陕北榆神矿区煤层开采顶板涌水规律分析

赵春虎1,2,靳德武1,2,李智学3,申小龙4,王 皓1,2,王世东1,2,许 峰1,2,王强民1,2

(1.中国煤炭科工集团西安研究院有限公司,陕西 西安 710054; 2.陕西省煤矿水害防治技术重点实验室,陕西 西安 710177; 3.陕西投资集团有限公司,陕西 西安 710061; 4.陕西煤田地质勘查研究院有限公司,陕西 西安 710021)

摘 要:榆神矿区是我国陕北煤炭基地的重要组成部分,针对榆神矿区煤层开采顶板覆岩含水层涌水规律研究不足等问题,通过系统分析地质与水文地质结构特征,将矿区开采煤层覆岩划分为松散孔隙、基岩与风化裂隙、烧变岩孔洞裂隙4个含水层组,以及主、亚2个隔水保护层组;根据煤层采动导水裂隙与覆岩含(隔)水层组不同组合关系下的含水层涌水特征,提出了浅埋煤层侧向直接涌水、中深煤层侧向与垂向复合涌水,以及深埋煤层侧向涌水与垂向弱涌水3种含水层涌水模式;并采用数值分析方法,以榆神矿区典型矿井为研究对象,构建了采煤工作面尺度上煤层开采3种模式涌水分析模型,模拟结果显示,浅埋煤层侧向直接涌水型(凉水井井田),主采煤层为4-2煤层,采动导水裂隙直接发育至松散含水层,工作面顶部含水层被疏干,总涌水量为47 m3/h,地下水流场受采动影响大;深埋煤层侧向涌水与垂向微涌水型(小壕兔1号井田),主采煤层为1-2煤层,采动导水裂隙发育至基岩含水层,总涌水量为21.87 m3/h,以侧向涌水为主,由于主、亚隔水层复合保护,垂向涌水微弱;中深煤层侧向与垂向复合涌水型(曹家滩井田),主采煤层为2-2煤层(均厚约为11 m),在分层开采条件下导水裂隙发育至基岩含水层内部,其侧向涌水量为23.17 m3/h,垂向涌水量为12.67 m3/h,地表松散含水层地下水流场变化较小,在一次采全高条件下导水裂隙突破亚隔水层,发育至风化基岩含水层底部,总涌水量增至131 m3/h,对松散含水层影响较大。此外,当导水裂隙带高度小于180 m、不能沟通风化基岩含水层时,随导水裂隙带高度增加涌水量增加幅度不大,当导水裂隙带高度大于180 m、导水裂隙揭露富水性较好的风化基岩含水层时,涌水量增加幅度较大,由此可见,抑制导水裂隙发育高度与覆岩强含水层的接触关系,是控制煤层覆岩涌水的一项重要措施。

关键词:保水采煤;含水层;涌水模式;导水裂隙;榆神矿区

榆神矿区地处西部干旱与半干旱地区,毛乌素沙漠与陕北黄土高原的接壤地带,是我国陕北煤炭基地的重要组成部分,近地表第四系萨拉乌苏组松散孔隙含水层是区内惟一具有供水意义和重要生态价值的含水层[1],为矿区保水采煤的目标保护层[2]。煤层开采形成的采动裂隙发育至基岩含水层内部甚至近地表的松散层含水层,导致含水层地下水沿采动导水裂隙间接或直接涌入采掘空间,一般形成大而稳定的顶板涌水问题[3],也加剧了矿区水资源短缺局面以及生态环境的负效应[4-5]。因此,煤层开采过程中顶板水害防控与地下水资源协同保护是煤炭可持续开发面临的一项主要问题。

针对矿区“煤水”协调问题,董书宁等[6-7]系统提出了西部矿区典型顶板水害防控技术,彭苏萍等[8]系统总结了煤矿区生态环境修复关键技术。李智学、申小龙等[9-10]系统分析了榆神矿区最上可采煤层赋存特征、上覆主要含(隔)水层空间分布规律及组合类型,李文平等[11]根据主采煤层上覆基岩、松散含水层及隔水层的空间分布特征,将榆神府矿区“保水采煤”工程地质条件分为砂土基型、砂基型、土基型、基岩型、烧变岩型5类,王双明等[1]根据“三图预测法”将榆神矿区划分为贫水、保水限定、可控保水和自然保水4个保水采煤类型分区。王启庆等[12]根据煤层开采对松散层潜水的影响程度,将矿区划分为不涌水、轻微涌水、一般涌水、严重涌水4个分区,邓念东等[13]把白垩系洛河组含水层也作为保水对象,将矿区划分为沙-土-洛-基型、沙-土-基型、沙-基型、无水开采区与烧变岩型5个保水开采分区,笔者[14]采用地下水数值模拟方法研究了神东矿区浅埋煤层开采松散含水层涌水量,相关研究成果丰富了矿区保水采煤技术实践。

目前保水采煤理论与技术主要以“覆岩分带理论”为研究基础,以分析不同采煤条件下导水裂隙带发育高度与覆岩含水层的空间关系为研究重点[15-16],其基本认识为导水裂隙未沟通保水目标层或隔水土层,未造成地下水资源大量漏失,即认为可以实现保水开采。陕北榆神矿区分4个规划期,各期主采煤层赋存特征差异较大,针对煤层开采引起含水层涌水规律的相关研究大多集中在开采程度高、开采煤层埋深相对较浅的一、二期规划区以及北部的神府矿区,其研究成果在榆神中深部的三、四期规划区应用方面存在一定局限性。笔者通过系统整理分析榆神矿区主采煤层地质、水文地质特征以及导水裂隙带的相关研究成果,总结榆神矿区主采煤层开采含水层3种涌水模式,并采用地下水系统数值分析手段,构建了矿区典型煤矿工作面尺度上3种模式的涌水分析模型,定量分析了采煤导致的含水层地下水的涌水规律。

1 主采煤层水文地质结构特征

1.1 主采煤层赋存特征

榆神矿区位于毛乌素沙漠与陕北黄土高原的接壤地带,地貌单元上划分为风沙地貌、黄土地貌及河谷地貌3种类型,地势呈西北高东南低,地层总体表现为向北西缓倾的单斜,地质构造相对简单。

矿区含煤地层为侏罗系中统延安组(J2y),覆岩由下至上依次为侏罗系直罗组(J2z)、安定组(J2a),白垩系洛河组(K1l),新近系保德组(N2b),第四系离石组(Q2l)、第四系萨拉乌苏组(Q3s),以及风积层(Q4eol)与冲积层(Q4al)。如图1,2所示,由于地层剥蚀,侏罗系延安组含煤地层保存不完整,矿区从东南向西北可采煤层5-2,4-2,3-1,2-2,1-2呈阶梯状分布,覆岩层组合及厚度差异较大,其中东部的榆神二期主采煤层由西北向东南依次为5-2,4-2,3-1;中东部的榆神一期主采煤层为2-2,中部榆神三期主采煤层除小壕兔一、二号井田为1-2外,其他区域均为2-2;西部榆神四期主采煤层为1-2,2-2,总体上各主采煤层埋深由东至西逐步增大。

图1 榆神矿区主采煤层埋深等值线(据文献[9]修改)
Fig.1 Buried depth contour of the top mineable coal seam seams in Yushen mining area(revised according to Reference[9])

图2 矿区典型地质钻孔柱状
Fig.2 Hydrogeologic histogram of typical boreholes in mining area

1.2 主采煤层覆岩含、隔水层

根据榆神矿区主采煤层覆岩的地层岩性,以及地层剥蚀、风化、烧变等作用,划分主采煤层覆岩含、隔水层见表1。

表1 榆神矿区主采煤层覆岩含隔水层特征
Table 1 Characteristic table of overlying aquifer and aquifer of the top mineable coal seam in Yushen mining area

地层系统组类型岩性特征富水性分布特征第 四 系 新 近 系全新统上更新统中更新统上新冲积层 Q4al风积层Q4eol萨拉乌苏组Q3s离石组 Q2l保德组 N2b松散孔隙含水层隔水层隔水层以细沙、粉沙、粉土和粉质黏土为主 以固定、半固定沙丘形式覆盖于其他地层之上 以灰黄色、褐色及灰黑色粉、细、中沙为主以浅棕黄、褐黄色亚黏土及亚沙土为主,抗裂性隔水特征明显以浅红色、棕红色黏土及亚黏土,含不规则的钙质结核,抗裂隔水性特征明显弱-强极弱极弱河谷区 全区广泛分布 全区广泛分布矿内分布不连续全区大部分布白 垩 系下统侏 罗 系 中统洛河组 K1l安定组 J2a直罗组 J2z延安组 J2y风化基岩-基岩裂隙含水层风化基岩裂隙发育由上而下减弱,富水性较强于下部正常岩段,一般厚度为20 m,全区分布。矿区由西到东发育层位依次为洛河组、安定组、直罗组与延安组以紫红、棕红色中粗粒长石砾岩为主上部以泥岩、砂质泥岩为主,下部以中~粗 砂岩为主上部以泥岩、砂泥岩为主,下部以中~粗 粒长石砂岩为主含可采煤层13 层,以浅灰、深灰色砂岩及泥岩为主烧变岩孔洞-裂隙含水层因2-2,3-1,4-2,5-2煤层自燃顶板塌落及后期风化作用形成裂隙孔洞发育富水性好的烧变岩含水层中-弱弱弱-中弱-中弱-强三期规划区的西部与四期大部 一期西部,三、四期大部三期、四期全区分布,一期西部与二期西北部全区 二期各大沟谷两侧条带状分布

松散孔隙潜水含水层组,主要指第四系冲积层(Q4al)、风积层(Q4eol)以及萨拉乌苏组(Q3s),基本全区分布,一般3层具有较为统一的水力联系,一般划分为松散孔隙潜水含水层组,据矿区金鸡滩、锦界、凉水井、曹家滩、大保当、尔林滩、尔林兔等井田抽水试验资料,渗透系数0.013~23.582 m/d,水位埋深一般小于3 m,富水性大部分较好,是矿区煤层开采保水的目标含水层。

基岩裂隙含水层组,矿区主采煤层上覆基岩地层自下而上分别为延安组(J2y)、直罗组(J2z)、安定组(J2a)、洛河组(K1l)正常基岩地层,据榆神一期杭来湾、曹家滩、大保当、神树畔等井田,二期香水河、何兴梁、马王庙、朱家塔等井田,三期小壕兔一号、二号及小保当一号等井田,四期尔林滩、孟家湾西、中鸡等井田对不同基岩含水层抽水试验资料显示,渗透系数0.006~2.135 m/d,基岩裂隙含水层组富水性一般较弱。如图2所示,基岩厚度总体由东南向西北增厚,由于上部受风化剥蚀作用影响,在矿区中东部区(一、二期),洛河组(K1l)基岩地层缺失,主采煤层上覆基岩层岩性和厚度变化较大。

风化基岩含水层,基岩顶部岩石顶面受到不同程度的风化,结构杂乱,松软易碎,受地形地貌、上覆含水层特征、风化程度等影响,风化基岩含水层富水性变化较大,渗透系数0.012~4.992 m/d[17-18],矿区由西向东发育层位依次为洛河组(K1l)、安定组(J2a)、直罗组(J2z)与延安组(J2y)[19]

烧变岩孔洞裂隙含水层,是指因煤层自燃顶板塌落及后期风化等形成裂隙孔洞发育的烧变岩带,由于岩层破碎,透水性好,其富水性变化较大,主要与自燃煤层、烧变岩特征及烧变岩上覆松散含水层组的富水性有关,其分布范围相对局限,主要在二期各大沟谷两侧呈条带状分布,据锦界、西湾、榆树湾、杭来湾、上河、高家界、河兴梁等井田勘探钻孔抽水试验资料,渗透系数0.006~74.103 m/d。

主隔水层是由第四系离石组(Q2l)黄土和新近系保德组(N2b)红土共同组成的隔水土层[20],是上覆松散孔隙潜水含水层组的直接隔水底板,基本全区分布,该土层组的连续性、厚度、天然及采动后的渗透系数变化等对保护松散含水层意义重大,被定为榆神矿区的隔水关键层[21-22]

亚隔水层,在榆神矿区中-深煤层区,侏罗系地层中渗透能力弱的泥岩、砂质泥岩、粉砂岩与渗透能力较好的中、细粒砂岩相互交错,其中侏罗系安定组地层(J2a)以含泥岩、砂质泥岩沉积为主,厚度较为稳定,一般划分为相对隔水层[23-24]

2 主采煤层开采含水层涌水模式

由于采动导水裂隙具有极强的导水能力,是引起含水层涌水的控制因素,通过分析榆神矿区主采煤层开采形成的导水裂隙带与上覆含、隔水层组的空间组合关系,以及引起含水层涌水特征,提出榆神矿区最上煤层开采含水层涌水模式。

2.1 榆神矿区主采煤层采动导高分析

通过整理分析榆神矿区生产矿井导水裂隙带高度研究成果,见表2。矿区煤层埋深、覆岩结构差异明显,主采煤层开采裂采比变化较大(15~28倍),均值23倍。其中榆神东部与南部浅埋煤层区,主采煤层开采(如4-2,3-1煤层等)导水裂隙易沟通风化基岩与松散含水层(如柳巷、凉水井、锦界等煤矿);中南部中埋深煤层区,由于主采煤层2-2厚度大,曹家滩、榆树湾等生产矿井一般采用分层开采,实测分层开采导水裂隙一般发育至基岩内部,通过相似材料模拟得出一次采全高条件下导水裂隙易发育至土层甚至松散层内[21,27];中部与西部深埋煤层区,主采煤层(如2-2,1-2煤层)开采导水裂隙仅发育在基岩含水层内部(如榆树湾、金鸡滩、隆德、小壕兔等煤矿)。

表2 榆神矿区部分矿井开采覆岩导水裂隙带测试统计
Table 2 Detection results of water flowing fractured zone in some mines in Yushen mining area

矿井名称煤层测试孔号采高/m导高/m裂采比揭露层位方法曹家滩[25]2-25.00123.4024.68基岩含水层实测JSD25.50107.4919.54JT25.50109.7219.95金鸡滩[26]2-2JT35.50111.4920.27基岩含水层实测JT45.50126.4023.00JT55.50146.1826.58Y35.00130.5026.10Y55.00138.9027.78基岩含水层实测榆树湾[27-28]2-2Y45.00137.3027.465.00130.0026.00基岩含水层实测6.00148.0024.67土层相似材料模拟7.00168.0024.00H34.50108.3224.10杭来湾[29]2-2H44.50114.3825.40基岩含水层实测H54.50107.8323.96H74.5093.8720.86CH013.9675.7819.14隆德[30]2-2CH023.9671.6618.10基岩含水层实测CH033.9676.8519.41柳巷[31]3(2-2)L17.90117.8414.90松散层实测锦界[32]3-1冒13.00≥45.72≥15.24风化基岩含水层实测凉水井[33]4-23.00≥70.00≥23.33松散层实测

2.2 煤层开采含水层涌水模式

根据榆神矿区主采煤层采动导水裂隙与覆岩含(隔)水层的空间组合关系,以及不同组合关系下含水层涌水特征,提出3种涌水模式:

(1)浅埋煤层侧向直接涌水型(图3(a))。榆神矿区东部浅埋煤层区(一、二期)主采煤层开发时导水裂隙带穿越离石、保德组发育至地表风积沙等松散层内,在工作面顶部局部区段内的松散含水层被迅速疏干,该区段含水层不能得到外围含水层侧向补给,出现干涸;而工作面外围的松散含水层地下水会以侧向排泄的形式沿着导水裂缝侧向边界进入采空区内,造成松散含水层与基岩裂隙含水层地下水沿导水裂隙侧向直接涌入井下,形成典型的“侧向直接型”涌水模式。

图3 煤层采动含水层涌水模式示意
Fig.3 Schematic diagram of water inrush in aquifer under the influence of coal seam mining

(2)中深煤层侧向与垂向复合涌水型。榆神矿区中部(三期)煤层埋深相对较大(150~400 m),如图3(b)所示,采动导水裂隙直接揭露基岩含水层后延伸至离石、保德组主隔水土层底部或内部,造成基岩含水层地下水大量漏失,基岩含水层以侧向涌水为主;而采动导水裂隙与松散含水层之间残留一定厚度的隔水土层,由于基岩含水层地下水的大量漏失致使与松散含水层间的水力梯度增大,以及土层弯曲变形后垂向渗透能力提高,导致松散含水层沿主隔水土层越流涌水,李涛等[34-35]采用水-电相似模拟技术,测试得出当采后有效隔水层厚度为42.6 m的离石黄土或21.0 m的保德红土时,潜水才不会显著漏失,可见中深煤层开采易形成“侧向与垂向复合”涌水模式。

(3)深埋煤层侧向涌水与垂向弱涌水型。榆神矿区西部(三、四期)煤层埋深相对较大(>400 m),如图3(c)所示,采动导水裂隙发育至直罗组、延安组基岩含水层内部或安定组亚隔水层内,采动裂隙直接揭露的直罗组、延安组基岩含水层沿导水裂隙侧向直接涌水,安定组亚隔水层顶部的洛河组基岩含水层间接越流涌水,而近地表的松散含水层由于存在安定组亚隔水层与离石组、保德组主隔水土层保护,地下水越流漏失微弱,易形成基岩含水层侧向涌水与垂向复合隔水保护弱涌水模式。

3 典型煤矿煤层开采含水层涌水规律

3.1 采煤工作面含水层涌水分析方法

为了便于定量分析煤层开采含水层涌水规律,根据含水层与导水裂隙带间的地下水运动转化特征,将导水裂隙与正常覆岩接触面概化成地下水达西渗流的定水压边界(孔隙水压力p=0),合理避免了导水裂隙带难以数值刻画问题,其模拟结果更接近于真实的渗流场,在COMSOL数值分析中,将导水裂隙带范围概化成倒梯形,在涌水模型中分别对梯形各面达西流速U进行面积积分,即为导水裂隙带概化形成倒梯形面积采用稳定流分析方法,计算得出来自导水裂隙带外围侧向和顶部各含水层的地下水涌水量[36],以建立采煤工作面尺度上含水层涌水分析模型。

为了削弱模型边界效应影响,在采煤工作面尺度上的含水层涌水模型中,采用无限元域方法,将模拟区外围定义为无限展布的含水层[37],即将充水含水层外围数值处理成“大范围”的无限展布的充水含水层,减少了“小范围”人为水头边界与流量边界对预测精度的影响,宽度设置为3 000 m,走向为100 m,图幅显示比例调整为xyz=1∶10∶3。其中覆岩各含水层主要水力参数根据各矿井含水层实际测试资料给定(表3)。

3.2 浅埋煤层侧向直接涌水型

凉水井井田位于榆神二期中北部,主采为4-2煤层,煤层厚度0.8~4.2 m,最大埋深150 m,煤层上覆松散层孔隙潜水含水层(均厚13.46 m),离石与新保德组土层(均厚31.61 m),基岩与风化基岩含水层(一般厚度38 m),4-2煤层采动导水裂隙已揭露松散含水层,为侧向直接流失型涌水模式。

表3 模型中含、隔水层渗透系数
Table 3 Permeability coefficients of main aquifers in the model

含(隔)水层渗透系数/(m·d-1)松散孔隙潜水含水层组1.5~3.0基岩裂隙含水层组0.03~0.08风化基岩含水层0.085~1.500主隔水土层0.001~0.008亚隔水土层0.010~0.003

由于采动裂隙直接发育至松散含水层,如图4所示,地下水流场受采动影响较大,形成以导水裂隙带为中心的降落漏斗,其中工作面顶部与侧向一定范围内的含水层被疏干(空白区段),积分得出各含水层向导水裂隙的总涌水量为47 m3/h,均来自松散层、基岩与风化基岩含水层的侧向涌水。

图4 凉水井煤矿含水层流场特征
Fig.4 Characteristics of aquifer flow field in Liangshuijing Coal Mine

表4 凉水井煤矿含水层涌水量
Table 4 Water inrush of aquifer in Liangshuijing Coal Mine m3/h

导水裂隙揭露层位涌水模式含水层涌水量顶部侧向总量松散含水层侧向直接涌水04747

3.3 深埋煤层侧向涌水与垂向弱涌水型

小壕兔一号井田位于榆神四期西部,最上开采煤层为1-2号煤层,均厚4.8 m,埋深约为400 m,煤层上覆松散含水层(25 m),离石组与保德组隔水土层(48 m),洛河组基岩含水层(66 m)、安定组亚隔水土层(136 m)、以及直罗组与延安组基岩含水层(132 m),按照23倍裂采比分析,1-2煤层采动导水裂隙带高度约110.4 m,发育至直罗与延安组基岩含水层顶部,未揭露安定组亚隔水层,其涌水模式属于侧向与垂向复合隔水保护弱涌水型。

如图5、表5所示,导水裂隙对直罗组与延安组基岩含水层流场影响较大,形成较为明显的降落漏斗,由于安定组与离石组、保德组隔水层复合保护近地表松散含水层,地下水流场基本未发生变化,含水层总涌水量为21.87 m3/h,以侧向涌水为主,顶部涌水量仅为3.27 m3/h。

图5 小壕兔煤矿含水层流场特征
Fig.5 Characteristics of aquifer flow field in Xiaohaotu Coal Mine

表5 小壕兔煤矿含水层涌水量
Table 5 Water inrush of aquifer in in Xiaohaotu Coal Mine m3/h

揭露层位涌水模式含水层涌水量顶部侧向总量直罗组与延安基岩层复合隔水保护微涌水3.2718.6021.87

3.4 中深煤层侧向与垂向复合微涌水型

曹家滩井田位于榆神矿区一期规划区中部,主采煤层为2-2煤层,平均煤厚达11.20 m,埋深一般为300 m左右,采煤方法为分层综采。煤层上覆松散层孔隙潜水含水层(10 m),离石组与保德组土层(70 m),风化基岩含水层(26 m)、安定组亚隔水土层(22 m)以及直罗组与延安组基岩含水层(175 m)。按照23倍裂采比分析,2-2煤层分层开采高度为5 m,导高为115 m,发育至直罗与延安组基岩含水层中部;一次采全高10 m,导高为230 m,发育至离石与新保德组土层下部,均未贯通土层,其涌水模式为侧向与垂向复合涌水型。

如图6,表6所示,上分层开采导高为115 m时,导水裂隙发育至直罗与延安组基岩含水层内部,基岩含水层以导水裂隙为中心形成明显的地下水降落区,由于地表松散含水层受土层的保护,地下水流场基本未发生变化。各含水层向导水裂隙的总涌水量为35.84 m3/h,其中侧向涌水量约为23.17 m3/h,顶部含水层(含风化基岩含水层、土层与松散含水层)地下水的垂向越流涌水量约为12.67 m3/h;一次采全高,导高为230 m时,导水裂隙直接贯通基岩含水层,发育至风化基岩含水层底部,总涌水量增至130.31 m3/h,其中基岩含水层与风化基岩含水层侧向涌水量92.65 m3/h,由于风化基岩含水层与近地表松散含水层之间的水力梯度增大,导水裂隙顶部的含水层地下水的越流涌水量增至37.66 m3/h,导致地表松散含水层地下水流场发生明显变化,工作面顶部地下水流向发生逆转。

图6 曹家滩煤矿含水层流场特征
Fig.6 Characteristics of groundwater flow field affected by coal seam mining in Caojiatan Coal Mine

表6 曹家滩煤矿含水层涌水量
Table 6 Water inrush of aquifer in in Xiaohaotu coal mine

导水裂隙带高度/m揭露层位涌水模式含水层涌水量/(m3·h-1)侧向垂向总量115基岩含水层中深侧向与垂向23.1712.6735.84230风化基岩含水层复合微涌水92.6537.66130.31

为了进一步分析导高对含水层涌水量的影响规律,分别模拟了该煤层开采导高在50~250 m条件下含水层总涌水量(图7),结果显示,导高越大,总涌水量越大,当导高小于180 m时,导水裂隙发育至基岩含水层内部,尚未沟通风化基岩含水层,含水层涌水量增加幅度不大;当导高大于180 m时,由于导水裂隙揭露富水性较好的风化基岩含水层,导致含水层涌水量增加幅度较大,由此可见,通过限高、分层开采等采煤方法,抑制导水裂隙高度与覆岩强含水层的接触关系,是实现顶板水害防控与水资源协同保护的重要措施。

图7 不同导水裂隙高度下覆岩含水层涌水量曲线
Fig.7 Water inrush curve of aquifer groundwater under different height of water-conducting fractured zone

4 结 论

(1)通过分析榆神矿区主采煤层覆岩结构特征,将矿区主采煤层覆岩含(隔)水层划分为松散孔隙、基岩与风化裂隙、烧变岩孔洞裂隙4个含水层组,以及主、亚2个隔水保护土层。

(2)通过分析主采煤层采动导水裂隙与覆岩含(隔)水层组的空间组合关系,提出浅埋煤层侧向直接涌水、中深煤层侧向与垂向复合涌水、深部煤层复合隔水保护微涌水3种含水层涌水模式。

(3)采用COMSOL数值分析方法,分别以凉水井、小壕兔、曹家滩井田为例,定量模拟分析了3种模式涌水规律,其中浅浅埋煤层侧向直接流失型(凉水井井田)工作面顶部含水层被疏干,各含水层均为侧向涌水,涌水总量为47 m3/h;深埋煤层侧向与垂向复合隔水保护弱涌水型(小壕兔1号井田),含水层涌水总量为21.87 m3/h,以基岩含水层侧向涌水为主;中深煤层侧向与垂向复合微涌水型(曹家滩井田),煤层分层开采条件下导水裂隙发育至基岩含水层内部,含水层侧向涌水量为23.17 m3/h,垂向涌水量为12.67 m3/h;一次采全高条件下由于导水裂隙发育至风化基岩含水层底部,垂向越流加剧,涌水总量增至131 m3/h;可见通过限高、分层开采抑制导水裂隙发育高度是实现顶板水害防控与水资源协同保护的重要措施。

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Analysis of overlying aquifer water inrush above mining seam in Yushen mining area

ZHAO Chunhu1,2,JIN Dewu1,2,LI Zhixue3,SHEN Xiaolong4,WANG Hao1,2,WANG Shidong1,2, XU Feng1,2,WANG Qiangmin1,2

(1.Xian Research Institute of China Coal Technology & Engineering Group CorpXian 710054,China; 2.Shaanxi Key Laboratory of Prevention and Control Technology for Coal Mine Water Hazard,Xian 710177,China; 3.Shaanxi Investment Group Co.,Ltd.,Xian 710061,China; 4.Shaanxi Coalfield Geology Investigation Research Institute Co.,Ltd.,Xian 710021,China)

Abstract:Yushen mining area is an important part of the coal base in Northern Shaanxi.Aiming at the problems of insufficient research on water inrush of aquifer above the coal seam being mined in Yushen mining area,the overlying strata of the coal seam being mined is divided into four aquifer groups:loose pore,bedrock and weathering fissure,cave-fissure aquifer in burnt rock,as well as the main and sub-2 water-proof soil layers according to the typical geological and hydrogeological structure characteristics of the mining area,Three types of aquifer water inrush modes are proposed and named as “shallow lateral direct water inrush mode”,“medium-deep lateral and vertical combined water inrush mode” and “deep-buried lateral and vertical weak water inrush mode” respectively according to the water inrush characteristics of aquifers under different combinations of water-conducting fissure zone and aquifer groups.The water inrush analysis models of three coal mining modes on the scale of coal mining face are constructed,which shows that under the lateral direct loss type of shallow seam condition (Liangshuijing coal mine),the main mineable coal seam is No.4-2,because of the water-conducting fissures directly develop to loose aquifers,the top aquifer of the mining face is dried,the total water inrush is 47 m3/h,and the mining effect on groundwater flow field is significant.In the deep-buried composite water-proof protection micro-loss type (Xiaohaotu No.1 coal mine),the main mineable coal seam is No.1-2,the total loss of water in the aquifer is 21.87 m3/h,it is mainly in the form of lateral water inrush,although the water-conducting fissures develop into bedrock aquifers,the groundwater flow of the loose pore aquifer is basically unchanged under the protection of main and sub-soil layers.In the medium-deep lateral and vertical composite water inrush type (Caojiatan coal mine),the main mineable coal seam is No.2-2,and the average thickness of No.2-2 coal seam is about 11 m,water-conducting fissures develop to the interior of bedrock aquifer under the condition of stratified mining of coal seam which leads to a lateral water inrush of aquifer with 23.17 m3/h and a vertical water inrush with 12.67 m3/h,the groundwater flow of loose aquifer changes little.The total water inrush increases to 131 m3/h which has a great influence on the loose aquifers when the water-conducting fissures break through the sub-aquifer and develop to the bottom of the weathered bedrock aquifer under the condition of full mining height.In addition,the total amount of water inrush increases slightly with the increase of the height of the water-conducting fissures when the height of water-conducting fissure zone is less than 180 m and does not extend to the weathered bedrock aquifer.However,the water-conducting fissures expose weathered bedrock aquifers with better water-rich when the height of the water-conducting fissures is greater than 180 m,which leads to a larger increase in the water inrush of aquifers.It can be seen that it is an important measure to control the water inrush by restraining the contact relationship between the height of water conducting fracture and the overburden aquifer with significant water yield.The research results of this paper provide a scientific basis for the prevention and control of roof water disaster and the coordinated protection of water resources in the arid and semi-arid mining areas of Western China.

Key words:water preserved coal mining;aquifer;water inrush mode;water-conducting fracture;Yushen mining area

中图分类号:TD745

文献标志码:A

文章编号:0253-9993(2021)02-0523-11

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收稿日期:2020-04-26

修回日期:2020-09-18

责任编辑:钱小静

DOI:10.13225/j.cnki.jccs.2020.0713

基金项目:陕西省自然科学基础研究计划资助项目(2020JM-715);天地科技股份有限公司科技创新基金资助项目(2018-TD-MS069,2018-TD-QN052)

作者简介:赵春虎(1981—),男,陕西扶风人,研究员,博士。E-mail:zhaochunhu@cctegxian.com

引用格式:赵春虎,靳德武,李智学,等.陕北榆神矿区煤层开采顶板涌水规律分析[J].煤炭学报,2021,46(2):523-533.

ZHAO Chunhu,JIN Dewu,LI Zhixue,et al.Analysis of overlying aquifer water inrush above mining seam in Yushen mining area[J].Journal of China Coal Society,2021,46(2):523-533.