山脚树矿1.8Mta新井设计【含CAD图纸+文档】
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沿空掘巷技术研究摘要:本文以现场观测为基础,略述无煤柱护巷方法之一沿空掘巷,分析沿空掘巷的基本依据,探索沿空掘巷护矿压显现规律及其特征,进而提出沿空掘巷的维护措施。关键词:沿空掘巷,窄煤柱,围岩应力分布,支护工艺0 引言在煤矿地下开采中,在相当长的时期内,为了防止采动支承压力的有害影响,采准巷道一直采用煤柱护巷的方法。这些护巷煤柱一般不能回收。回采空间侧向支承压力的影响范围是确定护巷煤柱尺寸的主要依据。从世界各国的矿压观测资料来看,回采引起的支承压力分布范围很广,其影响区域主要与开采深度和煤岩性质有关。当深度为100200米时,应留1020米的煤柱;当深度为500600米、围岩强度为400公斤/厘米时,则应留3050米的煤柱,但在同样深度的条件下,倘若围岩强度只有200公斤/厘米时,那么取80100米宽的煤柱也不能确保巷道的良好状态;当深度为1000米、围岩强度为400公斤/厘米时,必须留大于90米的煤柱。矿压观测结果说明,随着开采深度的增加,护巷煤柱的尺寸变得越来越大。其结果,不仅使煤炭损失过大,千吨准备煤量的巷道掘进长度增加,而且残留的护巷煤柱在较大深度的煤层中,还会导致岩层压力增加,使煤和瓦斯突出以及冲击地压发生的危险性增大,煤柱下近距煤层的采掘工作条件恶化。上述情况极其尖锐地向采矿工作者提出:必须寻求和施行一种新的无煤柱护巷方法。经过众多国内外学者研究,最终提出无煤柱护巷方法沿空掘巷。沿空掘巷就是沿已稳定的采空区边缘或与采空区之间留小煤柱布置巷道, 在该巷道掘进时,相邻采空区岩层活动相对已经停止,其回采期引起的应力重新分布也趋于稳定,此时,沿空掘进的巷道处于应力降低区,有利于巷道维护。1 沿空掘巷技术在我国的发展分为以下几个阶段20世纪50年代我国已有个别矿井自发地应用沿空掘巷技术,可以说是沿空掘巷技术在我国发展的萌芽阶段。20世纪70年代沿空掘巷技术有所发展,并开始矿压研究,取得了可喜的成果,这个阶段是沿空掘巷技术的发展阶段。20世纪80年代初期提出了沿空掘巷巷道围岩变形特征,这个时期是沿空掘巷技术的完善阶段。20世纪90年代随着锚杆支护的大面积应用推广,极大促进了沿空掘巷技术的发展,这就是沿空掘巷技术的成熟阶段了。我国煤矿巷道布置在20世纪70年代以前主要是学习借鉴前苏联的经验,曾主要采用双巷布置留煤柱护巷系统。但由于当时的巷道支护技术落后,留煤柱护巷困难;厚煤层分层开采或近距离煤层群联合开采时,区段煤柱的留设造成的应力集中,不利于下分层或下层煤的开采;厚煤层分层开采时,区段煤柱的留设易于引起煤层自然发火煤巷采用炮掘法施工,掘进速度慢,双巷布置时准备时间较长。因此,自20世纪70年代后期,我国开始试验推广跨上山沿空掘巷(或沿空留巷)技术。目前,在厚及特厚煤层分层开采中仍主要采用这种布置系统,包括充州矿区在内的许多采用综采放顶煤开采技术的矿区也主要沿用了这种系统。与此同时,许多科研单位和学院研究单位也对这些问题进行了大量的实验室相似模拟和现场的观测,将理论和实践想结合起来,使得这些问题得到了进一步的发展。但是,在厚及特厚煤层一次采全高的综放开采系统中,煤柱护巷双巷掘进系统的原有缺点有的已不存在,有的己具备了解决的技术条件,而跨上山沿空掘巷系统岩巷多、邻面接续难等缺点在综放开采中却逐渐突出出来。实现无岩巷多煤巷布置的前提条件,是要有先进的煤巷支护技术,并能实现煤巷机械化的快速掘进。我国有很多矿都有这些技术,如兴隆庄煤矿煤巷新型高强锚杆支护己取得成功、煤巷综合掘进机械化施工速度己达100米/月以上,均己达到国际先进水平,完全具备了无岩巷多煤巷布置的技术与施工要求自80年代初试验综合机械化放顶煤开采以来,我国技术水平已处于国际领先地位,初步解决了储量和产量占我国 的厚煤层开采问题。1998 年以来年产超200万吨的综采队中的约80% 采用放顶煤,历年超300万吨、400万吨的全国综采纪录也为综采队所创 由此可见,综放开采已经成为我国高产高效矿井建设的主要技术手段之一。 但是由于综放工艺的限制,目前综放采区采出率还比较底,据统计,在综放采区的煤炭损失中,工作面区段煤柱损失约占8.9% ,仅次于工作面顶煤损失而位居第二,因而实现综放开采区无煤柱开采和最大限度减少“ 两巷” 煤损量,对提高采区采出率具有重要意义。2 沿空掘巷的理论概述2.1沿空掘巷巷道布置方式2.11紧贴采空区的沿空掘巷该布置方式可适用于走向长壁或倾斜长壁后退式采煤法,由于紧贴采空区掘进,部分地段可见采空区矸石,沿空掘巷期间巷道压力不大,整个巷道无明显变形,回采期间由于采动压力影响和其它原因支架变形较大,但基本能保证正常生产。2.12留小煤柱的沿空掘巷沿空掘巷时,为了防止从采空区向巷道窜矸或采空区积水和有害气体进入巷道,在巷道与采空区之间留13m小煤柱,掘进过程中无明显压力,局部地段可能有采空区渗水,但不影响施工,工作面采动影响期间影响不严重,可能在风巷靠近采空侧出现部分底鼓、挤帮现象。回采期间除进行超前支护外,不需要进行大的维修。以上两种沿空掘巷方式,当区段按顺序接续开采时,难以避免下区段的掘进受上区段回采的影响,为了克服此缺点,可以采用跳采的方式。2.13留临时大煤柱沿空掘巷在要求上、下区段按连续顺序接替回采,采区的条件又不适于应用间隔开采沿空掘巷时,为了避免下区段掘进工作受上区段采动影响,可采用留临时大煤柱的沿空掘巷方式。这种方案的实质是在掘进下区段的风巷时用尺寸较大的煤柱与上区段采空区隔离,以免巷道掘进受到上区段影响。本区段回采时又从采空区边界沿上区段采空区边缘与采面推进方向同向掘一条回风小平巷,以便回收临时大煤柱时构成通风回路。该小平巷超前距离只要稍大于联络眼的间距,并可随采随废。采用这种方式后不仅巷道压力小,维护条件大为改善, 甚至可无须维护,几年内就减少煤炭损失达上百万t。2.14厚煤层沿空掘巷厚煤层沿空掘巷的原理与中厚煤层相同,但由于厚煤层常进行分层开采,加上厚煤层开采对防火防沼气往往有更高的要求,所以其巷道布置一般较薄及中厚煤层复杂。2.2沿空掘巷的优点(1) 巷道在煤体边缘的应力降低区内掘进,巷道压力小,有利于巷道维护。(2)煤体边缘经受过支承压力的破坏作用后,瓦斯得到自然释放,对有冲击地压和瓦斯突出的煤层可以大大减少其危险性,有利于保证巷道掘进的安全。(3)与留煤柱护巷相比,可提高煤炭的采出率。(4) 与沿空留巷相比,可缩短巷道的维护时间,减少维护费用。(5) 由于没有留设护巷煤柱,改善了下覆煤(岩)层的地应力状态,即在下覆煤(岩)层中不再形成应力集中区,或应力集中区的范围较小,强度降低。2.3沿空掘巷的缺点(1)沿空掘巷与老采空区相通或留设很窄的煤柱,会造成巷道和采空区之间的漏风,不利于巷道通风。(2) 完全沿空掘巷和保留老巷部分断面的沿空掘巷,由于巷道一侧为采空区,上区段的老空区积水和碎研石易进人巷道内,严重影响巷道的施工和使用。(3) 由于沿空掘巷需在上区段回采完毕,等待采空区上覆岩层移动基本稳定后可开始掘进,不利于同一区域同时布置采掘平行作业。2.4沿空掘巷方式的选择综上所述,考虑到企业减少煤炭损失、提高煤炭采出率的要求,沿空掘巷主要分为完全沿空掘巷和留设小煤柱沿空掘巷。前者更易于维护,煤炭回收率高,适于老空积水少、老顶矿石破碎、低瓦斯的矿井。有的矿地质条件复杂、断层纵横交错、上区段老空积水较多,故选用留设小煤柱沿空掘巷。煤柱留设主要防止老空积水有害气体及大块岩石窜入巷道内,在上述前提下,留设煤柱越小越好,特别是沿空掘巷需要做进尺巷时,留设小煤柱则更有必要。留设窄小煤柱沿空掘巷技术是提高煤炭回收率的有效途径之一。 3沿空掘巷围岩活动规律3.1沿空掘巷顶板破断规律上区段工作面回采结束后,采空区上覆岩层垮落,老顶在采空区边缘发生断裂,形成“O-X”破断工作面不断向前推进,老顶周期破断,在工作面端头破断,形成弧形三角块( 如图3-1所示) 直接顶岩层跨落后,老顶弯曲下沉向采空区倾斜,沿工作面倾向,岩体A、岩块B、岩块C、组成铰接结构。岩块B对沿空巷道上覆岩层结构的稳定起重要作用,块体的回转变形对下方巷道围岩具有重要影响。图3-1 采区上覆岩层结构示意3.2沿空掘巷矿压显现规律3.21煤体斜方向支承压力分布规律分析倾通过我国大量矿压观测和有关研究表明,沿煤层倾斜方向的支承压力一般分布形式( 见图3-2) 。图3-2 支承压力一般分布形式图Lu煤体边缘低压区;ab强烈显现区;Lmax峰值位置;L影响总范围根据统计资料表明,沿倾斜支承压力显现的有关参数变化很大,L0=16m时,Lmax= 420m,而L= 1040m。研究表明,支承压力峰值距煤体边缘的距离( 即塑性区宽度) Lmax与煤层坚固性系数、顶板单向抗压强度Rc、煤层采高M、煤层倾角、采深H等因素有关,可根据实测资料得到回归公式进行近似计算。采区煤层巷道沿倾斜方向的矿压显现规律:从煤体边缘向矿体深部可分为三个不同的矿压显现带,即煤体边缘卸载带、支承压力显现带和原岩应力带。(1)煤体边缘卸载带:在高应力作用下,矿体边缘会产生变形和破坏,使其承载能力降低,从而形成较原岩应力低的卸载带。(2)支承压力显现带:由于边缘煤体遭到破坏后已基本上失去承载能力,上覆岩重即向煤体深部转移,从而形成沿倾斜方向的支承压力影响带。(3)原岩应力带:随远离煤体边缘,支承压力影响逐渐减弱,至煤体内部一定距离处即转入原岩应力状态,称原岩应力带。众所周知,地下岩体时应力不仅受士覆岩层的压力作用而产生,而且还要受各种地质作用和残余应力的强烈影响。工作面开采后,在工作面前方由于支承压力的作用,始终存在着一个高应力区。这个高应力区随着工作面的推进而向前移动,称为超前移动支承压力区。在邻近工作面两侧的煤体上也同样存在着支承压力。侧向支承压力在把两侧煤体的边缘部份压酥破坏后,又会向煤体的深处移动。随着工作面的远离和时间的推移,侧向支承压力会逐渐地稳定下来,较长时间地作用在两侧煤体上,形成一个高应力区,称为残余支承压力区。3.22沿空掘巷的围岩力学环境沿空掘巷的围岩力学环境与其它类型的回采巷道相比,一般具有以下三个显著的特点:(1)巷道处于应力降低区;(2)掘巷期内围岩应力集中程度小;(3)回采期间应力集中程度很大4 沿空掘巷窄煤柱设计概论4.1留窄煤柱沿空掘巷的理论依据由留窄煤柱沿空掘巷应力分布可知,煤、岩性质和窄煤柱宽度的不同,垂直应力的高峰值也不同,当窄煤柱确定不合理时,有可能使新掘的巷道处于原支撑压力高峰之下,原来的松驰区为窄煤柱宽度,而布置的掘进巷道则靠近极限平衡区,当巷道掘进以后,煤体强度急剧下降,窄煤柱进一步遭到破坏而卸载,引起煤柱向巷道方向强烈位移,巷道的另一侧煤柱,掘巷之前为承受高压的弹性区,掘巷之后,随着松弛区、塑性区的重新构成和支承压力向煤柱深部转移,与此同时伴随着顶板强烈下沉和底鼓。因此合理选择窄煤柱的宽度是沿空掘巷的关键一环,若煤柱尺寸选择不当,就会造成适得其反的效果。4.2留窄煤柱沿空掘巷的技术关键(1)留窄煤柱沿空掘巷必须有一个合理的滞后时间,即只有在采空区岩层运动已经稳定的前提下,才能取得较好的效果。因为采空区岩层运动已经稳定是沿空掘巷的受力和维护状态比沿空留巷要优越的先决条件,若沿尚未稳定的采空区一侧掘进巷道,无论是否留煤柱,它们的维护状态都比已稳定的采空区一侧掘巷要困难的多,如滞后回采工作面较短,就不能保证沿空掘巷的成功。根据采空区的冒落应力分布情况及以往经验,工作面合理的滞后时间为3 5个月。(2)必须正确确定合理的窄煤柱宽度。选择合理的窄煤柱宽度是能否取得沿空掘巷成功的关键一环,从理论上讲,完全沿空掘巷最为有利,但在实际中,为了防止漏风和采空区落矸,一般均采用留窄煤柱沿空掘巷。根据极限平衡区宽度计算公式及采空区的应力分布情况,确定了窄煤柱宽度在6 8m最为适宜,这样既能保证巷道布置在卸载区内,又能防止采空区瓦斯和水的涌入,保证安全生产。(3)必须有合理的支护形式和支护参数。沿空掘巷合理的支护应为锚杆支护,在锚杆支护设计上应遵守以下原则: 第一,顶板采用锚、网、钢支护,使巷道围岩和锚杆支护体系形成一个整体,从而提高巷道围岩的稳定性;第二,顶部两帮要比顶部锚杆加长200mm,以使顶板的部分载荷转移到巷帮煤体上;第三,两帮锚杆采用有预应力的锚杆,以便及时对煤帮产生挤压和加固作用。4.3窄煤柱合理宽度设计4.31窄煤柱设计原则(1)锚杆的安设基础;(2)相对有利的应力环境;(3)保证锚杆具有良好锚固性能;(4)巷道围岩变形的原则;(5)煤损小。4.32窄煤柱宽度计算合理窄煤柱宽度的确定可以从理论计算、数值分析、工程实践三个方面综合考虑。下面以中等稳定围岩条件举例说明。(1) 理论计算法如果煤柱过窄,则开巷后煤柱易于迅速变形破裂而使锚杆安设在破碎围岩中,使锚固力减弱、锚杆的支护作用降低。通过极限平衡理论研究认为,合理的最小煤柱宽度B为:B= x1+ x2 + x3 ( 1)式中: x1-因上区段工作面开采而在下区段沿空掘巷窄煤柱中产生的破碎区,其宽度按式(2) 计算。式中:x2-巷道窄煤柱一帮锚杆有效长度,再增加15%的富裕系数,m;x3-考虑煤层厚度较大而增加的煤柱稳定性系数,按0.2( x1+x2 ) 计算;m-上下区段平巷高度,m;A-侧压系数,A=(1-);(2) 数值模拟分析法数值模拟的优势在于能考虑众多的影响因素,并通过对比分析而得到一个较优的结果。利用FLAC3.3对中等稳定条件下不同窄煤柱( 1 6m) 宽度时,巷道围岩变形量进行了分析,计算中分别取窄煤柱宽度为2.5m、3m、3.5m、4m、4.5m、5m、5.5m及6m八个方案,对巷道在掘进及其本工作面回采期间的实体煤帮、窄煤柱帮、顶板下沉和底臌量进行了研究,得到以下结果:(a)不同煤柱宽度在掘巷期间的位移量(b)不同煤柱宽度在采动影响时的位移量图4-1 不同煤柱宽度在掘巷期间和在采动影响的位移量图其中图4-1( a) 、( b) 分别为沿空掘巷在巷道掘进期间和受本工作面采动影响时,窄煤柱宽度不同时实体煤帮、窄煤柱帮、顶板及底臌的变化趋势。由图4-1 ( a) 可见,沿空掘巷在巷道掘进期间,当窄煤柱的宽度不同时,巷道的围岩变形具有以下一些特点:窄煤柱宽度不同时,巷道两帮的围岩移近量均大于顶板的相对下沉量,说明在此期间,巷道的变形以两帮移近为主。在巷道的两帮移近量中,实体煤帮的移近量和窄煤柱帮的移近量虽稍有变化,但其量值相差不大。实体煤帮的变化趋势是随着窄煤柱宽度的增加,移近量稍有下降,但当煤柱宽度大于4.5m时,移近量又开始有一定的回升;窄煤柱帮的变形则随着煤柱宽度的增加变形量呈上升的趋势,但在一定煤柱宽度时,其变化趋势与实体煤帮逐渐趋于一致。在窄煤柱范围内,巷道的顶底板移近量以顶板下沉为主,底臌则相对要小一些。底板臌起量随着煤柱宽度的增加而开始增加,在窄煤柱范围内,其增加幅度较小;顶板的下沉量在巷道掘进期间是顶底移近量中的主体,但随着窄煤柱宽度的增加,顶板的下沉量逐渐呈下降的趋势。由图4-1 ( b) 可见,巷道受本工作面回采影响,窄煤柱宽度不同时,巷道围岩的变形具有以下一些特点:巷道在受采动影响时,巷道两帮的移近量也大于顶底板的相对下沉量,说明在本工作面回采时,巷道围岩的变形与掘巷期间类似,也是以两帮的变形为主。在窄煤柱条件下,巷道顶底板的移近量与煤柱的宽度有较大的关系,当煤柱宽度较小时,巷道的顶板下沉量要大于底板的臌起量;随着煤柱宽度的增加,底板的臌起量增加,而顶板的下沉量降低,底臌量大于顶板下沉量;当窄煤柱宽度达到6m左右时,两者的变形量逐渐趋于一致。在巷道两帮移近量中,实体煤帮的变形趋势与顶板下沉的趋势很相似,但其量值要大得多;窄煤柱的变形趋势则与底臌的变形趋势一致,但也是在量值上要大一些。同时还应注意到,窄煤柱宽度在一定范围内时,煤柱的变形要比实体煤帮的变形量大,最终随着煤柱宽度的增大,两帮的移近量均有不同程度的上升。通过上面的分析可以得出这样的结论:在窄煤柱条件下,沿空掘巷在巷道掘进期间,由于围岩的变形量普遍较小,窄煤柱宽度对巷道围岩变形量的影响不是很明显;但巷道在受本工作面的采动影响时,巷道围岩的变形量均较大,在此情况下,合理的窄煤柱宽度与巷道的稳定性有很大的关系。在中等稳定的围岩条件下,窄煤柱宽度在3.0m或5m左右较为合适。(3) 工程实践分析法沿空掘巷的窄煤柱设计具有很强的工程特征,故合理的窄煤柱宽度还应考虑工程中的一些要求:锚杆的安设基础。窄煤柱采用锚杆支护时,煤柱的宽度至少应大于锚杆的长度。现有条件下,锚杆一般长度多在2m左右,考虑到保留一定的宽度富裕系数,故要求窄煤柱的宽度应不小于2.5m。锚杆安设的可操作性。在留设窄煤柱条件下,锚杆支护中常会出现这样的问题,当窄煤柱破坏较为严重时,锚杆钻孔在凿出后会出现塌孔现象,致使锚杆的安装无法正常进行,故在实践中应予以考虑。(4) 窄煤柱的最终确定由以上研究可见,沿空掘巷采用锚杆支护时,窄煤柱的确定应充分考虑以下三个问题:其一,对沿空掘巷的窄煤柱来说,靠上区段工作面采空侧煤体中存在一定范围的破碎区,当在巷道侧窄煤柱中安设锚杆时,其宽度最好应能使锚杆位于采空侧所形成的破碎区之外,这样锚杆作用在较为稳定的煤体中,可以保证锚杆可靠的锚固能力。其二,沿空掘巷的窄煤柱尺寸决定了巷道与上区段工作面回采空间的距离,从而决定了巷道受侧向支承压力的影响程度;同时,窄煤柱的尺寸也将直接关系到窄煤柱自身的承载能力。其三,窄煤柱的宽度应能保证锚杆支护在操作上可行性。综上研究后认为,在巷道围岩中等稳定条件下,窄煤柱较为合理的宽度在3m或5.0m左右较为合适。5 沿空掘巷围岩控制技术5.1沿空掘巷围岩控制要求根据施工实践,沿空掘巷扩压控制的基本要求如下:(1)要使巷道两帮煤体在动压影响下不松散垮落,使其能完整的整体移动,减少巷道的变形量;控制巷道的形状。使巷道两帮及顶底板产生均匀的变形,使巷道在最大程度上满足生产上的需要。(2) 提高沿空掘巷上覆岩层的压力拱!结构的稳定性是保证巷道稳定的关键。必须首先控制巷道两帮的位移,提高巷道两帮的承载能力。(3) 控制巷道两帮变形,减少矿压对巷道的作用力,使其变形量减少。5.2沿空掘巷时间确定为使沿空巷道能够很好的得到维护,要正确掌握沿空巷道相对于上区段回采工作的合理滞后掘进时间,即沿空巷道必须在上区段回采引起的围岩移动和冒落过程结束后再开始掘进。一般来说,其滞后时间不会少于23个月,通常为46个月,而少数情况则要求滞后1年以上。5.3沿空掘巷围岩控制技术分类目前用于沿空巷主要控制方法有梯形棚子支护、锚网支护、U型钢支护、开掘卸压巷等。下面进行分析。5.31梯形棚子支护沿空巷道大多采用矿用工字钢梯形棚子支护,这种支护具有结构简单和安设拆卸方便的优点,但其承载能力和支护强度过低,不能主动承载,抗侧压变形能力弱,对围岩变形的控制能力小,支架本身没有可缩性,远不适应围岩变形高达1000m的沿空巷道。5.32锚网支护锚网支护就是采用锚杆、钢带配合菱形金属网组合支护的一种形式。通过锚网加固岩体,使围岩本身达到支撑自身及上层岩体的目的。由于锚网支护为主动式支护,改变围岩的力学性能,能有效承受围岩变形并提高其强度。一般沿空巷采用锚网支护能够满足要求。近年来,锚网支护在矿山得到不断推广取得了良好的经济效益。但在锚网支护中常有冒顶现象发生,使人们对其有了进一步的认识。锚网支护适用于大变化的沿空掘巷,当两帮累计移近量达1300mm、顶底板累计移量达1200mm时,巷道围岩松动和破坏仍能得到有效控制,巷道支护状况安全,仍可用于通风。但由于通风量的需求不得不重新刷大断面,以满足生产需求。该矿施工的35410风巷就发生了上述变形情况。5.33U型钢支护U型钢可缩性支架能有效控制巷道围岩的强烈变形,但若受力条件恶化以后,支护强度降低,将难以控制岩变形,而且在采动影响期间,支架也会大量损坏。因此,在支架与围岩之间及采空区侧必须实施壁后充填,使支架、充填体和围岩三者形成共同的承载体系,才有可能提高支护强度,降低围岩变形量,有效地改善沿空巷道的维护。5.34开掘卸压巷卸压巷沿煤层顶板布置在沿空巷上帮,使沿空巷周边煤岩体的高应力区向煤体深部转移。施工方法:在距采空区留2m煤柱,先施工卸压巷。巷道基本稳定后与卸压巷中心距6m开掘沿空巷。通过卸压巷布置能使沿空巷周边位移及围岩应力有大幅降低。查阅资料得出结论沿空掘巷改用锚、网、梁支护后,巷道支护质量得到很大改观,可以说锚网梁索支护技术在沿空掘巷的应用是成功的,其突出优点表现在: 降低了巷道支护成本,减轻了职工的劳动强度,提高了工作效率,巷道维护效果好,辅助工作量小,且为以后的工作面回采创造了良好的条件,节省了大量的材料,节支降耗效果显著,安全可靠性大。6 工程实例6.1 七五煤矿沿空掘巷无煤柱开采技术实践6.11七五煤矿概况七五煤矿位于山东滕南煤田中部,改扩建后生产能力为60万t/ a,现主采煤层为二叠系山西组第3层煤,分为三上煤和三下煤,其层间距平均为25.3m、为低沼气矿井;三上煤厚3.8 5.0m,三下煤厚2.2 2.8m,倾角都在516,为稳定的中厚煤层,自然发火期16个月,但煤质很硬,f 为2.52.8,三上煤抗压强度为29.478.4MPa,大于三下煤强度;这两层煤直接顶物性特征基本相同,抗压强度在68.698MPa,为中等至难冒落顶板,区别在于三上煤直接顶为碳质泥岩,厚约1m左右,而三下煤顶板岩性直接为砂岩,仅局部见薄层泥岩为其伪顶,三下煤顶板比三上煤顶板更坚硬而裂隙发育。沿空掘巷技术在该矿自80年代初期伴随着锚杆支护的推广而开始采用。推广初期,大都采用留设小煤柱的方法, 一般在5m左右,巷道位于支承压力范围内,给巷道维护与管理带来很大困难。经过几年实践探索与现场研究分析,逐渐摸清了沿空掘巷矿压显现规律,提出相应的技术管理与现场施工保障措施。6.12 沿空掘巷应用方式沿空掘巷分为完全沿空掘巷和留设小煤柱的沿空掘巷,前者更易于维护, 煤炭回收率高,适于老空积水少、老顶矸石破碎、低瓦斯矿井。推广初期,煤层赋存浅,大约在-150m以上, 适合于完全沿空掘巷;随着矿井开采深度的加深,在-150 -300m这一阶段开采时,由于矿井断层增多、上区段老空顶板砂岩水加大,需要采用留设小煤柱沿空掘巷。煤柱留设主要防止老空积水、有害气体及大块矸石窜入巷道内,在上述前提下,小煤柱越小越好,特别是沿空掘巷需要做进风巷时,留设小煤柱更是有必要。6.13 窄煤柱尺寸的确定从理论上讲,沿空巷道布置在靠近采空区塑性变形区即应力降压区,小煤柱的宽度与巷宽之和必须小于塑性变形区的宽度,才能保证下区段上顺槽是安全的。塑性变形区宽度与顶底板岩性、煤体性能、开采深度与工艺等因素有关,需要采用工程类比法与矿压观测相结合,并通过实践摸索,确定最佳煤柱宽度。初期参考枣庄局邻矿参数,煤柱从20m宽逐渐缩小到三上煤留设3m、三下煤留设4m宽,但在掘进过程中巷道承受压力仍然很大。掘后一个月,压力显现明显,至回采时刚性工字钢支架下宽收缩160220mm,20%左右的棚梁变形;特别是回采期间,超前压力影响25m左右范围内钢棚变形破坏严重,帮膨梁变,修复量很大。分析认为,塑性区宽度较邻矿小,留设煤柱过大,稳定时间长;在下一步沿空掘巷中,又陆续试验留设2.5m、2m、1.5m等几种煤柱沿空掘巷,采用的方法是分别在三上、三下工作面顺槽选择一条沿空掘巷,通过调整中线的办法分别使巷道控制在50100m范围内留设不同尺寸的小煤柱,如图6-1。现场观测统计情况见表6-1。图6-1 煤柱分段示意表6-1 不同煤柱尺寸巷道支护与变形观测统计从表6-1可以看出, 适应七五矿实际情况的小煤柱尺寸应该是2m以下, 考虑到防水、防矸及施工方便, 选择为1.5 2m之间, 即巷道中到中距离为4.55m, 实践证明了其合理、有效性。6.14 巷道施工滞后时间沿空掘巷从理论上必须建立在老空区上覆岩层趋于稳定、再生顶板重新胶结的基础上, 因此采后掘巷时间间隔越长越好。但现场采掘实际需要, 特别在区段双翼开采的情况下, 又决定了滞后时间不能太长。根据七五矿经验, 一般3个月后开始施工, 效果较好, 巷道施工后, 钢棚支护下宽收敛3056mm, 基本稳定;锚喷支护变形曲线见图6-2。图6-2 3211工作面上材料道U- T曲线6.15沿空掘巷支护沿空掘巷支护应根据具体情况采用不同的措施,坚持以护为主、支护兼顾的原则来处理,七五矿采用工字钢棚支护和锚喷支护两种方式。(1)钢棚支护在三上煤中,顶板泥岩较厚,护帮、护顶是支护的重点;而在三下煤中,由于顶板完整、强度大,沿空护帮则是重点,除了使用加密板枇外,再附加竹笆。钢棚支护的巷道在我矿占到全部沿空掘巷70%以上。(2)锚喷支护3211上材料道原设计为木棚支护,后改用锚喷支护,其参数为锚杆长1.3m, 间、排距0.8m0.8m,喷厚50mm,与原设计相比每米巷道节约68.34 元,降低成本26.2%。采用锚喷支护的沿空巷道根据上帮与顶板破碎情况,可以适当加金属网或竹笆;施工中采用喷锚喷工序能够及时维护顶板与围岩。由于锚喷支护是主动支护,能够适应沿空掘巷靠近老空区上覆岩层不稳定带来的压力变化,特别是对掘进滞后期较短的沿空巷道更为适合。6.16技术经济效益沿空掘巷技术在七五煤矿推广应用10多年,经济效益显著。在安全生产方面,顶板管理维护容易,杜绝了死亡事故;自1990 1997 年,七五矿回采巷道总计43030m, 其中沿空掘巷计20052m, 占有46.6%, 多回收煤炭资源886699t, 创经济效益3369万元。6.17 结语(1)沿空掘巷技术要根据各自现场的实际情况,选择适合自身特点的应用方式及技术措施与参数;(2)在应用该项技术过程中, 不能固守一种应用方式或一种技术参数,要寻求支护效果好、经济效益最为显著的应用方式和技术保障。6.2 邢台煤矿沿空掘巷无煤柱开采技术实践6.21邢台煤矿概况22311 (顶)综采工作面位于22300采区下部,上与22310 综放工作面采空区隔F13一l断层相邻,下与22312 综放工作面采空区相邻,属孤岛型煤柱工作面。所采2#煤层为复杂结构的厚煤层,平均厚度6m,坚固性系数f为1 1.5。煤层伪顶为厚。0 0.9m的黑灰色泥岩,破碎,具水平层理;直接顶为厚0 3m 的灰黑色粉砂岩,具水平层理;老顶为厚8 21 m 的灰白色中细砂岩,细粒结构,分选良好;直接底为厚6m 的黑色粉砂岩,含植物化石和细小云母片。22204 (顶) 综采工作面位于下水平22200 采区中部,西靠22202 (顶)工作面采空区。设计区域内煤层为一单斜构造。煤层伪顶为厚。0 0.3m 的黑色泥岩;直接顶为厚2. 5 14 m 的灰黑色粉砂岩;老顶为厚8m 的灰白色中粗砂岩;直接底为厚1.4m 的灰黑色粉砂岩。6.22支护参数设计两条工作面巷道均采用钻爆法掘进。巷道采用矩形断面,规格为3.72.8 (m )。顶部采用树脂锚杆、金属网、锚索和钢带支护,两帮采用树脂锚杆加金属网支护。(1)煤柱留设22311 运输巷沿空留设煤柱宽度3m。22204 运输巷沿空留设煤柱宽度为37m。(2)顶板锚杆采用直径22mm、长2200mm的高强螺纹钢锚杆,树脂全长锚固。每排布置5根锚杆,间排距为900900mm。(3)锚索采用直径15.24的预应力钢绞线,长6m。锚索成组布置,间距为1800mm。组距为800mm。(4)两帮锚杆采用直径16mm、长1900mm的钢筋锚杆,端头锚固。每侧帮布置4排锚杆,间排距为900700mm。6.23施工技术难点(1)采深大、压力大22311(顶) 和22204 (顶) 这两个工作面埋深分别为一450 490rn和一400 一525m,采深大、压力大。(2)动压下沿空掘巷23111综采工作面下邻22312综放工作面采空区,其运输巷受采动影响,顶板裂隙较多,围岩的稳定性差。22204运输巷紧邻22022综采工作面采空区,由于处于向斜盆地底部,约200rn巷道受到22202 工作面的采动影响(停采不到两个月),是在动压下掘进。(3)老空水影响22204运输巷由于处于向斜盆地底部,还受相邻老空水影响,顶、帮均受到水侵蚀,不易维护。为此把煤柱宽度由3m逐渐加大到7m。6.24矿压观测为找到锚杆支护下沿空掘巷的围岩活动规律藉以评价支护效果,支护后进行了矿压观测。在煤柱尺寸3m、5m和7m处各设1个矿压观测站,主要观测围岩收敛情况、锚杆受力、锚杆的预紧力和锚固力。(1)观测方法与要求观测围岩位移量采用中腰线十字布点,使用钢卷尺测量,精度为士0.5mm。取同一断面的顶板中间和两端这三个位置分别安装测力锚杆,配合YJK 型静态电阻应变仪,观测顶板锚杆的轴向受力状况。对锚杆的锚固力和预紧力以不低于10 %的比例进行抽检。(2)观测结果22311和22204 这两条运输巷在掘进和回采两个阶段的测站观测期均为30 天。22204运输巷的观测站没有进行锚杆受力观测。(3)围岩位移经过对围岩位移量的观测数据统计整理,发现顶板及两帮的位移量随时间的变化规律大致相同。其位移量及位移速度分别见表1和表2,变化曲线基本形态分别见图1和图2。从观测结果看,围岩的位移过程大致可分为掘进影响阶段、相对稳定阶段和回采影响阶段。当煤柱宽度为3m时,22311和22204两运输巷受采掘剧烈影响时间大致相同,但22311运输巷的位移速度和总位移量明显小于22204运输巷。在22204运输巷,不同煤柱宽度的位移量随时间变化的规律大致相同,但煤柱宽度为3m 的总位移量和位移速度相对较小。表6-2 顶板下沉量及下沉速度表6-3 两帮移近量及移近速度图6-3 顶板下沉量与时间关系图6-4 两帮移近量与时间关系曲线(4)锚杆受力由于安装不当,1#和3#测力锚杆在锚固力测试中损坏,只有2#测力锚杆能正常工作。对观测数据统计整理后得到了测力锚杆的轴向载荷,见表6-4。掘进期间测力锚杆的工况如图6-5 所示。表6-4 测力锚杆轴向载荷分布 (单位:kN)图6-5 22311 运输巷掘进期间2#测力锚杆工况由表6-4、图6-5可见,顶板锚杆最大轴向受力为76.6kN (杆体中部)。杆体受力持续稳定增长说明全长锚固锚杆对顶板变形具有及时、有效的约束作用。(5)锚杆的预紧力与锚固力经不定期抽检,顶、帮锚杆的锚固力均分别大于130kN和50kN (非破坏性检测、非最大值),预紧力矩分别大于80N.m 和50N.m,均符合公司及矿有关规定。6.25支护效果分析从观测结果看,22312 和22204 这两条运输巷沿空掘巷采用锚、梁、网加锚索的支护方案是合理的,总体支护效果良好。这主要表现在以下几方面:(1)围岩位移量较小。顶、帮均采用树脂锚杆支护,主动支护的特性得到充分体现,围岩位移量显著降低。22311运输巷顶、帮位移量分别为171mm和242mm,22204运输巷顶、帮位移量分别为296mm和460mm(煤柱宽度为3m )、313mm和524mm(煤柱宽度为5m )、342rnm和557rnm(煤柱宽度为7m )。而根据相关资料,在类似围岩条件下及大致相同的观测时间内,若采用架棚支护,顶板下沉量一般在600mm以上,两帮移近量一般在1500mm以上。(2)从顶板离层仪的观测数据看,顶板下沉大部分产生自锚杆锚固区以外(2 6m )。这主要是受相邻采空区的采动影响,顶板的整体性和稳定性差所至。后期观测数据表明,22311和22204 这两条运输巷的围岩基本呈整体式移动。(3)22204 运输巷顶、帮的位移量均大于22311运输巷,尤其是在回采期间的剧烈影响阶段。其主要原因是与22311工作面相邻的22312综放工作面采空区比与22204工作面相邻的22202工作面采空区停采时间长,围岩较稳定,而22202工作面采空区停采还不到两个月,22204 运输巷基本上是在动压影响下掘进的另外,22204 运输巷在煤柱宽度为5m和7m时所受采动压力峰值影响比煤柱宽度为3m时严重。由此可见,在22311和22204 这两条运输巷留设3m 的煤柱是较为合理的。(4)顶、帮锚杆和锚索仍有较高的强度储备。从围岩的变形速度分析,围岩中在锚杆锚固范围内形成了整体而较稳定的组合梁,与起悬吊作用的锚索有机结合,为试验的成功奠定了基础。6.26 结论实践证明,沿采空区(包括放顶煤采空区) 留设窄煤柱掘进时采用锚杆支护是可行的,并取得了用架棚支护所难以达到的支护效果。对2231 1和22204这两条运输巷的矿压观测表明,留设3m 宽的区段煤柱是较为合理的,能有效地避开采动压力峰值的影响。此次观测对今后沿空掘巷锚杆支护区段煤柱的留设提供了可靠依据。安装、拆卸且安装时不需扫孔,方便快捷;支护成本低,每套锚杆价格比树脂锚杆降低30%以上,并可回收复用且回收操作方便,回收率达100% ,有利于煤巷锚网支护技术的大面积推广应用。自固式注浆锚杆可连接注浆管路对围岩和煤帮进行注浆加固,有利于巷道变形、底脸和片帮的治理。该锚杆的应用为完善软岩巷道及底板的锚注加固支护技术增添了新的途径。自锚固注浆锚杆于2001年开始在淮南潘一矿、潘三矿、谢桥矿、谢一矿、新庄孜矿煤巷的煤帮锚固支护和软岩巷道及底板锚注加固中应用,取得较好的效果。参考文献1 李学华,张农,候朝炯.综采放顶煤面沿空掘巷合理位置确定.徐州:中国矿业大学学报, 2000 (2)。2钱明高,石平五.矿山压力与岩层控制.徐州:中国矿业大学出版社,2003。3徐永忻.采矿学.徐州:中国矿业大学出版社,2003。4 温大维.沿空掘巷浅析.河北:河北煤炭出版社,1981。5 于守财,浅析沿空掘巷技术及其发展.云南:民营科技出版社,2012,2。6 盖增雪.浅谈沿空掘巷在吕家坨矿业公司的应用和推广.河北:河北煤炭出版社,2012。7 申骏超,沿空掘巷围岩控制技术研究.山西:煤煤炭出版社,2012。8 李成银,张彬,王公忠.沿空掘巷技术的应用.徐州:采矿与安全工程学报,2001。9 任立君.板石煤矿12011工作面沿空掘巷围岩控制技术研究.山东:山东煤炭科技出版社,2010。10 牟彬善,吴兰荪,刘现贵,徐鸿明.沿空掘巷无煤柱开采技术实践.北京: 煤炭科学研究总院北京开采研究所,1999。11 胡计平.邢台矿沿空掘巷锚杆支护及矿压规律研究.南京: 中国煤炭工业协会煤矿支护专业委员会,2004。英文原文Movement characteristics of Karst water in a deep mining areaCHAO Chen-ming1,BAI Hai-bo2,MIAO Xie-xing2,3,YAO Bang-hua3 1China Coal Research Institute,Beijing 100013,China 2State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of MiningTechnology, Xuzhou,Jiangsu221008,China3School of Sciences,China University of MiningTechnology,Xuzhou,Jiangsu 221008,ChinaAbstract:In order to study the movement characteristics of groundwater in a deep mining area and solve the dispute of the distribution rule of hydrochemical zoning which is contradicted by lixiviation water zoning in a horizontal direction, we directed our attention to the source Of degroundwater, its seepage and hydrochemical characteristics in a typical mining areaWe used a neotectonic water-control theory,chemical and isotope methods, as well as a method for analyzing dynamic groundwater conditions.The results indicate that 1)Karst water in the deep and medium parts of this mining area is recharged by vertical leakage through neotectonic fractures rather than seepage along strata from subcrop parts or surrounding flows;2)From surface to deep leakage paths, the variation in the types of chemical groundwater agrees with the normal lixiviation water distribution rule and the age of mixed groundwater increases;3)The warer-rich zones along neotectonic fractures correspond with water-diluted zones in a horizontal direction;4)The leakage coefficient and water capacity of aquifers increases during the flow process of Karst water along the antidip direction(from west to east)and 5) Karst water in shallow mining areas forms a strong runoff belt along strikes and quickly dilutes the water from deep and mediuln mining areas. Overall, chemical and dynamic water characteristies actually agree with in terms of the entire consideration for differences in vertical leakage and abnormalities in the zone of water chemical distribution, along a horizontal runoff directionKeywords:deep mine area;Karst water;vertical leakage;water chemicals;dilution1 Introduction A number of studies demonstrate that the extent of mineralization of Karst water increases,with its chemical water type changing gradually and regularly from HC03-,Ca2and Mg2to S042-, Ca2,Mg2 and finally to Cl-,Na+,along the direction of flow. However,the opposite phenomenon is found in some mining areasTake the Luan mining area as an example,where precipitation water is the only recharge source for groundwaterBoth the extent of its mineralization and its chemical groundwater type obey the rule,along the dip direction,mentioned above(from east to west),which seems to indicate that groundwater flows deep into the mining areaOn the other hand,the flow direction of groundwater should be against the dip direction(from west to east)for the simple reason that the water head in the west is higher than in the eastIn the pastmost exploration and geological studies show that Karst water in this deep mining area is recharged by Karst water from the shallow parts along this stratum or from surrounding flows. As a result, misunderstanding arise. Based on our investigations and studies in this areaover many years,we attempt to demonstrate that the recharge source,channels and chemical type distribution characteristies of deep Karst water in this mining area agree with the direction of its movement,i.e. from west to east,by studying several aspectsThese aspects include neotectonic fractures and their ability to control water distribution and movement, the dynamic water environment,stable isotopes and radio ones,paths and conditions of vertical leakage,etc2 Recharge source of deep Karst water and its mode21 Landform characteristics around the basin The Lu-an mining area is located in the Chang-zhi basin which is in the southeast of Shanxi Province and consists of the Wuxiang,Xiangyuan and Changzhi basins,with their central elevation of 900 mThe eastern side of the basin is the western slope of the Taihang MountainThere are many Torso Mountains and loess hills accumulated bv tlle effect of erosion on the eastern side ofthe mining area where the average elevation is between 1000 m and 1200 mThe Taiyue Mountains is situated to the west of the basin. With the elevation 0f its main peak at 2567 m,while the average elevation ofthe surface watershed in this area is between 1600 m and 1800 mIn the south, the Fajiu Mountains separate the Changzhi basin from the Jinclleng basinIn the north,it borders on the Jinzhong basin through a watershed in the Wuxiang basinThe southern,western and northern sonrce regions of the Zhuozhang River are all in this basin,where rainfall is the only source ofwater recharge for the entire water resonrce in the Changzhi basinBoth surface water and groundwater eventually flow into the Zhuozhang River and then flow out of the Taihang Mountains,without any other river passing through this area Geologically,the mining area belongs to the eastern margin 0f the Qinshui coal field and its overall strike is south-north, with a slight westward deflectionOutside the coal deposit subcrop(east side)is a point with exposed dissoluble rocks of the Cambrian-Ordovician system,where new Karst on the surface and underground is developedThis is recharged by both rainfall and local surface water and water deep in the mining area slowly moves and changes 22 Neotectonic movement and distribufion characterisfics of neotectonic fractures The neotectonic movement starts in the Pleistocene. This area is not only affected by the tensile stress field caused by the subduction of the Pacitic plate,but also by the impact stress fieId produced by the collision between the India and Eurasian plates. It survived the genesis of two rift valleys in the Tertiary Period with the uplift of the entire Shanxi-Shaanxi plateau(the second step),reviving and reproducing new crannies and cracks, resulting in the formation of relative subsidence in this mining area The eastern mountain area of the Changzhi fault rises by 670 m while the western Changzhi basin decreases by 290 m,so that the difference in height between both sides increased by 960 mThe Taihang Mountains rises by 410 m,reinforcing the erosion ability of the riversDuring the first occurrence of the neotectonic movement, the Zhuozhang River cut off the Taihang Mountains,captured the water system of the ancient Changzhi Lake and caused it to disappear graduallyThe height difference between the eastern and western sides of the Taihang Mountains is so great that the effect of incision by rivers in the western side becomes quite intensive,with a relatively low erosion base-level,so that the depth of buried of groundwater increasedConsequently,the groundwater flow deep into the earth and the depth of the Karst increasedIn the mining area, many old structures,especially some faulted structures,revive and move in different periodssuch as the horst of the Wenwang mountains,the horst of the Ergang mountains,as well as the Changzhi and Lucheng faultsAt the same time,there are some new structures such as the Wangzhuang-Changcun fracture zonesThese newly produced fracture zone-consisting of a series of dense small fracture zones,have no uniform and fixed main horizontal fracture direction(one ofthe reasons why they are not found and identified by past geological coal explorations),leading the drop in height between the two sides of up to 50 mA steep slope in a NWW direction was produced in the landform which caused a height difiefence of up to 30一50 m in the terrain. These newly produced and reactivated neotectonic fracture zones run through shallow and deep parts of the mining area and divide it into different parts(Fig1)Fig1 Hydrogeology concept model plot23 vertical leakage recharge mode The reactivated old fractures and newly produced ones have become the main leakage channels for surface water to recharge Karst water deep in the mining areaUnder the strata of the coal deposits Ordovician Karst water is recharged by the Carboniferous-Permian fissure water,mentioned earlier,which is replenished by pore water of the Quaternary system,i.e ,the final recharge source is rainf-all and surface waterThe groundwater level of the Quaternary systern in this mining area ranges from+900 m to+930mthe level of hydraulic pressure water in the pores at the bottom of the Quaternary system is+960+880 mThe level of water in sandstone fissures of the Permian is between+770+790 m,the level of the water in limestone-fissures ofthe Carboniferous is +750+770 mEven in the Ordovician Karst aquifers,the water level in the Fengfeng Formation at the topexceeds that of its lower Majiagou Formation by l()-40 m, which is the driving force for vertical leakageThe difference between water levels of the Quaternary system and that of bedrock fissures and Karst is so large that a non-pressure area is formed at the top of the bedrock,which means that the amount of recharge of bedrock water from the Quaternary system almost remains constantThis recharge mode is illustrated in Fig2 with arrowsFig2 Vertical leaking recharge model outline3 Runoff characteristics31 Main runoff direction The level of Ordovician Karst water declines from west to east, with the high level(+660 m) in the Tunliu Mine(deep area),at a medium level(+650 m) in the Changcun Mine and a low level(+643 m)in the Wangzhuang Mine respectivelyThis indicates that the flow direction of Karst water is from west (deep) to east(shallow)along the antidip direction. It is the point where some earlier hydrodynamic explanations are contradicted by past chemical distribution rules of water, i.e. the flow direetion of Karst water should be from west to east judging from the water headOn the basis of the number of chemical water ions and their distribution rules. It seems that Karst water seeps from east(shallow)to west(deep)along the dip after being recharged at the outcrop32 Development features It is owing to the fact that Karst in this area either belongs to the old Caledonian-Hercynian period or to the new tectonic movement period that water cycle conditions are differentFor this reasonold Karst mainly exists in the Fengfeng Formation(at the top of the Ordovician)and new Karst only evolves into horizontal multistrata Karst caves,based on old Karst on the surface or in shallowburied areasThe three cyclothem of the Ordovician system enable new Karst,inthe shallow parts,to develop and behave as strata-controlling Phenomena with strong and weak interlacingThe effect of dissolution of gypsum leads,in turn,to the appearance of a dissolved breccia zone,a crushed rock zone and a fracture zone above the gypsum stratum and a strong regional water-bearing stratum(from the bottom up)formed under the effect of further dissolutionThe interaction between a strong runoff zone in the shallow and weak parts,opposite the dip and penetrating from the shallow to the deep part,limits the size of the area for dissolved CaC03 and MgC03It is in the shallow part where both the new and old Karst interact;Karst of the Caledonian period at medium depth is filled by sediment3.3 Water capation of neoteetonic fractures The reactivated old fractures and newly produced fracture zones are fan-shaped horizontally and link the weak,middle and strong water-rich Ordovician areaswhich become the main leakage channels for groundwater in the shallow parts to recharge deep Karst water as well as the collection places for Karst water on both sidesThese neotectonic fractures receive recharge water through vertical leakage and horizontal seepage from both sides and flow into the centralized runoff channels to discharge simultaneously(Figs1 and 2)4 Chemical characteristics41 Distribution characteristics of constant ions The media in Karst water of this mining area are carbonate and sulfate rocks,which suggests that the chemical compositions in Karst water are mainly Ca2+,Mg2+,HC03- and S042-The water chemicals gradually change from HC03-Ca2+, Mg2+ toS042-Ca2+,Mg2+,which seems to agree with the characteristic of lixiviation watert,i.e., the direction of groundwater flow is from east to west and the extent of its mineralization increases and changes from HCO3-Ca+, Mg+ to SO42-Ca+,Mg+ and eventually becomes a Cl-Na+ , K+ water type,with an increase in flow distance. Essentially,the formation model of lixiviation water in this area is different from that of normal lixiviation wateralthough it is formed under lixiviationThe great difference for Karst in a vertical leakage coefficient and in water-rock interaction over time,leads to huge differences in the extent of mineralization before the water reaches the aquifcr through vertical leakageTo the west of the mining area,the buried depth of the Ordovician is so great,that the extent of mineralization of Karst water is high as a result of the high mineralization level of recharge water through vertical leakageThe level for recharge water through vertical leakage is low due to the shallow,buried depth in the east and so Karst water is dilutedAt the same time,the ability of water to renew itself in neotectonic fractures is better than that of both sides and so it can obtain more recharge water in shallow parts through leakage,forming a water dilution zone(Fig.1).4.2 Saturation index and characteristics of dissolved material From the calculation of the saturation indices of the main minerals in Karst water,like calcites,dolomites and gypsum,we found that the carbonate minerals are in a dissolved state to the east of the mining area with the amount of Karst still becoming larger,while they are in a state of saturation in both the middle and the west of the mining area with the saturation level and the degree of fill by sediment becoming higher towards the westSulfate minerals in most places are in a dissolved state and tend to be more saturated from east to westA11 old Karst in the west is being filled and becomes compactable43 Distribution eharacteristies of stable isotopes The Changcun mine lies,in a horizontal direction,in the deep part between the An-Chang graben and the Wenwang horstIts western place, 18O is from -0994to-1163and D is from-717 to -808which is the minimum value in this area. 18O, in the area from the Wenwang horst and the Huangnian town to Lucheng town ranges from -0894 to -0947and the D is between-6-3 to -73, which are the maximum values in this areaIn contrast, the 18O and D in deep Karst water are lower over the large recharge distance and are mainly recharged from remote mountain areasCorresponding values in the east(shallow)are higher over small recharge distancesThis proves that the main recharge source and areas for deep and shallow parts of this mining area are different. In the vertical directionthe 18O and D in water of the Quaternary system are larger than in fissure water of the Carboniferous-Permian system which in turn are larger than the values in Karst water of the upper parts of the Ordovician(02f) and the least in Karst water of the lower part of the 0rdovician(02f+s)The proportions of 18O and D in water of the Quaternary syrstem are_一082076 and -658一567 respectively,while corresponding values in the water of the CarboniferousPermian system are109094and-728_717respectivelyValues in Karst water of the upper part of the Ordovician(02f) are usually higher than those in Karst water of the lower part of the Ordovician (02f+m)from the same drill hole,which indicates that upper Karst water in deep places is recharged by overhead water bodies with a high level of isotopes (compared with the number of isotopes in Karst water) or waterbearing strata44 Distribution characteristics of radio isotopes In a horizontal direction,the residual volume of 3H in eastern Karst water is significantly larger than that in the west with a difference of one order of magnitudeThe volume of Karst water deep in the mining area is usually below 2 TU,which indicates that its leakage path is long and the age of groundwater increases In this section,from pore water ofthe Quaternary system and fissure water of the CarboniferousPermian system to Karst water of the Ordovician,the residual volumes ofH become smallerThis difference in residual volume exists even between the Fengfeng and the Majiagou FormationsThe residual volume ofH in groundwater of the same stratum is also higher towards the east and lower towards thewest,while that for both precipitated water and surface water is consistentThese difrerences indicate that groundwater receives its recharge from rainfall and surface water through leakage(from top to bottom)and its age increases with a much smaller leakage velocity in the west than that in the east.5 Conclusions 1)The recharge source for Karst water deep in the mining area comes from water in the higher western mountain areas through vertical leakage,which is proven by the differences in water levels of each stratum,their stable isotopes and residual volumes of 3H 2)In a horizontal direction,Karst water flows along the antidip from a deep,stagnating flow area where the amount of water is small, to a strong runoff area in shallow places which contain abundant waterThe leakage coefficient and the amount of leakage both increase from west to east and the recharge source of Karst water becomes fresher when the age of the mixed water decreases 3) The main channels for vertical leakage and horizontal runoff are neotectonic fractures which connect deep and shallow parts of the mining area The fact that their mixed water is fresher than the surrounding water shows that the recharge and runoffconditions are excellentReferences 1 Wang J BThe chemical action of Karst water compositions of the Ordovician in Lu-an mining areaCoal GeologyExploration,1999,27(2):39-42(In Chinese) 2 Liu F ZPreliminary exploration on karst developing causeGroundwater, 1998,20(2):70一73(In Chinese)3 Hanshow B B,Back WMajor geochemical processes in the evolution of carbonate aquifer systernsHydrol,1979f43):2873 12 4 Toth JGroundwater as a geologic agent:an overview of the causes,processes,and manifestationsHydrogeology Journal,1999(7):1-14 5 Collins A GGeochemistry of Oilfield Waters(Development in Petroleum Science nAmsterdam Oxford New York:Elsevier Scientifie Publishing Company,1975:34一165 6 Duan L,Wang W I(,Cap Y QHydrochemical characteristics and formation mechanics of groundwater in the middle of northern slope of Tianshan mountainsJournal ofArid Land Resources and Environment,2007,2l(91: 29_34(In Chinese) 7 Xu H Z,Duan X M,Gao Z DHydrochemical study of karst groundwater in the Jinall spring catchmentHydrogeologyEngineer Geology,2007(3):15-19(In Chinese) 中文译文深矿区喀斯特水的运动特征曹成明1,白海波2,缪协兴2,3,姚邦华31中国煤炭研究所, 北京 1000132 中国矿业大学“地质力学和地下工程”国家重点实验室 江苏 徐州 2210083 中国矿业大学科学院 江苏 徐州 221008摘要:为研究深矿区地下水的运动特征,解决咸水入侵分区的分布规律与水平方向溶隙水分区相矛盾的问题,我们主要把注意力集中在深层地下水的水源、渗漏以及典型矿区的喀斯特水特征。其间,我们运用了新构造控水理论、化学同位素方法以及用于分析动态地下水的方法。研究结果如下: 1)中深矿区喀斯特水的补给来自断层构造的垂直裂隙渗漏,而不是来自隐伏露头或围岩中的隙流水。2) 随着深度增加,垂直渗入路径、化学地下水种类发生的变化与正常溶隙水的分布规律一致,混合地下水所属的年代逐渐提前。3)沿断层构造发育的富水带与水平方向被稀释的地下水的分布区域吻合。4)喀斯特水沿反倾斜方向流动的过程中,渗漏系数和蓄水层的含水量都有所增加。5)浅矿区的喀斯特水会沿走向冲击形成一条强径流带,迅速稀释中深矿区的地下水。总之,考虑到垂直渗漏和水平径流方向上水化学分布区域的异常情况,动态化学水的运动基本符合以上研究结果。关键词: 深矿区, 喀斯特水, 垂直渗漏, 水化学,稀释作用1.引言大量研究表明,化学水种类会沿水流方向逐步从HCO3-,Ca2+,Mg2+ 变为SO42-,Ca2+,Mg2+ ,最后变成Cl- ,Na+ , 导致喀斯特水的矿化度提高。然而有些矿区的情况截然相反,如潞安矿区,大气降水是该区地下水的唯一补给,其矿化度和化学地下水类型沿倾斜方向(即上文提及的自东向西)发生有规律的变化,可以推断地下水会流向深矿区。另外,地下水流向应与倾斜方向(自西向东)相反,原因很简单-西部水压高于东部水压。过去进行的地质勘探和研究认为深矿区喀斯特水的补给来自较浅岩层或周围水流,结果误解丛生。根据多年来在该领域的调查研究,笔者认为,深矿区喀斯特水的补给水源、渠道和化学种类分布特征与其自西向东的运动方向一致。我们的研究包括以下方面:断层构造及其对水流分布及运动产生的影响,动态水环境,稳定同位素,发散同位素,垂直渗漏路径及条件
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