直眼掏槽方法的现场优化试验研究
隧道工程直眼掏槽的效果
隧道工程直眼掏槽的效果随着凿岩机械的发展，在隧道掘进施工中，已广泛使用了直眼掏槽爆破技术，使得工程质量、掘进进度、爆破效果相对于其它形式的掏槽的爆破效果有了明显的改善和提高。
直眼掏槽主要有三种形式：平行空孔炮眼掏槽、筒形掏槽、漏斗掏槽。
平行空孔炮眼掏槽，即爆破作用朝向一个或几个不装药的空孔炮眼方向。
筒形掏槽是通过向一个空眼顺序地起爆第一、第二及其它炮孔来完成扩大槽口面积。
漏斗掏槽即由向隧道工作面爆破的一个或几个完全装药的炮眼组成，与炮眼成直角的自由面爆破。
直眼掏槽，掘进进尺高，破碎块度好，在隧道直眼掏槽爆破中，值得注意的有：每米炮眼装药量，并不是炸药越多越好，随着炮孔直径的变化，每米装药量其实也是变化的，装药量与炮孔直径成正比，但在夹制作用比较大的工作面，过多的炸药量可能会引起爆破的困难。
殉爆，由于直眼掏槽炮眼比较多，如果岩石结构裂隙发育，会引起相邻炮孔的殉爆。
起爆顺序的影响，直眼掏槽用毫秒或秒差雷管起爆，都能达到比较满意的爆破效果，但是很多情况下，能发现炮眼内的炸药被邻近的炮眼爆破崩出来，不是炸药本身的问题，而是起爆顺序出现了问题，应该检查岩石结构面，看看哪些炮眼的起爆不利于邻近炮眼，哪些先起爆，哪些后起爆，重新进行布局。
钻眼偏差，凿岩机械与手工钻比的话，手工钻的钻研偏差可能要大的多，但是新的机械手没有使用习惯或者没有很好掌握凿岩机的操作时，钻研偏差也会很大。
钻眼偏差对爆破效果直接产品影响，根据统计3米孔深，一般偏差在1.9厘米/米，4米孔深，一般偏差2.0厘米/ 米，2米孔深，偏差在1.7厘米/米。
抛掷、破碎块度，一般来说，毫秒雷管的抛掷距离要大于秒差雷管，破碎块度也比较小，爆堆高度要低于秒差雷管。
因而在不同的条件下，选择毫秒雷管还是秒差雷管，需要根据实际情况。
在欧美的爆破资料中，对于直眼掏槽的爆破效果，尤其在掘进进尺方面，平均进尺率在90%以上，有的达到97%。
在散装炸药系统应用的现代，爆破效果会更好，有的直接就达到没有残眼，可谓是100%的炮孔利用率。
准直眼掏槽爆破新技术应用
第30卷第2期岩石力学与工程学报V ol.30 No.2 2011年2月Chinese Journal of Rock Mechanics and Engineering Feb.，2011岩巷掘进准直眼掏槽爆破新技术应用实例分析单仁亮，黄宝龙，高文蛟，朱永，郝先勇(中国矿业大学力学与建筑工程学院，北京100083)摘要：为了提高岩巷掘进速度，克服直眼掏槽和斜眼掏槽的不足，根据岩石爆破理论，提出一种新的掏槽方法——准直眼掏槽方式。
该掏槽方式突破传统掏槽设计，主掏槽眼稍微倾斜(准直眼)，槽底炮孔间距较大，次掏槽眼垂直于自由面。
与现有掏槽方式相比，该掏槽方式具有以下特点：准直眼孔底间距大，可杜绝穿孔现象；采用合理间隔时间进行分层分次爆破；中心辅助直眼与两侧对称的准直眼互相配合，结合直眼掏槽和斜眼掏槽各自的优点；形式简单，易操作；槽腔大，效率高，成本低。
基于爆生气体的准静态理论和岩石力学的极限平衡理论，分析准直眼掏槽槽腔形成过程。
为了优化准直眼掏槽参数，进行大量的现场掏槽试验，从而确定不同爆破条件下的准直眼掏槽炮孔的布置方式、深度、倾斜角度、间距、装药量和微差起爆间隔时间等技术参数。
施工中采取以长度定角度的方法可满足该掏槽方式对准直眼角度的严格要求。
实践表明，在煤矿岩巷掘进中使用准直眼掏槽方式，能够取得良好的爆破效果和显著的技术经济效益。
关键词：采矿工程；岩巷掘进；准直眼掏槽；爆破工程；实例分析中图分类号：TD 236 文献标识码：A 文章编号：1000–6915(2011)02–0224–09 CASE STUDIES OF NEW TECHNOLOGY APPLICATION OF QUASI-PARALLEL CUT BLASTING IN ROCK ROADWAY DRIV AGESHAN Renliang，HUANG Baolong，GAO Wenjiao，ZHU Yong，HAO Xianyong (School of Mechanics and civil engineering，China University of Mining and Technology，Beijing100083，China)Abstract：A new cutting method named quasi-parallel cutting method is proposed according to the rock blasting theory；and it helps to achieve the goal of rapid drivage for rock roadway by drilling and blasting and to overcome the deficiencies in parallel cutting and inclined-hole cutting. Quasi-parallel cutting method is a break through to the traditional cut blasting design. Main cutting holes(quasi-parallel holes) are slightly inclined；their distances at the bottom are long；and sub-cutting holes are perpendicular to the free face. Compared with current cutting methods，it has the following advantages：(1) It avoids the phenomenon of drilling holes crossing each other because of long distance at the bottom of quasi-parallel holes. (2) Slicing and stage blasting method is used at a reasonable interval time. (3) Straight sub-holes in the center and the symmetrical quasi-parallel holes cooperate with each other；it is a successful combination of parallel cutting method and inclined-hole cutting method. (4) The cutting form is very simple and easy to operate. (5) It can get large cavity with high efficiency and low-cost. Based on the quasi-static theory of blasting gas and the limit equilibrium theory of rock mechanics，the generation process of cavity has been analyzed. For the purpose of optimizing the quasi-parallel cutting parameters，a series of field tests are carried out；technical parameters of cutting holes including layout，depth，angle of inclination，spacing，charge and the interval time of short-delay blasting are obtained under different blasting conditions. Angle of quasi-parallel hole is determined by measuring length during construction，which can meet its accurate requirements. The test results show that the better blasting effect and obvious technical and economic benefits in coal rock drivage can be acquired by means of the quasi-parallel cutting method.Key words：mining engineering；rock roadway drivage；quasi-parallel cutting；blasting engineering；case studies收稿日期：2010–08–09；修回日期：2010–11–04作者简介：单仁亮(1964–)，男，博士，1987年毕业于中国矿业学院矿山建设工程专业，现任教授、博士生导师，主要从事岩土工程方面的教学与研究工作。
隧道掘进常用掏槽方式及参数合理性评价与分析
眼掏槽法。本文选择了其中最常用的 6 种掏槽方式予
以讨论，见图 1。确定某一施工条件下合理的掏槽
1
1
2
2
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500 200
2001 年 12 月 10 日收到初稿，2002 年 2 月 24 日收到修改稿。
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作者 东兆星 简介：男，35 岁， 1987 年毕业于中国矿业大学矿井建设专业，现为副教授、在职博士研究生，主要从事爆破理论和技术的科研与教
per-volume
2.9.4 掏槽孔利用率可靠性函数 u4 掏槽孔利用率一般为 0.7～0.85，当大于 0.85
时即为“很好”，当小于 0.7 时即视为不合理掏槽形 式。其可靠性函数曲线满足梯形分布(下限型)，由 下式表示：
⎧0
u4≤ 0.7
μ
A
(u4
)
=
⎪⎪ ⎨ ⎪
u4 − 0.7 0.85 − 0.7
第 22 卷 第 9 期 2003 年 9 月
岩石力学与工程学报 Chinese Journal of Rock Mechanics and Engineering
22(9)：1478～1482 Sep.，2003
隧道掘进常用掏槽方式及参数合理性评价与分析
东兆星 1 李佃平 1，2 李正龙 1，2 谢强珍 1，2 刘洪儒 2
掏槽效果的好坏又主要取决于掏槽方式及其参数。 因此，根据围岩地质情况和掘进面大小选择合理的
2 掏槽方式及其参数的优化
掏槽方式及其参数，是很重要的。
掏槽方式可以分为斜眼掏槽和直眼掏槽。目前， 2.1 评价掏槽方式的因素
在隧道掘进中常用有楔形掏槽(斜眼掏槽)或几种直
评价掏槽方式的效果要考虑到许多因素，其中，
坚硬岩层中井巷掘进采用直眼掏槽的研究
取 包含 冈子 ｋ＝２（近似 ９５％置信 慨弓焉），则扩展 不确
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定度 ：
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９ 结果
参 考文 献：
［１］国家质’髓 ｝支术监督 局 测最不确定度 与表示 ［Ｍ】北京：中围计 ＿｝诗｝¨版社，１９９９
，
［２】水 和 Ｊ发水监测 分忻 方法 ［Ｍ】北京 ｔｆ１围环境科学 出版 社，２００２
２ 掏槽 眼爆 破技 术参数选 择
决 定 掘 进 进 尺 的 关 键 是 掏 槽 眼 爆 破 。 掏 槽 眼 的 作 用 是 旨 先 在工 作面将 某一 部分岩石 破碎 并抛 出 ．在一 个爆 破 自南面 的基劬 上崩 出第二个 自南面 ．为其他炮 眼的爆 破创造 有利条 件 。要提 高炮 眼利用 葺夏，就 应 苗‘先选择 合理 的掏槽形式 和掏 槽 参数 。 ２．１掏槽 形 式
２５．ｏ０ ｍＬ的刻度吸 管 容皱允许 差 为士０．０３０ｍＬ．其 引 入
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７ 相对 合成标 准不确 定度
９．１根 据评 定结 果 ，样 品 中总磷 的浓度表 示为 ：
Ｃ ＝ ０．４Ｉ１士０．００７ｍｇ／Ｌ。
ＵＣ（ｃ）＝［Ｕｒｅｌ！（ｍ１）＋Ｕｒｅｌ （ｍ２）＋Ｕｒｅｌ （ｍ３）＋［ｕｒｅｌ！ｍ４）＋Ｕｒｅｌ （Ａ）＋
３ 技术 比较
在 同一巷 道采 取小 同 的掏槽 眼布 置形式 进行 技术 试验 ， 时爆 破效 果进 行技 术对 比。
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对提高矿井钻探进尺效率方法的探讨
2023年 6月下 世界有色金属135水文地质H ydrogeology对提高矿井钻探进尺效率方法的探讨刘艳杰（新汶矿业集团地质勘探有限责任公司，山东 新泰 ２７１２００）摘 要：矿产资源作为国家发展的重要资源之一，虽然在新能源发展的现在，战略价值有所下降，但仍然是不可缺少的能源之一。
因此矿产的开采是非常重要的，对于矿山企业来说，矿产开采效率是企业发展的重要因素之一。
现阶段在矿产开采的过程中，对于开采的技术和安全都有了更高的要求，开采的标准也越来越严格，钻探进尺技术是矿产开采重要的技术之一，本文就从影响钻探进尺效率因素的角度出发，对提高矿井钻探进尺效率方法进行简单的探讨。
关键词：矿井钻探；进尺效率；效率中图分类号：ＴＤ７４５ 文献标识码：Ａ 文章编号：１００２－５０６５（２０２３）１２－０１３５－３Discussion on methods to improve the efficiency of mining drilling footageLIU Yan-jie（Ｘｉｎｗｅｎ Ｍｉｎｉｎｇ Ｇｒｏｕｐ Ｇｅｏｌｏｇｉｃａｌ Ｅｘｐｌｏｒａｔｉｏｎ Ｃｏ．， Ｌｔｄ，Ｘｉｎｔａｉ ２７１２００，Ｃｈｉｎａ）Abstract: Ｃｏａｌ ｒｅｓｏｕｒｃｅｓ ａｓ ｏｎｅ ｏｆ ｔｈｅ ｉｍｐｏｒｔａｎｔ ｒｅｓｏｕｒｃｅｓ ｏｆ ｎａｔｉｏｎａｌ ｄｅｖｅｌｏｐｍｅｎｔ， ａｌｔｈｏｕｇｈ ｉｎ ｔｈｅ ｎｅｗ ｅｎｅｒｇｙ ｄｅｖｅｌｏｐｍｅｎｔ ｎｏｗ， ｔｈｅ ｓｔｒａｔｅｇｉｃ ｖａｌｕｅ ｈａｓ ｄｅｃｌｉｎｅｄ， ｂｕｔ ｉｔ ｉｓ ｓｔｉｌｌ ｏｎｅ ｏｆ ｔｈｅ ｉｎｄｉｓｐｅｎｓａｂｌｅ ｅｎｅｒｇｙ． Ｔｈｅｒｅｆｏｒｅ， ｃｏａｌ ｍｉｎｉｎｇ ｉｓ ｖｅｒｙ ｉｍｐｏｒｔａｎｔ， ｆｏｒ ｃｏａｌ ｅｎｔｅｒｐｒｉｓｅｓ， ｃｏａｌ ｍｉｎｉｎｇ ｅｆｆｉｃｉｅｎｃｙ ｉｓ ｏｎｅ ｏｆ ｔｈｅ ｉｍｐｏｒｔａｎｔ ｆａｃｔｏｒｓ ｏｆ ｅｎｔｅｒｐｒｉｓｅ ｄｅｖｅｌｏｐｍｅｎｔ． Ａｔ ｐｒｅｓｅｎｔ， ｉｎ ｔｈｅ ｐｒｏｃｅｓｓ ｏｆ ｃｏａｌ ｍｉｎｉｎｇ， ｔｈｅｒｅ ａｒｅ ｈｉｇｈｅｒ ｒｅｑｕｉｒｅｍｅｎｔｓ ｆｏｒ ｍｉｎｉｎｇ ｔｅｃｈｎｏｌｏｇｙ ａｎｄ ｓａｆｅｔｙ， ａｎｄ ｔｈｅ ｍｉｎｉｎｇ ｓｔａｎｄａｒｄｓ ａｒｅ ｂｅｃｏｍｉｎｇ ｍｏｒｅ ａｎｄ ｍｏｒｅ ｓｔｒｉｃｔ． Ｄｒｉｌｌｉｎｇ ｆｏｏｔａｇｅ ｔｅｃｈｎｏｌｏｇｙ ｉｓ ｏｎｅ ｏｆ ｔｈｅ ｍｏｓｔ ｉｍｐｏｒｔａｎｔ ｔｅｃｈｎｏｌｏｇｉｅｓ ｉｎ ｃｏａｌ ｍｉｎｉｎｇ． Ｔｈｉｓ ｐａｐｅｒ ｓｉｍｐｌｙ ｄｉｓｃｕｓｓｅｓ ｔｈｅ ｍｅｔｈｏｄｓ ｏｆ ｉｍｐｒｏｖｉｎｇ ｄｒｉｌｌｉｎｇ ｆｏｏｔａｇｅ ｅｆｆｉｃｉｅｎｃｙ ｉｎ ｃｏａｌ ｍｉｎｅ ｆｒｏｍ ｔｈｅ ａｎｇｌｅ ｏｆ ｉｎｆｌｕｅｎｃｉｎｇ ｆａｃｔｏｒｓ ｏｆ ｄｒｉｌｌｉｎｇ ｆｏｏｔａｇｅ ｅｆｆｉｃｉｅｎｃｙKeywords: ｍｉｎｅ ｄｒｉｌｌｉｎｇ； Ｆｏｏｔａｇｅ ｅｆｆｉｃｉｅｎｃｙ； ｅｆｆｉｃｉｅｎｃｙ收稿日期：２０２３－０４作者简介：刘艳杰，男，山东新泰人，生于１９８７年，大学，工程师，研究方向：煤炭地质测量、工程测量。
浅谈直眼掏槽技术在岩巷掘进中的应用
（ １ ） 合理确定直眼掏槽技术参数 ， 提高爆破效果
直 眼 掏槽 技 术 有 严格 的要 求 ， 只 有 科 学 地 制 定 有 关 技 术参数 ， 才 能 发 挥 最 佳 的爆 破 效 果 。根 据 有 关 资 料 和 现 场 实验 ， 生 产 股 总 结 出 一 套适 用 于 本 矿 岩 巷 掘 进 的 直 眼 掏 槽
１ ） 采 用 常 规 斜 眼掏 槽 ， 爆破效果不好 ， 循环进尺低 ；
２ ） 工 人 素质 低 ， 操作技 能水平不 高 ， 钻眼 、 爆 破 不 按 有 关技术参 数 ， 出现少 打眼 、 乱 打眼 ， 炮 泥 封 口不 足 等 ， 偷 懒
省 工 现 象 。导 致 钻 眼 质 量 差 ， 炮 眼利 用 率 低 ， 施 工 质 量 不 能 达 到 有 关 技术 要 求 。
ａ ｄ ｖ ａ ｎ ｃ ｅ ｐｅ ｒ ｒ ｏ ｕ ｎ ｄ ａ ｎｄ ｄ ｒ ｉ ｖ ｉ ｎ ｇ ｌ ｅ ｖ ｅ ｌ ｉ ｎ ｐ ｒ ｏ ｄ ｕ ｃ ｔ ｉ ｏ ｎ ｐ ｒ ａ ｃ ｔ ｉ ｃ ｅ ． Ｋｅ ｙ ｗｏ ｒ ｄ ｓ ：ｄ ｒ ｉ ｖ ｉ ｎ ｇ ｌ ｅ ｖｅ ｌ ；ｐ ａ ｒ ａ ｌ ｌ ｅ ｌ ｃ ｕ ｔ ｔ ｉ ｎｇ ｔ ｅ ｃ ｈ ｎ ｏ ｌ ｏ ｇ ｙ
ＬＵ Ｏ Ｊ ｉ ｌ ｏ ｎｇ
（ Ｚ ｈ ａ ｎ ｇ ｐ ｉ ｎ ｇ Ｃ ｏ ａ ｌ Ｉ ｎ ｄ ｕ ｓ ｔ ｒ ｙ Ｃ ｏ ． ，Ｚ ｈ ａ ｎ ｇ ｐ ｉ ｎ ｇ ，Ｆ ｕ ｉ ｉ ａ ｎ ３ ６ ４ ４ ０ ３ ）
Ａｂ ｓ ｔ ｒ ａ ｃ ｔ ： Ａｉ ｍｉ ｎ ｇ ａ ｔ ｔ ｈ ｅ ｐ ｒ ｏ ｂ ｌ ｅ ｍｓ ｏ ｆ ｌ ｏ ｗ ａ ｄ ｖ ａ ｎ ｃ ｅ ｐ ｅ ｒ ｒ ｏ ｕ ｎ ｄ ａ ｎｄ ｄ ｒ ｉ ｖ ｉ ｎ ｇ ｌ ｅ ｖ ｅ ｌ ｉ ｎ ｒ ｏ ｃ ｋ ｒ ｏ ａ ｄ ｗａ ｙ ｄ ｒ ｉ ｖ ｉ ｎ ｇ ｉ ｎ Ｄａ ｙ ａ ｏ
利用直眼掏槽技术提高掘进单进水平论文
利用直眼掏槽技术提高掘进单进水平【摘要】概述了直眼掏槽技术的作法及影响因素。
【关键词】直眼掏槽；光面爆破0.工程概况灵泉煤矿508队施工的五采区集中皮带道，担负着全矿改造运输系统，减少运输环节的重任，巷道掘进断面11.0平方米，净断面9.41平方米，巷道掘进宽3.6米，高3米，返上施工断480米，采用锚喷支护，巷道坡度为23度28分，巷道全岩掘进，施工工艺为凿岩机湿式凿岩，光面爆破，耙斗机装岩，一吨矿车出渣，作业形式采用三八作业，顶底岩性为白砂岩，且整体性好，如何实现优质快速高效迅速完成矿务工程，是摆在我们这些掘进人面前的一大课题。
我们在加强管理的同时，在充分调查的基础上，依靠技术手段，依托直眼掏槽爆破效率高等特点，采用1.8米中深孔光面爆破，并根据岩性调整直眼掏槽的形式和技术参数，增加了循环进尺，月平均进尺在62米以上，较原斜掏月平均进尺40米，提高月进尺22米，因中加快了掘进速度，缩短了工期，为我矿增产奠定了基础。
爆破参数1.采用的打眼机具及爆破材料打眼机具：7655型风动凿岩机。
爆破材料：炸药选用三号煤矿许用乳化炸药雷管选用8#金属壳毫秒电雷管。
封泥采用粘土炮泥，周边眼封泥长度不小于0.3米，其它眼封泥长度不小于0.5米。
2.掏槽眼形式及布置形式（附图）五采集中皮带道炮眼布置图（1）眼深：掏槽眼深确定为2米，其它炮眼深确定为1.8米。
（2）掏槽眼形式：五星式直眼掏槽。
中心眼布置在巷道中央偏下，属装药眼，以中心眼为中心，在半径为l00mm的圆周轮廓线上打4-5个眼，不装药，为空眼，做为自由面。
在半径为400mm的圆周轮廓线上打4个加强掏槽眼，进行装药。
这种直眼掏槽的特点：一是从直眼掏槽原理上讲，是利用空眼作为自由面，中心眼起爆后，4～5个空眼可加大自由面及中心眼起爆后碎胀空间。
岩石偏软时，打5个空眼；岩石偏硬时打4个空眼。
二是在周围再打4个装药眼，就可以解决直眼掏槽所造成掏槽腔槽体积小的问题。
立井深孔直眼分段掏槽改善爆破块度机理的分析与研究
／ ， ／
及 在岩石 中的残余应 力 改善岩 石 的破 碎效果 。 由于应 力 波在 自由 面上 的反 射 作 用 ， 分 段装 上
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１ 分段掏槽改善破碎块度 机理
直眼分 段掏槽 爆破 的实 质是对 槽孔 实施 分段装 药， 中间填 隔一定 长度 的炮 泥 ， 自上而下顺 序微 差起
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爆 破 块 度 机 理 的 分 析 与 研 究
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摘
要： 利用微差爆破破岩理论 ， 对分段掏槽 改善破碎块 度的机理 进行 了分 析 ， 后结合单孔 爆破漏 斗试 最
直眼掏槽在隧洞软岩施工中的应用及爆破参数优化
直眼掏槽在隧洞软岩施工 中的应用及爆破参数优化
李文涛‘张 颖2 ，
( 1. 辽宁省汤河水库管理局， 辽阳 111000 ; 2. 长春市希望建筑工程监理有限公司， 长春 130012)
摘 要: 引细入汤工程隧洞出口岩段长度 2 293m 为 二云片岩， 强度较低， 属较软岩。施工中 爆破效果较 差， 欠挖补炮， 进度缓慢。经过改变掏槽方式及对爆 破参数的优化调整， 基本达到了设计和进度要求， 保 证 了进度和质量。 关键词: 隧洞;爆破参数; 直眼掏槽; 调整; 光面爆破 中图分类号 : U455 .6 文献标识码 : A
确定掏槽眼间距为 20cm， 中空眼直径为 60mma 周边孔 :按照设计要求采用新奥法施工 ， 为保护 围岩少受扰动 ， 必须采取光 面爆破。光面爆破参数 结合 前 期 施 工 的 经 验 ， 定 周 边 孔 间 距 E 为 确
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1 爆破参数的初选与存在的问题
1.1 爆破参数的初选
由于引细人 汤工程 的开挖 洞径 较小 : 3 . 4m x
3 .3m(宽 x 高) ， 无法进行多台钻机同时钻孔， 司钻
空孔直眼掏槽爆破在地下厂房开挖中的应用探讨
４２ 试验参数与效果 ．
从试验结果看 出 ， 螺旋掏槽和加密桶形掏槽爆 破效果较好 ， 炮孔利用率分别达到 ８％ 、９ ， ５ ８ ％ 考虑
爆堆集 中在工作面附近 ， 有利于装岩 ， 中得到了 工程 广泛的应用。不过 ， 直孔掏槽也没有统一的格式 ， 为 了探求直孔掏槽的最佳布孔方式 ， 笔者结合狮子坪
电站地下厂房的爆破开挖 。 进行 了一些现场实际试
收稿 日 ： ０ — ９ ２ 期 ２ ６ ０ —１． ０ 作者简介 ： 牟遗忠 （９５ 。 ； 都： １６ 一） 男 成 四川 华 电杂 谷脑水 电开发有 限责任公司高级工程师．
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目前， 隧洞掘进爆破掏槽孔形式主要有斜孔掏 槽和直孔掏槽 ２ １ 种Ｌ 引。其 中， 直眼掏槽根据布孔方
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维普资讯
第 ２ 卷 第４ ３ 期
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直孔掏槽一次成井技术中的掏槽参数优化
Trans.Nonferrous Met.Soc.China28(2018)1413−1423Cutting parameter optimization forone-step shaft excavation technique based on parallel cutting methodQi-yue LI1,Kai LIU1,Xi-bing LI1,Ze-wei WANG1,Lei WENG21.School of Resources and Safety Engineering,Central South University,Changsha410083,China;2.School of Civil Engineering,Wuhan University,Wuhan430072,ChinaReceived27March2017;accepted28December2017Abstract:The outcome of the cutting blasting in a one-step shaft excavation is heavily related to the cutting parameters used for parallel cutting method.In this study,the relationships between the cutting parameters(such as the hole spacing L and the empty hole diameter D)and damage zones were investigated by numerical simulation.A damage state indexγwas introduced and used to characterize the crushing and crack damage zones through a user-defined subroutine.Two indices,i.e.,η1andη2that can reflect the cutting performance,were also introduced.The simulation results indicate that an optimal value of L can be obtained so that theη1 andη2can reach their optimal states for the best cutting performance.A larger D results in better cutting performance when the L value maintains its best.In addition,the influences of the loading rate and the in-situ stress on the cutting performance were investigated.It is found that an explosive with a high loading rate is suit for cutting blasting.The propagation direction and the length of the tensile cracks are affected by the direction and the magnitude of the maximum principal stress.Key words:shaft excavation;prime cutting blasting;numerical analysis;cutting parameter optimization;loading rate1IntroductionShaft excavation has been widely applied in the development of underground mines and civil engineering[1−3].SHATERPOUR-MAMAGHANI and BILGIN[4]described the difficulty and importance of shaft excavation in mining and civil engineering,and VENKATESH et al[5]described the application of shaft excavation in hydroelectric engineering.There are some traditional shaft excavation methods,such as ladder,cage raise and Alimak raising methods.However,these methods are gradually becoming obsolete due to low efficiency and poor working conditions.One-step shaft excavation technique based on parallel cutting has been developed in shaft excavation engineering due to its high efficiency,safety and low cost thanks to the rapid development of large-scale drilling equipment[6]. Whereas,there are still some difficult issues to be solved before it can be widely used,such as the determination of blasting parameters and the high degree of constriction or fixation for burden rock[7].The formation of cut cavity is an important step in one-step shaft excavation.To ensure a satisfactory cavity, the blasting parameters including the cutting model,the empty hole diameter,the hole spacing and the dimensions of shaft section,should be properly determined.To date,few studies have been seen concerning on the blasting parameters quantification for one-step shaft excavation[8,9].Fortunately,the relatively abundant studies of cutting blasting for tunnel excavation provide useful guidelines for the development of one-step shaft excavation[10−13].ZARE and BRULAND[7]compared the design features between NTNU(Nonwegian University of Science and Technology)mode and Swedish mode.SOROUSH et al[14]noted that the diameter of the charging hole and the size of the tunnel section were the most critical blasting parameters in tunnel excavation.QIAO[15] built a mechanical model of the initiation delay time for parallel cut blasting by analyzing the two-phase fluid that was composed of broken rock pieces and explosion gases. Compared to tunnel excavation(with a depth of3−4m), the single excavation depth of a shaft(10−50m)is much longer,which increases the difficulty in implementing this technology.Therefore,it is of great importance toFoundation item:Projects(2016YFC0600706,2016YFC0600802)supported by the National Key Research and Development Program of China;Project (2017zzts186)supported by Cultivating Excellent Doctors of Central South University,ChinaCorresponding author:Kai LIU;Tel:+86-151********;E-mail:lkeason@DOI:10.1016/S1003-6326(18)64780-6Qi-yue LI,et al/Trans.Nonferrous Met.Soc.China28(2018)1413−1423 1414study the optimization of cutting blasting parameters in one-step shaft excavation.In the process of cutting blasting,it is crucial to determine the parameters of prime cutting blasting, where the empty holes are used as free surface and swelling space.Therefore,the size of the empty holes and the hole spacing between the prime cutting hole and the empty hole become the key factors[6].In this study, to study the changes in the damage zone of prime cutting at different empty hole diameters and hole spacings,25 numerical models of prime cutting blasting were built by ABAQUS.Two indices,i.e.,the blasting energy utilization and the blasting energy agglutination,were defined to analyze the relationship between the prime cutting parameters and the blasting effect.The effects of loading rate and anisotropy of high situ stresses on prime cutting blasting performance and blasting induced damage zones were evaluated.2One-step shaft excavation techniqueThe model of parallel cutting with four empty holes was used to fragment rock because it can provide a large swelling space for subsequent cutting holes.The blasting process of prime cutting hole is shown in Fig.1.Upon the initiation of the prime cutting hole,both a shockwave and high pressure are produced in the borehole,as shown in Fig.1(a).Owing to the small burden between the empty holes and the prime cutting hole in the cutting pattern,the shockwave induces a strong reflected tensile wave at the interface of the borehole wall when it arrives at the wall of the empty holes.Once the dynamic tensile stress is higher than the rock tensile strength,spalling may be induced at periphery of the empty holes wall,as shown in Fig.1(d).Radial cracks will form through the rock between the empty hole and prime cutting hole when the hole spacing is appropriate.The burden rock that is full of cracks is broken and then thrown out of the cavity by the static pressure effect of the detonation gas, as shown in Fig.1(e).As the subsequent cutting hole blasting progresses in a prescribed order,the cavity is gradually expanded.The above demonstration shows that the key factors for good cutting performance are the appropriate hole spacing,which creates a damaged zone through the burden between the empty holes and the prime cutting hole,meanwhile the diameter of the empty holes,which should not only meet the requirements of swelling space but also make full use of the reflected tensile wave energy.3Numerical simulation method3.1Dynamic material model of rock massMany brittle materials such as rock,ceramics and concrete have physical properties that are sensitive to strain rate.To obtain the relation of rock or rock-like material properties with different strain rates, researchers have conducted a large number of laboratory experiments[16,17].LI et al[18]used a splitHopkinson Fig.1Blasting process of prime cutting hole:(a)Prime cutting hole initiation;(b)Crushed zone formed;(c)Radial cracks expanded;(d)Spalling;(e)Burden rock broken completelyQi-yue LI,et al/Trans.Nonferrous Met.Soc.China 28(2018)1413−14231415pressure bar (SHPB)system to study the dynamic behaviors of red sandstone,marble and granite and found that the relationship between dynamic compressive strength and strain rate may be expressed using an exponential equation as follows:1/3cd C = σε(1)where σcd is the dynamic compressive strength of therock material, εis the loading strain rate,and C is a real constant for granite rock under a loading strain rate between 20and 60s −1.Here,C is found to be 64.9[19].The relationship between the dynamic compressive strength and the strain rate for brittle material,such as rock and concrete,is generally obtained in exponential or logarithmic form according to previous research [20−22].In this paper,an exponential formula (see Eq.(2))is used to represent the relation between the dynamic compressive strength and the strain rate:1/3cd cs 0.4= σσε(2)where σcs is the static compressive strength of rock.Because the strain rates of rock adjacent to the charge hole wall can reach 103−105s −1[23],in this paper,the average strain rate of 1×104s −1[24]is used to calculate the σcd in Eq.(2).Table 1summarizes the typical static mechanical properties of intact granite [25].Because in this study Mohr−Coulomb failure criterion is used to do most dynamic analyses in ABAQUS,some rock mass properties such as cohesion and the internal friction angle must be calculated.Table 2gives the dynamic mechanical properties of granite rock mass used in numerical analysis based on the Hoek−Brown criterion [26,27]when the geological strength index (GSI)is set to be 87.A GSI value of 87represents the intact rock mass with few initial cracks and rock joints.This value is chosen considering the explosive energyTable 1Static mechanical properties of intact granite (Granite Bukit Timah (Singapare Zhao 1996))σci /MPa E i /GPa υρ/(kg·m −3)σtB /MPam i(σci )dyn /MPa (E i )dyn /GPa 186840.25261011.115.31600114σci is unconfined compressive strength;E i is deformation modulus;υis Poisson ratio;ρis density;σtB is Brazilian tensile strength;m i is Hoek−Brown strength parameter;(σci )dyn is dynamic uncomfined compressive strength;(E i )dyn is dynamic deformation modulusTable 2Dynamic mechanical properties of granite mass with GIS value of 87(Granite Bukit Timah (Singapare Zhao 1996))E m /GPa σtm /MPa c m /MPa (φm )dyn /(°)107.2639.17183.5944.67E m is rock mass deformation modulus;σtm is rock mass tensile strength;c m is cohesion;(φm )dyn is internal friction angleused for breaking rock and serious explosive energy dissipation in the fragmentized rock mass.This selection does not specify any real conditions.3.2Blasting dynamic loadTo simulate prime cutting hole blasting,an appropriate explosion pressure wave should be loaded on the borehole wall.There are three methods for approximating the explosive pressure profile [28]:1)direct input of dynamic pressure as a function of time,2)equation-of-state (EOS)and 3)pressure-decay functions.The Gaussian function and triangular load function are used to obtain the approximate measured dynamic-pulse load.These procedures,however,are not close to the physical characteristics of the dynamic load and thus carry no physical meaning.The EOS describes material behavior under a very high-rate loading condition and the the equation is associated with different material quantities as a single function,regardless of the prior history of deformation.The parameters of the EOS for a detonation process may be considered incorrectly,leading to a lower accuracy of the EOS.Although decay functions have been studied for decades,most blasting applications use pressure-decay functions that replicate the exact waveform.In this study,a general form of the pressure function of explosion pressure is expressed as follows [29]:0(e e )t t P P --=-αβ(3)where P is the pressure at time t ,P 0is the peak pressure of the loading,and αand βare constants.To make the rising and decaying processes of the pressure wave more intuitive and convenient,two constants,i.e.,t 0=1ln-ββααand 001/(e e )t t --=-αβξ,are defined.When the value of P reaches the peak point P 0at t =t 0,Eq.(3)may be rewritten as 0(e e )t t P P --=-αβξ(4)The amplitude and duration of the pressure wave are determined by the explosive type and borehole size.In this paper,t 0is set to be 5μs,and P 0is set to be 1.6GPa,based on the performance parameters of the ANFO explosive [24].The pressure−time history used for numerical simulation is shown in Fig.2.3.3Numerical modelA 3D model,with an overall size of 12m ×4m ×4m (depth ×length ×width),was established in the code.Firstly,a prime cutting hole,with a diameter of 70mm and a depth of 10m,was drilled in the center model,and four empty boreholes with an identical depth of 10m were created around the center borehole,as shown inQi-yue LI,et al/Trans.Nonferrous Met.Soc.China 28(2018)1413−14231416Fig.2Pressure−time history acting on prime cutting hole wallFig.3.To investigate the blasting effect of the primecutting hole under different empty hole parameters in one-step shaft excavation,the diameter of an empty hole (D )was selected as 130,160,190,220and 250mm,and the hole spacing (L )was selected as 260,290,320,350and 380mm.A total of 25experimental scenarios were designed using the orthogonal method and all of the scenarios satisfy the compensating space theory of Eq.(5)[30]:22()(1)/[()(1)]4L D d k D d k π=+++-(5)where L is the hole spacing between the prime hole and empty hole,d is the diameter of the prime cutting hole,D is the diameter of the empty hole and k is the rock swelling coefficient with the scope of [1.45,1.90][30].In the rock blasting field of numerical models,boundary conditions generally cause the reflection of outward propagating waves to back into the model and do not allow the necessary energy radiation.To avoid this phenomenon,non-reflection boundaries are set on the outer side except the free surface.In this study,hydrostatic stress conditions have been taken into account,considering a depth of 780m for general mine work.The average unit weight is 25.50kN/m 3for the rock mass,and the corresponding hydrostatic primary in-situ stress is calculated to be20MPa.Thus,the simulation process of prime cutting blasting involves two loading modes,i.e.,static in situ stress and dynamic stress wave,which is a coupled static and dynamic loading problem.The problem can be solved through implicit−explicit analysis in ABAQUS.Firstly,the static in situ stress conditions are added and calculated in implicit module and then the non-reflection boundary conditions are set and dynamic loading process is computed based on the static results in explicit module.3.4Rock mass failure modeKUTTER and FAIRHURST [31]proposed that there are crush zones,crack zones,and elastic zones from the blasting hole to a given distance when blasting in an infinite rock mass.In the first zone,the radial compressive stress generated from the shockwave exceeds the dynamic compressive strength of the surrounding rock,and the rock develops crush zones and,primarily,compression and shear failure (also called a shear failure zone).In the second zone,shockwaves expend a huge amount of energy in the process of crush zone formation and attenuate to a compression stress wave that cannot crush the rock mass.The compression wave pushes rock in an outward radial motion and produces radial tensile cracks due to hoop tensile stress to form a crack zone (also called a tensile failure zone).To distinguish the damage zone in prime cutting blasting,a rock mass fracture degree index is defined by a field variable-vusdfld in the ABAQUS software called the damage state index γ:eqp max eqp eqp eqp t 0, 0(), 1, 0f f =⎧⎪=++=⎨>⎪⎩εσγεεεσ(6)where σmax is the maximum principal stress in history,σt is the dynamic tensile strength of the rock mass,εeqp is the equivalent plastic strain,and γis the rock damage state in the process of blasting,where 0≤γ<1is the elastic zone,γ=1is the tensile failure zone,and γ>1is the shear failure zone.Fig.3Prime cutting blasting model geometry and boundary conditionsQi-yue LI,et al/Trans.Nonferrous Met.Soc.China 28(2018)1413−14231417To evaluate the prime cutting hole blasting effect of different schemes,two indices,η1and η2,are defined by112S S =η,122R R =η(7)where S 1is the break area of prime cutting blasting under ideal conditions [6],S 2is the tensile failure zone area,R 1is the tensile failure zone radius of prime cutting blasting,and R 2is the tensile failure zone radius of single hole blasting.The parameters are illustrated in Fig.4.We can divide the energy consumption of a shock wave into four parts as follows:E w =E s +E t +E r +E e(8)where E w is the total energy shock wave carried,E s is the energy spent in the creation of the shear failure zone,E t is the energy spent in the creation of the tensile failure zone,E r is the energy reflected from the empty holes wall,and E e is the energy spent in the vibration of the elastic zone.The blasting energy is radially distributed in the shear failure zone,the tensile failure zone and the elastic zone when single hole blasting occurs in a rock mass,as shown in Fig.4(a).The blasting energy will be reflected when the compressive stress wave propagates to the walls of empty holes and reflects as a tensile stress wave,as shown in Fig.4(b).The value of reflective energy depends on the parameters of the empty hole.Therefore,for η1,the closer the value to 1is,the more the blasting energy is used for cutting cavity,thus a better result is obtained with the increase of η1.In contrast,for η2,the closer the value to 0is,the greater the concentration of blasting energy is,so the value of η2should be as small as possible for cutting.4Simulation results4.1Damaged zone formation processes on primecutting blastingFigure 5shows the damaged zone formationprocesses of prime cutting blasting.It can be seen from Fig.5(a)that the shock waves with sufficient compressive strength produce compression−shear damage around the prime cutting hole.The shear failure zone reaches the maximum when t =20μs,and then there are no dramatic changes for the zone after that time.As shown in Fig.5(b),the shock wave expends a huge amount of energy in the shear failure zone and rapidly attenuates to stress waves producing tensile damage due to hoop tensile stress.As the stress waves propagate to the walls of empty holes,some of the compressive waves change to tensile waves due to reflection on the free surface,as shown in Figs.5(c)and (d).The remaining stress waves continue to propagate through the rock mass between the empty holes.The tensile damage zone extends to the place where the hoop tensile stress is less than the dynamic tensile strength of the rock mass,as presented in Fig.5(e).When stress wave fronts are encountered behind the empty holes,the hoop tensile stress increases in the superposition zone of stress waves,and when it exceeds the dynamic tensile strength of the rock mass,a tensile failure zone occurs behind the wall of empty holes,as shown in Fig.5(f).In order to avoid the influence of free surface,the section of shaft is chosen to be 2m below the free surface.The numerical simulation results for the shear failure zone and tensile failure zone distribution under 25different schemes are shown in Fig.6.It can be seen that the size of the shear failure zone is independent of the parameters D and L .The outward expansion of the tensile failure zone decreases with a decrease in L ,whereas the size of the tensile failure zone behind the empty holes decreases with an increase in D .The reason for this phenomenon is that with an increase in the diameter of empty holes,the reflection of stress waves is increased,leading to a decrease in the hoop tensile stress in the superposition zone of stress waves.Fig.4Key parameters for representation of damaged zone:(a)Single hole blasting;(b)Prime cutting blasting;(c)Prime cutting blasting under ideal conditions1418Qi-yue LI,et al/Trans.Nonferrous Met.Soc.China28(2018)1413−1423Fig.5Damaged zone formation processes of prime cutting blasting:(a)t=20μs;(b)t=25μs;(c)t=35μs;(d)t=45μs;(e)t=60μs;(f)t=80μsFig.6Simulation results of25schemesQi-yue LI,et al/Trans.Nonferrous Met.Soc.China28(2018)1413−142314194.2Effect of hole spacing on prime cutting blastingAccording to Eq.(7),the25scheme values ofη1 andη2can be determined.Then,the curves of hole spacing L versusη1andη2can be obtained by using different empty hole diameters,as seen in Fig.7.It can be seen from Fig.7that the indicesη1andη2reach their optimal values at L=350mm.This is because when L is too small,the explosion pressure wave spreads out after passing through the prime cutting zone,leading to low energy utilization and concentration.Moreover,the rock between empty holes and the prime cutting hole may be excessively broken,and“regenerated rock”[6]may even be formed due to the small value of L.When L is too large,the prime cutting zone increases,and the areas of S1and S2increase respectively,with less in S1and more in S2,which also induces low energy utilization and concentration.Rock may be incompletely broken,which is consistent with the results of LI et al[6].The optimal value of the hole spacing L can be determined whenη1 andη2reach their optimal values based on numerical analysis.The optimal value of L is350mm for the25 schemes in this study.4.3Effect of empty hole diameter on prime cuttingblastingSimilarly,the indicesη1andη2for different empty hole diameters D and hole spacing L can be obtained,as seen in bining the results of Fig.6and Fig.8, the prime cutting blasting performance from the effect of empty hole diameter can be divided into three types,i.e., A(L=260mm),B(L=290,320mm),and C(L=350, 380mm)according to the shape of the tensile failure zone.Type A is called the diffusion type and is characterized by tensile cracks extending beyond the prime cutting zone.η1is independent of empty hole diameter D,whereasη2increases with an increasing D. Type C is called the cohesion type,where the tensile failure distributes in the prime cutting zone and no tensile cracks extend beyond the prime cutting zone.η1 increases with an increasing D,whereasη2decreases with an increasing D.Type B is a transitional type between types A and C,where only a few cracks extend outward,and bothη1andη2increase with an increasing D.This is probably influenced by the hole spacing:the hole spacing values of types A and B have notreached Fig.7Relationships betweenη1(a),η2(b)and hole spacing L at different DvaluesFig.8Relationships betweenη1(a),η2(b)and empty hole diameter D at different L valuesQi-yue LI,et al/Trans.Nonferrous Met.Soc.China28(2018)1413−1423 1420the optimal values,and most of the blasting energy diffuses from the prime cutting zone.However,the hole spacing of type C is optimal in the sense thatη1andη2 are in the optimal development direction with an increasing D.In this study,bothη1andη2are optimal when D=250mm.An optimal value exists for the hole spacing L based on the theory of compensating space premise.When L is less than the optimal value,“regenerated rock”may be formed in the cavity,the volume of the formed cavity is too small to provide adequate swelling space for subsequent hole blasting,and a large size of tensile damage zone is formed beyond the prime cutting zone that is disadvantage for subsequent hole blasting. Because of drilling deviation,drilling will be more difficult.When L is larger than the optimal value,the constriction of rock mass is increased,and an effective cavity cannot be formed.The effects of the empty hole diameter D on prime cutting blasting performance can be divided into three types by the action of hole spacing, andη1andη2are in the optimal direction of development with increasing D when the hole spacing reaches the optimal value.Therefore,to obtain the ideal effect of cutting blasting in one-step shaft excavation,a larger diameter of the empty hole should be chosen to create a free surface and swelling space,and the optimal value of hole spacing can then be determined.5Discussion5.1Blasting performance under varying loading rateconditionsThe mechanical properties of rock materials are affected by the loading rate.Previous studies showed that a higher loading rate tends to produce a larger shear failure zone followed by larger numbers of short fractures,whereas a lower loading rate results in a smaller shear failure zone with fewer and longer radial fractures[10,24].To verify the loading rate effect on the dynamic damage process in cutting blasting,different explosion pressure waves are used in the analyses.The model size is kept consistent with the above,and cutting parameters are chosen at the optimal values of D= 250mm and L=350mm.The peak pressure P0is kept at a constant of1.6GPa,the rising time t0is varied from5, 10,50to100μs.Figure9shows the pressure−time histories used for the numerical simulation.The numerical results are shown in Fig.10.When the loading rate of the explosion pressure wave is high (320MPa/μs),most of the energy is spent in creating the prime cutting zone,although there are a few cracks outside the prime cutting zone.When the loading rate decreases to a lower level(160MPa/μs),many short radial cracks appear behind the empty holes,and a part of the energy is spent outside the prime cutting zone. When the loading rate further decreases to32and 16MPa/μs,there are many longer radial cracks following the empty holes,and more energy is spent in the area behind empty holes.From these results,it can be seen that to improve the efficiency of a mining blasting operation,which is indicated by long radial cracks,the loading rate should be kept as low as possible.However, the loading rate should be as high as possible for the cutting blasting of tunneling and shaft excavation,which requires that the energy be spent in the prime cutting zone to avoid forming a damage zone outside the prime cutting zone.It is well understood that cutting blasting requires more unit explosive consumption than mining blastingdoes.Fig.9Different pressure−time histories used for numericalsimulationFig.10Simulation results of prime cutting blasting under different loading rates:(a)320MPa/μs;(b)160MPa/μs;(c)32MPa/μs;(d)16MPa/μsQi-yue LI,et al/Trans.Nonferrous Met.Soc.China28(2018)1413−14231421 5.2Blasting performance under varying in-situ stressconditionsIn deep underground mining,high in-situ stressesare usually present[32,33],which can affect the blastingoperations.High in-situ stresses may have two effects inblasting operations[24].The first effect is that the cracksthat are induced by in-situ stress may be extended orsuppressed by the blasting-induced stress field.Thesecond effect is an induced stress concentration aroundthe holes because of the in-situ stress leading to anasymmetrical fracture pattern under the action ofdifferent values of two principal stresses in the planenormal to the hole axis.To achieve a better cutting effect,it is important to study the crack propagation law ofcutting blasting under earth stress.Because the hole axisof shaft excavation is vertical,the vertical stress is keptconstant,and different anisotropic horizontal stresses areconsidered,the same model geometry and optimalcutting parameters(R=250mm,L=350mm,t0=5μs,P0=1.6GPa)from previous work are used in this study.In the present numerical simulation,the numerical modelis pre-loaded with different horizontal stresses and afixed vertical stress.The assigned stress values forprincipal in-situ stresses are given in Table3.The simulated fracture patterns of cutting blastingmodel with different anisotropic in-situ stress fields areshown in Fig.11,which clearly demonstrates that twoTable3Assigned stress values for principal in-situ stressesScheme No.Verticalstress/MPax horizontalstress/MPay horizontalstress/MPa1201010 2201020 3201030 4202010 5203010effects occur in cutting blasting under high anisotropic in-situ stresses.The second effect can even eliminate the influence of the first effect.Figure11(a)shows that tensile failures are radial when the horizontal stresses are equal,whereas the tensile failures are aligned in the direction of major horizontal principal stress axis;the larger the difference between two horizontal principal stresses is,the more obvious the phenomenon is.This is because the tensile stress perpendicular to the maximum horizontal principal stress axis is suppressed and the cracks tend to extend parallel to the maximum horizontal principal stress.However,it has been found that shear failure zones are not affected by anisotropic in-situ stresses.To increase the size of the cavity,the hole spacing L could be increased in the direction of the maximum horizontal principal stress.6Conclusions1)There is an optimal value of hole spacing L between the prime hole and empty holes.When the L is less than the optimal value,the rock between empty holes and the prime cutting hole are broken excessively and form“regenerated rock”.When L is greater than the optimal value,the rock will be broken incompletely.2)The effect of prime cutting will be better with an increase in the empty hole diameter D when the value of L is optimal.The effect of prime cutting is less with an increase in D when L does not reach the optimal value.3)Cutting blasting is suitable for using explosives with a high loading rate.For a high loading rate,there are few tensile cracks outside the prime cutting zone,and most of the energy is spent in the prime cutting zone.For a low loading rate,more radial cracks follow the empty holes,and more energy is spent in the area behind empty holes.Fig.11Simulation results of prime cutting blasting under anisotropic high in-situ stresses:(a)Scheme1;(b)Scheme2;(c)Scheme3;(d)Scheme4;(e)Scheme5。
大断面隧道直眼掏槽施工技术应用
Value Engineering50图1斜眼掏槽爆破掏槽孔布置图48050200引言本文以阿联酋铁路某隧道为背景，阐述隧道爆破中直眼掏槽爆破方案在工程中的实际应用。
文中援引隧道断面为125m 2，围岩种类主要以辉长岩为主，结构构造均匀，裂隙较少，岩石坚硬稳定，隧道开挖考虑采用全断面法进行。
为尽快完成施工任务，探索安全、稳定且进尺较大的爆破方案势在必行。
因此，本工程中采取的空孔直眼掏槽爆破的方案顺利解决了面临的这一难题。
1本隧道爆破方案的选择根据目前市场信息，隧道爆破施工总体可分为两大类：斜眼掏槽及直眼掏槽。
根据本工程岩石坚硬、稳定的特点，以及缩短施工工期的要求，加快隧道施工进度成了唯一的解决方式。
经两种爆破方式的对比可知，采取直眼掏槽方案为宜。
主要原因如下：1.1斜眼掏槽方案斜眼掏槽原理：采用倾斜于隧道轴线的爆破孔装药，使爆炸产生的冲击波强行剥离中心部位岩石，为后续岩石移动提供更多的自有面。
（图1）如图1所示，考虑到本工程中所涉及到的隧道岩石硬度高，完整性较好。
单层掏槽方式恐难以完全剥离掏槽区域岩石，因此现场施工中考虑采用双层掏槽以彻底剥离掏槽区，为其他爆破孔的爆破提供充足的自由面。
根据施工经验，斜眼掏槽的掏槽孔与自由面夹角为60°~70°掏槽效果为最佳。
本设计中，考虑掏槽孔最大的进尺深度为4.5m ，掏槽孔与掌子面夹角为64°，则第一排掏槽孔左右间距为4.8m ，孔底的最小抵抗线为40cm ；第二排掏槽孔左右间距则为5.3m 。
如图所示，如果继续增加左右两侧掏槽孔间距，则孔底的最小抵抗线增加，则同样导致掏槽区无法完全剥离；如果左右两侧掏槽孔间距减小，则掏槽孔与掌子面的夹角也随之减小，如此也容易导致掏槽区无法剥落的现象；且本隧道掌子面的最大宽度为13m ，若继续放大掏槽孔空口间距则会因两侧边墙影响，无法按照设计角度钻孔。
因此，本隧道的掏槽孔最大钻孔深度为4.5m ，掘进孔最大钻孔深度为4.3m ，考虑炮孔利用率为93%，则爆破深度为4m 。
大直径深孔中空眼直眼掏槽爆破技术应用研究
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掘进爆破 工 作 中 亟 待 解 决 的 主 要 问 题. 针 对 此 问
题,九里山矿在直 眼 掏 槽 爆 破 理 论 分 析 的 基 础 上,
采用数值模拟的方法探讨了大直径掏槽对 １６１２１ 底
抽巷围岩 力 学 性 质 的 影 响, 并 进 行 了 现 场 工 业 试
验,收集了相关爆破参数,进而提出了大直径深孔
煤矿岩巷掘进技术经过多年发展,主要有两种
作业方式:一种是钻爆法施工,另一种为机械掘进
施工.由于钻爆法施工具有良好的适用性,不受客
小断面特长隧道直眼十孔掏槽技术研究
小断面特长隧道直眼十孔掏槽技术研究发布时间：2022-11-13T02:53:08.546Z 来源：《建筑实践》2022年第13期第41卷作者：张凤喜[导读] 城市排污隧道因其断面小、洞身长，不利于平行施工和大型机械作业张凤喜中铁七局武汉工程有限公司摘要：城市排污隧道因其断面小、洞身长，不利于平行施工和大型机械作业，以丽水市污水输送干管隧道工程为例，针对施工中的钻爆法提出了切实可行的施工技术方案。
为加快城市小断面排污隧道的施工，减少人为因素，真正做到高功效，提效率、降成本的经济效益，有较好的借鉴作用。
关键词：丽水市污水输送干管工程；小断面隧道；直眼十孔掏槽1工程概况丽水市污水输送干管工程是丽水市五水共治工程也是丽水市重点民生工程，隧道正洞全长7228m，另有支洞756m，隧道围岩类别为Ⅱ、Ⅲ、Ⅳ、Ⅴ类，断面净宽为5.4m×4.6m，初期支护采用超前锚杆、径向锚杆、钢拱架、网喷砼等形式，衬砌为半圆拱分离直墙式衬砌，砼强度为C30. 2工程特点及方案的选定2.1工程特点(1)洞身长、工程量大、工期紧(2)隧道断面小，不利于大型机械作业，平行作业干扰大(3)隧道临近金丽温高铁大沃山隧道5828m，最近距离157m，临近金温货线1km以内1400m，下穿金丽温高速公路埋深38m，下穿中塘村、叶村等外围环境复杂。
（4)爆破影响范围广，振速控制较困难。
2.2方案比选(1)楔形（斜眼）掏槽：优点：掏槽眼数较少，相对应施工时间和装药量相对较少。
掏槽面积相对较大，适用于各种岩层及地质条件。
缺点：每循环进尺受断面尺寸限制，钻孔角度容易有偏差，影响掏槽效果，炮眼过深会造成较长残眼，炮眼利用率低，相对应造成单循环进尺不佳(2)直眼十孔掏槽：优点：大小断面都适用，小断面更优，炮眼受断面尺寸影响较小，单循环进尺可提高，对于所有围岩较适用，有利于光面爆破。
缺点：需要较多的炮眼数目，钻孔时间相对较长，掏槽眼要垂直掌子面，对工人钻眼操作要求高，经济性较好。
直眼掏槽爆破技术在小断面坑道中的应用
直眼掏槽爆破技术在小断面坑道中的应用发布时间：2021-07-27T15:00:34.087Z 来源：《基层建设》2021年第13期作者：花瑞[导读] 提要：济南市1029工程3#出入口断面小，地下坑地道爆破开挖存在进尺短，爆破效果差，靠近掌子面的开挖轮廓线经常出现欠挖现象。
中铁十四局集团第二工程有限公司山东省泰安市 123000提要：济南市1029工程3#出入口断面小，地下坑地道爆破开挖存在进尺短，爆破效果差，靠近掌子面的开挖轮廓线经常出现欠挖现象。
分析该现象产生的原因，并结合现场实际情况重新进行爆破设计。
通过实践证明，直眼掏槽技术在小断面坑地道施工中得到了预期的开挖效果，为今后小断面坑地道工程施工积累了经验。
关键词：直眼掏槽小断面坑地道爆破技术1.工程概述1.1工程概况某项目为地下坑道式工程，共设有三个出入口，3#坑地道开挖断面主要为3.4m×4.15m（宽×高）-3.4m×6.15m（宽×高）不等。
3#出入口承担施工任务长达773m，因竖井通风道位于3#坑地道，采用反开挖方案施工，因此3#出入口成为该工程施工的关键线路，该通道断面小，坑地道较长，施工难度大。
3#出入口地质剖面图显示，洞口段覆盖层为含碎石的粉质粘土，洞身为中风化石灰岩，灰色，隐晶质结构，中厚层状结构，主要为方解石组成，其次为白云石，围岩级别为IV级。
地下水不发育，主要靠大气降水补给，洞身开挖条件较好。
2.爆破方案的初选与优化2.1楔形掏槽由于3#出入口开挖断面较小：3.4×6.15m，无法进行多台钻机同时钻孔，洞口段围岩为V类，采用两台阶法施工。
前期按坑地道施工原则：小进尺、弱爆破。
开挖方案采用上下台阶施工，爆破开挖初选为楔形掏槽的爆破开挖方式，并制定上台阶爆破参数，根据规范不同围岩的装药系数进行计算，并结合现场爆破效果调整爆破参数至最优。
上台阶楔形掏槽爆破主要经济技术指标如下，设计钻孔深度1.7m，实际每循环进尺每循环进尺1.4m，炮孔利用率82.3％，开挖量22.20m³，炸药单耗2.39kg。