学依据。

梅花井煤矿232201工作面顶板水疏放效果评价研究

针对梅花井煤矿232201工作面面临的顶板砂岩水害问题,在工作面回采前开展了一系列防治水工作,通过探查顶板含水层并进行疏放水工程,对钻孔疏放水量进行观测。疏放水工程完成后,分析钻场水量的衰减率与稳定情况,结合工作面涌水量静储量和动态补给量预测值,对顶板水疏放效果进行了评价。结果表明:从钻孔、钻场水量变化来看,绝大多数钻孔衰减率达到100%,水量趋于稳定,顶板疏放水钻孔疏放水量大于静储量,疏放水效果良好。通过结合大井法预测的工作面涌水量以及钻孔疏放水的实际观测数据,对煤层顶部砂岩含水层的疏放水效果进行评价,该方法适用于类似工作面采前的水文地质条件评价中,对矿井的水害防治和水资源管理提供了重要的实践指导。

鄂尔多斯盆地北部典型顶板水害特征及其防治技术

为了查明鄂尔多斯盆地北部典型顶板水害的形成机理,并提出有针对性的防治措施,在系统分析区域含水层厚度、赋存特征、分布规律、水文地质参数等矿井水文地质条件的基础上,结合鄂尔多斯盆地北部诸多矿井顶板水害发生的特征,得出鄂尔多斯盆地西缘、东缘和北缘具有不同的顶板水害形成条件和特点,最具典型的水害类型分别为离层水害、薄基岩突水溃沙灾害和巨厚砂砾岩含水层顶板水害。研究了含水层沉积特征和水文地质结构,结合不同类型水害的形成要素和水害发生特征,初步查明了典型顶板水害的形成机理,"束状钻孔,靶向探放"是防治离层水害的有效方法,井上下疏放水和注浆改造是防治薄基岩突水溃沙的有效途径,顶板水超前疏放和加强排水系统是巨厚砂砾岩含水层顶板水害防治的主要方法。大量的工程实践资料验证了对水害条件认识的正确性和水害防治方法的有效性。

我国水体下保水采煤技术研究进展

针对我国水体下保水采煤的理论与实践,就采动覆岩导水裂隙演化规律,以及在此基础上形成的保水采煤技术研究进展进行了综述和展望。结果表明:导水裂隙作为地层含水层破坏与地下水漏失的主要根源,其动态发育与发展直接受控于覆岩关键层的破断运动;因而,可按具体开采条件下覆岩关键层的赋存情况进行导水裂隙带高度的确定,从而科学指导水体下保水采煤对策的制定。依据水体下保水采煤所包括的4个层次的内涵,分别从顶板突水灾害防治、含水层原位保护、采动破坏含水层的再恢复、采动漏失水资源的转移储存与利用等4个方面,进行了相关保水采煤技术研究进展的论述,在此基础上提出了今后的研究方向。