短壁开采的关键层变形与地表沉降耦合作用的数值分析

以潞安矿业集团五阳煤矿村庄下的短壁开采为背景,采用有限元数值模拟软件RFPA2D,对短壁开采中关键层变形与地表沉降情况进行了数值模拟.通过开采宽度和煤柱宽度两个参量的有机组合,研究了地表变形和关键层变形的耦合关系,结果表明,地表变形是受关键层变形约束的,关键层破断前,地表下沉量随关键层下沉量增加而增加,关键层破断后,上覆岩层整体下沉,地表下沉量发生突变,煤柱破坏不仅与自身的宽度有关,也与开采宽度有关。     

充填开采引起地表沉陷的影响因素探讨

针对煤矿膏体充填开采，就其引起的地表沉陷影响因素进行探讨，通过数值模拟和实践分析总结出影响因素可从三个方面考虑，即下沉量因素、压缩量因素和岩性因素。其中充填前顶板下沉量、充填体欠接顶量和充填体压缩量是三个主要影响因素，此外，特定地质条件下应考虑关键层和厚表土层的影响因素。     

采高

采煤机的实际开采高度称为采高。采高的概念不同于煤层厚度。分层开采厚度煤层,或有顶煤冒落,或有底煤残留时,煤层厚度就大于采高;反之,在薄煤层中,由于截割顶板或底板,采高也可能大于煤层厚度。 考虑煤层厚度变化、顶板下沉和浮煤等会使工作面高度缩小,因此煤层厚度不宜超过采煤机最大采高的90％～95％;不宜小于采煤机最小采高的110％～120％。采高对确定采煤机整体结构有决定性影响,它既规定了采煤机适用的煤层厚度,也是与支护设备配套的一种重要参数。     

采高

<正>采煤机的实际开采高度称为采高。采高的概念不同于煤层厚度。分层开采厚度煤层,或有顶煤冒落,或有底煤残留时,煤层厚度就大于采高;反之,在薄煤层中,由于截割顶板或底板,采高也可能大于煤层厚度。考虑煤层厚度变化、顶板下沉和浮煤等会使工作面高度缩小,因此煤层厚度不宜超过采煤机最大采高的90%~95%;不宜小于采煤机最小采高的110%~120%。采高对确定采煤机整体结构有决定性影响,它     

煤层厚度

煤层顶、底板岩石之间的垂直距离称煤层厚度。从勘探和开采角度把煤层厚度分为：a）煤层总厚度,指包括夹石层在内的煤层全部厚度;b）煤层纯煤厚度,指所有煤分层厚度的总和;c）煤层可采厚度,指在现代经济技术条件下适于开采的煤分层的总厚度。按照国家有关技术政策,根据煤种、产状、开采方式和地区煤炭资源供需情况,及地理条件规定的可采厚度下限,称最低可采厚度。达到可采厚度的煤层称可采煤层。     

辽河油田稠油蒸汽驱注采井射孔方式

针对辽河油田蒸汽驱出现的蒸汽超覆和高渗层过早蒸汽突破现象,分析了各射孔方式的优势和不足,应用数值模拟方法,进行了不同厚度油层射孔方式研究,提出了新的注采井射孔方式。新的方式强调厚油层避射顶部,具体避射比例因厚度不同而定;注汽井按油层渗透率级差确定射孔密度,对与生产井油层连通的差油层适当加密射孔;井组内其他生产井中与注汽井射孔层连通的差油层也相应实施加密射孔。     

应用长胶筒封隔器保护隔层定位压裂开采厚油层内剩余油

喇嘛甸油田厚油层内具有发育薄结构界面的特点,目前已进入高含水开发后期,为了控制压裂后含水上升,改善压裂效果,针对厚油层常规压裂无法确定裂缝开启位置的问题,提出应用长胶筒封隔器保护隔层定位压裂开采厚油层内剩余油。通过裂缝形态分析和层内细分隔层界限研究,确定了在隔层厚度小于0.8m的条件下应用胶筒长度为1.0m和2.0m的封隔器实施保护隔层压裂工艺,对厚油层内进一步细分压裂,达到定位压裂开采厚油层内中低含水部位剩余油的目的。长胶筒封隔器在保护隔层压裂工艺方面累计实施249口采油井,平均夹层厚度为0.2m,措施后累计增油19.4×10~4t,投入产出比达到1∶11.1;利用2.0m长胶筒封隔器封堵厚油层底部高水淹部位,再通过工艺控制实现在厚油层内中上部低含水部位的强制压裂造缝的现场应用试验正在开展,效果有待进一步评价。     

薄煤层工作面切顶卸压留巷技术研究

为提高矿井煤炭资源回收率并提高煤炭开采效率,结合3503综采工作面开采煤层厚度薄的特点,针对性提出切顶卸压留巷技术方案,并进行工程应用。在回风巷切顶卸压留巷期间,通过锚索超前补强可提高留巷段顶板强度,为留巷工作开展创造良好条件;使用DCA-45型切缝机提高切顶钻孔施工质量,通过聚能爆破方式提高切缝效果;在滞后支护段采用密集单体进行补强,可减少采动压力、采空区顶板垮落等对留巷段围岩变形影响。现场应用后,留巷段顶板在滞后采面30 m范围内下沉量增加速度较快,随着与采面距离增加留巷段下沉量逐渐趋稳,最终下沉量控制在165 mm以内。     

南通城区地质灾害类型与特征研究

南通城区大部属长三角冲积平原,浅部软弱土层发育,松散层覆盖较厚,人类工程活动引发的地质灾害主要有地面沉降和特殊类岩土（砂土、软土）灾害。狼山地区属基岩残丘区,主要发育有崩塌和滑坡2种突发性地质灾害。该文阐述了南通城区发育的地面沉降、崩塌、滑坡和特殊类岩土（软土、砂土）地质灾害的类型和分布特征,分析了南通城区各种地质灾害的形成机理、成因特征及危害性,并结合灾害地质环境条件提出了相应的防治措施。     

西北干旱-半干旱区大水煤矿充水条件及涌水量特征——以锦界煤矿为例

在收集锦界煤矿水文地质特征的基础上,对矿井涌水量组成与变化影响因素进行分析。结果表明:开采充水强度主要取决于风化带和潜水含水层的富水性、导水裂缝带发育程度、煤层上覆基岩厚度与采动后隔水层的隔水性能;工作面涌水量与推进距离与采空区面积呈正相关,停采线附近涌水量普遍上升。     

综采放顶煤技术研究与应用

论述了综放开采与厚煤层倾斜分层开采相比而言具有的优越性及其使用条件和采场矿压显现的规律,总结了几点关于综放开采覆岩破坏和地表沉陷规律。     

蛤蟆沟煤矿30104工作面地表岩移及变形规律分析

以蛤蟆沟煤矿30104工作面综采上覆岩层移动及地表沉陷规律为对象开展研究,从位移观测站建立、地表沉陷规律分析、地表变形动态分析、数值模拟等多个方面,对综采作业引起的覆岩移动和地表沉陷做出全面分析,为指导地面工业广场下方留设合理保安煤柱提供依据。     

综放开采下覆岩移动和地表沉陷规律探究

以综放开采下覆岩移动及地表沉陷规律为对象开展探究,结合具体工程实际,从位移观测站建立、地表沉陷规律分析、地表变形动态分析等多个方面对综放开采作业引起的覆岩移动和地表沉陷做出全面分析,希望能够为其他矿井相似工程的开展提供借鉴与参考。     

采煤塌陷区矿山地质环境治理模式探析

在中国当前的矿山地质环境治理过程中,采煤塌陷区地质灾害处理始终是一个难点。针对矿山采煤塌陷区的具体形成条件、发育特征以及具体的表现形式进行深入分析,并就矿山采煤塌陷区矿山地质环境的治理进行总结归纳,希望能够为后期进行采煤塌陷区矿山地质环境治理起到科学的指导作用。     

浅谈煤矿井下厚煤层开采的工艺选择

厚煤层是中国煤矿开采的主要对象,实现厚煤层的安全高效开采具有重要意义。为了实现厚煤层的高效开采,需要选择合适的开采工艺。简要阐述了厚煤层开采工艺的选择原则,并重点分析了分层开采工艺、大采高一次采全厚工艺和放顶煤开采工艺的优缺点,以期为不同情况下厚煤层开采工艺的选择提供参考。     

采煤沉陷区水系与集水区变化预测分析

煤炭开采导致地表沉陷,形成局部洼地,进而改变流经水系的结构及其汇水范围,对此进行预测非常必要,为此将现状年(2010年)的地形与规划年(2030年)的预测沉陷值进行叠加,形成规划年的预测地形,基于此地形利用ArcSWAT提取规划年的水系和集水区,并通过与现状年的水系和集水区进行对比,分析地表沉陷动态发展条件下沉陷区洼地对天然湖泊、水系和洼地集水区变化的影响。结果表明,地表大幅沉陷会造成河道逆流和断流、不同水系连通、集水区兼并等重大水文、地理格局变动。     

Numerical modeling and experimental study of the influence of GDL properties on performance in a PEMFC

This work is to study the effect of properties of gas diffusion layer (GDL) on performance in a polymer electrolyte membrane fuel cell (PEMFC) by both numerical simulation and experiments. The 1-dimension numerical simulation using the mixture-phase model is developed to calculate polarization curve. We are able to estimate optimum GDL properties for cell performance from numerical simulation results. Various GDLs which have different properties are prepared to verify accuracy of the simulation results. The contact angle and gas permeability of GDLs are controlled by polytetrafluoroethylene (PTFE) content in micro-porous layers (MPLs). MPL slurry is prepared by homogeneous blending of carbon powder, PTFE suspension, isopropyl alcohol and glycerol. Then the slurry is coated on gas diffusion mediums (GDMs) surface with controlled thickness by blade coating method. Non-woven carbon papers which have different thicknesses of 200 μm and 380 μm are used as GDMs. The prepared GDLs are measured by surface morphology, contact angle, gas permeability and through-plane electrical resistance. Moreover, the GDLs are tested in a 25 cm² single cell at 70 °C in humidified H₂/air condition. The contact angle of GDL increases with increasing PTFE content in MPL. However, the gas permeability and through-plane electrical conductivity decrease with increasing PTFE content and thickness of GDM. These changes in properties of GDL greatly influence the cell performance. As a result, the best performance is obtained by GDL consists of 200 μm thick non-woven carbon paper as GDM and MPL contained 20 wt.% PTFE content.     

In situ measurement using FBGs of process‐induced strains during curing of thick glass/epoxy laminate plate: experimental results and numerical modelling

For large composite structures, such as wind turbine blades, thick laminates are required to withstand large in‐service loads. During the manufacture of thick laminates, one of the challenges met is avoiding process‐induced shape distortions and residual stresses. In this paper, embedded fibre Bragg grating sensors are used to monitor process‐induced strains during vacuum infusion of a thick glass/epoxy laminate. The measured strains are compared with predictions from a cure hardening instantaneous linear elastic (CHILE) thermomechanical numerical model where different mechanical boundary conditions are employed. The accuracy of the CHILE model in predicting process‐induced internal strains, in what is essentially a viscoelastic boundary value problem, is investigated. A parametric study is furthermore performed to reveal the effect of increasing the laminate thickness. The numerical model predicts the experimental transverse strains well when a tied boundary condition at the tool/part interface is used and the tool thermal expansion is taken into account. However, the CHILE approach is shown to overestimate residual strains after demoulding because of the shortcomings of the model in considering viscoelastic effects. The process‐induced strain magnitude furthermore increases when the laminate thickness was increased, owing mainly to a decrease in through‐thickness internal transverse stresses. Copyright © 2012 John Wiley & Sons, Ltd.     

坝基混凝土防渗墙应力变形三维有限元分析

为研究不同连接型式下基岩强度对混凝土防渗墙应力变形的影响,结合巴拉水电站土石坝混凝土防渗墙对坝体和防渗墙的应力变形进行二维和三维有限元方法计算,揭示了防渗墙应力变形随主要影响因素变化的规律,并分析了不同连接型式、不同强度的基岩对混凝土防渗墙墙体变形和应力的影响。结果表明,对防渗墙进行数值模拟时,设置有厚度节理单元可较好地模拟墙体两侧的"泥皮",结果较合理;基岩强度较高时,防渗墙和基础的连接方式对防渗墙应力变形的结果影响较大;进行三维模拟能更准确地反映防渗墙的应力变形特征。     

Heat transfer over a bidirectional stretching sheet with variable thermal conditions

The heat transfer characteristics of a steady three-dimensional viscous fluid flow driven by the bidirectional stretching of an elastic surface are investigated. The hydrodynamic part of the problem is determined by the ratio between the stretching rates in the two lateral directions. The prescribed temperature or heat transfer rate varies along the surface. A heat source is included in the thermal boundary layer equation, which transforms into an ordinary differential equation by means of a similarity transformation. The numerical results show that the principal effect of the variable surface conditions is to thicken the thermal boundary layer when the temperature or heat transfer rate decreases with the distance from the center of sheet. The boundary layer thickness is correspondingly reduced if the sheet temperature or heat transfer rate increases in one or both of the lateral directions.