露天煤矿防渗墙截渗减排机制及工程应用研究(1).pdf

密 级 煤炭科学研究总院 博士学位论文 露天煤矿防渗墙截渗减排机制露天煤矿防渗墙截渗减排机制 及工程应用研究及工程应用研究 作者姓名 张 雁 学科专业 矿产普查与勘探 导师姓名 靳德武 研究员 完成时间 二○一八年六月十五日 万方数据 万方数据 China Coal Research Institute A dissertation for doctors degree Study on the mechanism and engineering application of seepage cutoff and drainage reduction of diaphragm wall in Open-pit coal mine Author’s Name Yan Zhang Speciality Mineral Prospecting and Exploration Supervisor Prof. Dewu Jin Finished time June 15th, 2018 万方数据 万方数据 煤炭科学研究总院学位论文原创声明 煤炭科学研究总院学位论文原创声明 本人郑重声明此处所提交的学位论文露天煤矿防渗墙截渗减排机制及 工程应用研究 ，是本人在导师指导下，在煤炭科学研究总院攻读博士学位期间 独立进行研究工作所取得的成果。据本人所知，论文中除已注明部分外不包含 他人已发表或撰写过的研究成果。对本文的研究工作做出重要贡献的个人和集 体，均已在文中以明确方式注明。本声明的法律结果将完全由本人承担。 作者签名 日期 年 月 日 煤炭科学研究总院学位论文使用授权书 煤炭科学研究总院学位论文使用授权书 露天煤矿防渗墙截渗减排机制及工程应用研究系本人在煤炭科学研究 总院攻读学位期间在导师指导下完成的学位论文。本论文的研究成果归煤炭科 学研究总院所有，本论文的研究内容不得以其他单位的名义发表。本人完全了 解煤炭科学研究总院关于保存、使用学位论文的规定，同意学校保留并向有关 部门送交论文的复印件和电子版本，允许论文被查阅和借阅，同意学校将论文 加入中国优秀博硕士学位论文全文数据库和编入中国知识资源总库 。本 人授权煤炭科学研究总院，可以采用影印、缩印或其他复制手段保存论文，可 以公布论文的全部或部分内容。 本学位论文属于（请在以下相应方框内打“√“; 保密□，在 年解密后适用本授权书 不保密□ 作者签名 日期 年 月 日 导师签名 日期 年 月 日 万方数据 万方数据 摘 要 i 摘 要 摘 要 露天煤矿在开采过程中需要对地下水进行疏降和控制， 常用的疏降与控制方 法有疏排降水和帷幕截流。 目前，我国在建和生产的露天煤矿均采用疏排降水方 法进行矿坑水疏降或疏干。 这种方式由于长时间大流量疏排地下水， 造成矿区周 边地下水位快速下降，引起植被枯死、井泉干枯、土地沙漠化等现象，对矿区自 然环境破坏严重，并导致矿区周边居民生活用水困难；同时，大量疏排地下水造 成地下水资源极大浪费， 且矿坑水的排放引起地表河流水质变差。露天煤矿在剥 离表土层及含水层水位疏降过程中易造成水土流失，引起边坡稳定性能下降， 给 疏排水工程和矿坑边坡维护与治理带来困难， 加之矿坑疏排水工程占用了大量的 人员与设备， 每年上千万元的疏排水费用为矿坑生产带来严重的经济负担，增加 了露天煤矿的生产成本。 为解决露天煤矿因疏排降水在矿坑“生态环境、生产安全、经济效益”等方 面带来的一系列问题，实现露天煤矿的绿色、安全、可持续发展，本文以扎尼河 露天煤矿为例， 通过采用防渗墙技术取代常规的疏排降水技术， 对露天煤矿渗流 补给通道进行帷幕截流，从根本上减少矿坑疏排水量，达到截渗减排的目的，主 要开展了以下研究 1、以矿区水文地质与工程地质条件为基础，结合防渗墙成墙工艺，提出露 天煤矿防渗墙建造应具备的必备条件、有利条件与应满足的经济条件；根据防渗 墙成墙工艺与墙体结构、 防渗墙平面展布形态和墙体底部是否进入稳定隔水地层， 将防渗墙从墙体结构、 平面展布形式、剖面形态等角度划分为桩孔压入式和沟槽 灌入式、直线型和弧线型、落底式和悬挂式等多种形式。 2、分析影响截渗减排效果的主控因素，以地下水渗流原理和复变函数理论 为基础，推导了通过防渗墙两侧与底部的绕流量计算公式和通过墙体自身的渗 流量计算公式。结果表明，绕流量与含水层渗透系数 K 和水头损失 H 呈正比， 与防渗墙长度 l 和深度 d 呈负相关关系；渗流量与防渗墙厚度 B 呈负相关关 系，与防渗墙渗透系数 K2呈正相关关系。 3、选择防渗墙连续长度为研究参数，采用室内渗流物理模型模拟了地下水 流场与渗流量随地下水水头高度和防渗墙连续长度的变化过程与规律， 拟合了渗 流量与防渗墙长度的函数关系， 建立截渗减排效果与防渗墙闭合度的关系。结果 表明， 截渗效果与防渗墙闭合度呈三次函数关系， 截渗减排效果随帷幕长度增加 而显著增加，进一步研究了防渗墙截渗减排机制。 4、通过建立数值模型，运用 MODFLOW 数值模拟软件开展防渗墙长度、深 度、 厚度与渗透系数等主控因素的变化对地下水流场和疏排水量的影响， 进而研 万方数据 摘 要 ii 究防渗墙不同参数对截渗减排效果的影响程度。 研究结果表明， 防渗墙长度越长， 将抽水中心水位降低至同一标高时所需抽水量越小， 抽水量减小的速度随防渗墙 长度的增加越来越快； 防渗墙深度对抽水量的影响主要取决于防渗墙底部所处的 地层， 落底式防渗墙截渗效果明显优于悬挂式；防渗墙厚度与抽水量的关系可用 二次多项式函数表示， 抽水量减小的速度随着防渗墙厚度增加而逐渐变缓；当防 渗墙渗透系数减小到 0.001m/d 以下时，继续减小渗透系数对截渗减排效果的影 响程度不大。研究结果完善并建立了防渗墙截渗减排机制。 5、以扎尼河露天煤矿为例，开展露天煤矿防渗墙建造工程试验，验证了露 天煤矿建造防渗墙的可行性， 采用流场观测法与抽水试验法检验了防渗墙的防渗 性能， 研究了防渗墙试验工程对地下水流场和矿坑疏排水量的控制作用， 验证了 截渗减排机制的合理性与有效性。 6、 建立水文地质概念模型与数值模型， 利用 MODFLOW 数值模拟软件模拟 工程试验结束后和墙体全部建成后的地下水流场与疏排水量， 进一步验证了截渗 减排机制并预测了截渗减排效果，依据研究成果建立墙体参数优化模型， 对扎尼 河露天煤矿防渗墙主体工程关键技术参数进行了设计和优化。 本文运用地下水渗流原理与复变函数理论推导了防渗墙绕流量和渗流量计 算公式，研究了防渗墙长度、深度、厚度和渗透系数等主控因素对截渗减排效果 的影响程度， 建立了露天煤矿防渗墙截渗减排机制。开展了露天煤矿防渗墙建造 工程试验，检验了截渗减排机制的合理性与有效性，预测了防渗墙全部建成后的 截渗减排效果，形成一套在露天煤矿建造防渗墙的理论研究、分析设计、工艺实 现及效果检验与预测的理论与方法， 为露天煤矿水害防治及水资源保护提供技术 支撑。 关键词关键词露天煤矿 防渗墙 截渗减排 机制 工程应用 万方数据 Abstract iii ABSTRACT In open-pit coal mine process, ground water level needs to be lowered and controlled. The commonly used s are water draining and curtain grouting. At present, the open-pit coal mines which under construction and production in China all adopt water draining to reduce or unwatering the water level. Because of the long period of big flow drainage, the water table surrounding the mining area is reduced rapidly, which cause the vegetation dying, the wells drying and the land desertification. The damage to the natural environment of the mining area is serious, and the residents living in the surrounding area have problem in domestic water. At the same time, the large amount of drainage groundwater causes great waste of groundwater resources, and the discharge of mine water causes the deterioration of surface river water quality. It is easy to cause water loss and soil erosion during the process of stripping the surface layer and aquifer, and the stability of the slope is reduced. All those bring difficulties to the drainage project and slope maintenance and management. In addition, the drainage project occupied a large number of manpower and equipment. The cost of drainage project in tens of millions of yuan every year, which brought serious economic burden and increased the production cost of the open-pit coal mine. In order to solve a series of problems such as “ecological environment, production safety and economic benefits“ caused by groundwater draining, and realize the green, safe and sustainable development of open-pit coal mine, in case of Zhanihe open-pit coal mine was studied as an example, diaphragm wall technology was used to replace the commonly used drainage technology, the seepage supply channel of open-pit coal mine is cut off by curtain grouting, and the drainage of mine is basically reduced. The following researches were mainly carried out 1.Based on the hydrogeology and engineering geological conditions of the mining area, combined with the construction process of the diaphragm wall, the necessary conditions, favorable conditions and economic conditions for the construction of the diaphragm wall of the open-pit coal mine were proposed. The diaphragm wall was divided into many s from the aspects of wall structure, plane distribution and section shape, such as pile hole pressing-type and groove pouring-type, linear-type and arc-type, bottom-type and suspension-type. 2.Main control factors which influence the seepage cutoff and drainage reduction effect were analyzed. Based on the groundwater seepage theory, by means of complex 万方数据 Abstract iv variable function theory, the ula for calculating the lateral flow rate of the two ends and the bottom of the diaphragm wall and the ula of the seepage flow through the body of the wall were derived. The results show that the lateral flow is in direct proportion to the aquifer permeable coefficient K and head loss H, has a negative correlation with the length l and depth d of the diaphragm wall; the seepage flow has a negative correlation with the thickness B and a positive correlation with seepage coefficient K2 of the diaphragm wall. 3.Indoor seepage physical model was established to simulate the process and law of groundwater flow field and seepage flow along with the changes of groundwater head and continuous length of diaphragm wall. The function relation between seepage flow and the length of the seepage wall was fitted, and the relationship between the effect of cut-off reduction and the closure degree of the diaphragm wall was established. The results show that there is a three function relationship between the seepage cutting effect and the diaphragm wall closing degree, the seepage cutting effect is significantly increased with the increase of the diaphragm wall lenghth. 4.Influences of the length, depth, thicknessand permeability coefficient of the diaphragm wall on groundwater flow field and volume of water drainage were studied based on the numerical simulation software MODFLOW. Simulation results ware consistent with the theoretical calculation results. The results show that the longer the diaphragm wall, the smaller the amount of water needed to lower the water level of the pumping center to the same level.The rate of water withdrawal decreases with the increase of diaphragm wall length.The influence of the depth of the seepage wall on the pumping amount mainly depends on the stratum at the bottom of the diaphragm wall, the relation between the thickness of the diaphragm wall and the pumping amount can be expressed by the two polynomial function. The speed of the pump water decrease gradually slows with the increase of the thickness of the diaphragm wall, when the permeability coefficient of the diaphragm wall decreases to less than 0.001m/d, The effect of decreasing the permeability coefficient on the seepage reduction is not significant. The research of seepage cutoff and drainage reduction mechanism was further improved. 5.Zhanihe open-pit coal mine was studied as an example to carray out the diaphragm wall construction test. The feasibility of diaphragm wall construction in open-pit coal mine was verified by 400 m long wall construction engineering test. Flow field observation and pumping test were used to test the seepage prevention 万方数据 Abstract v perance, analyze the control function of the diaphragm wall construction on the groundwater flow field. The drainage amount of the open-pit coal mine, the rationality and accuracy of the seepage cutoff and drainage reduction mechanism weres proved. 6. The effect of seepage cutoff and drainage reduction after the completion of the engineering test and the completion of the wall was simulated by the MODFLOW numerical simulation software. Based on the research results, the optimization model was set up, and the key technical parameters of the main body of the seepage proof wall in Zhanihe open-pit coal mine were designed and optimized. The purpose of this paper is to 1 Derive the calculation ula of the around flow and seepage flow of the diaphragm wall; 2 Study the influence degree of the main controlling factors of the diaphragm wall, and establish the mechanism of seepage cutoff and drainage reduction; 3 Carry out the diaphragm wall construction engineering test; 4 a set of diaphragm wall construction theory and of the analysis and design, construction technology and optimization, and effect test and forecast for open-pit coal mine. Technical support for open-pit coal mine of the water disasters prevention and water resources protection were provided. Keywords Open-pit coal mine; diaphragm wall; seepage cutoff and drainage reduction; mechanism; engineering application. 万方数据 万方数据 目 录 I 目 录 目 录 第 1 章 绪论 ...................................................................................... 1 1.1 问题的提出及研究意义............................................................................ 1 1.2 国内外研究现状........................................................................................ 2 1.2.1 防渗墙在国外的研究与应用现状 .................................................................. 2 1.2.2 防渗墙在国内的研究与应用现状 .................................................................. 4 1.2.3 帷幕工艺在国外露天煤矿的应用 .................................................................. 7 1.2.4 帷幕工艺在国内井工煤矿的应用 .................................................................. 8 1.3 防渗墙应用于我国露天煤矿存在的主要问题........................................ 8 1.4 研究内容与技术路线................................................................................ 9 1.4.1 研究内容 .......................................................................................................... 9 1.4.2 技术路线 ........................................................................................................ 10 第 2 章 露天煤矿防渗墙构建条件与类型 .................................... 12 2.1 露天煤矿防渗墙构建条件...................................................................... 12 2.1.1 必备条件 ........................................................................................................ 12 2.1.2 有利条件 ........................................................................................................ 13 2.1.3 经济条件 ........................................................................................................ 13 2.2 露天煤矿防渗墙构建类型...................................................................... 15 2.2.1 防渗墙结构类型 ............................................................................................ 15 2.2.2 平面构建类型 ................................................................................................ 17 2.2.3 剖面构建类型 ................................................................................................ 18 2.3 本章小结.................................................................................................. 20 第 3 章 防渗墙截渗减排理论计算 ................................................ 22 3.1 渗流连续方程.......................................................................................... 22 3.1.1 雷诺输运方程 ................................................................................................ 22 3.1.2 渗流连续方程 ................................................................................................ 24 3.1.3 流函数与势函数 ............................................................................................ 25 3.2 求解渗流问题的 Schwarz-Christoffel 变换 ........................................... 27 万方数据 目 录 II 3.3 影响截渗减排效果的主控因素分析...................................................... 28 3.4 墙体绕流量计算...................................................................................... 29 3.4.1 侧向绕流量计算 ............................................................................................ 30 3.4.2 底部绕流量计算 ............................................................................................ 36 3.5 墙体自身渗流量计算.............................................................................. 41 3.6 本章小结.................................................................................................. 43 第 4 章 防渗墙连续长度对截渗减排效果影响的物理模拟研究 44 4.1 渗流模型设计与构建.............................................................................. 44 4.1.1 渗流模型平台 ................................................................................................ 44 4.1.2 渗透材料选择 ................................................................................................ 46 4.2 补给水头高度对地下水流场和渗流量的影响模拟.............................. 47 4.2.1 补给水头高度对地下水流场的影响 ............................................................ 48 4.2.2 稳定渗流量与补给水头高度的关系 ............................................................ 51 4.2.3 渗流模型合理性验证 .................................................................................... 52 4.3 防渗墙连续长度对地下水流场与渗流量影响的模拟.......................... 53 4.3.1 地下水流场随阻水挡板长度变化的模拟 .................................................... 53 4.3.2 渗流量与过水断面关系模拟 ........................................................................ 62 4.3.3 防渗墙闭合度与截渗效果预测 .................................................................... 63 4.4 本章小结.................................................................................................. 64 第 5 章 防渗墙参数对截渗减排效果影响的数值模拟研究 ........ 66 5.1 模型构建.................................................................................................. 66 5.1.1 模型结构 ........................................................................................................ 66 5.1.2 边界条件与模型参数 .................................................................................... 67 5.1.3 求解方法 ...................................................................