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罗宾斯双护盾为尼泊尔首个掘进机项目开挖隧道
尼泊尔将在这个夏天迎接国内第一台的全断面隧道掘进机，一台直径5.06米的双护盾掘进机为巴瑞巴贝综合引水项目（BBDMP）开挖隧道。2017年7月这台罗宾斯掘进机在其工厂通过测试验收，现在正被运送到喜马拉雅山脉的南部克亚山脉（Siwalik Range）的工地，施工前，包括碎石路和敷设到农村饮用水井的开挖已完成，为掘进机的始发做好准备。
BBDMP是尼泊尔11个民族自豪感项目之一，这是尼泊尔政府批准的进一步发展主要农村国家的优先计划。该项目将在尼泊尔南部地区灌溉60,000公顷的土地，预计将惠及30,000户家庭。它将使用一个15米高的大坝，每秒从巴瑞河向巴贝河转移40立方米的水，水头150米，为周围的班克(Banke)和巴迪亚(Bardia)地区提供全年灌溉。该水还将用于水力发电，发电量为48兆瓦，每年有20亿尼泊尔卢比（月2,000万美元）惠及该国。
承包商中国海外工程集团有限公司尼泊尔分公司（中海工程尼泊尔分公司）负责建造这条引水隧道，并了解在恶劣地质条件下进行隧道施工所面临的挑战。“罗宾斯隧道掘进机的设计很好，尤其是双护盾隧道掘进机，” BBDMP项目经理胡天然说。西瓦利克山脉预计主要由砂岩、泥岩和砾岩组成，需要一个能够开挖挤压地质、不稳定岩石、可能高涌水和断层带的掘进机。隧道上方的最大埋深范围为820米。
由于喜马拉雅山年轻地质的挑战，在机器的设计中加入了困难的地质解决方案（DGS）。一个阶梯式的防护罩被设计用来穿过挤压地质。罗宾斯项目工程师Missy Isaman谈到了包含在掘进机中的DGS功能：“在后部有一个超前钻机，可以从撑靴盾14个位置伸出探测地质。我们在前面的护盾上也加了一些孔以便钻探。圆周上有8个孔用于人工钻探。还有6个孔位于前向上100度的护盾顶部。“她进一步指出，没有为前盾订购任何钻探设备，但现在更护盾中添加钻孔，以防后期在掘进中需要更全面的地质钻探。其他机器改装包括用于可能过度切割直径35 mm的量具切割，以及用于排水的前盾附加排水端口。
渣土清除将由渣土车完成。罗宾斯将提供现场服务，以支持前500米的机器安装、测试、调试和掘进。隧道将采用六角形预制混凝土段进行衬砌。
项目业主尼泊尔灌溉部（MOI）政府选择了一种掘进机，而不是传统的钻爆法，因为机械化采矿提供了更快的动员和推进速度。“为该项目选择掘进机的原因是，使用钻爆法方法至少需要12年才能完成项目。这是因为单头掘进不可能使用平洞进行多个作业，”罗宾斯尼泊尔总经理Prajwal Man Shrestha说。更一般地说，Shrestha先生认为该项目是一种证明掘进机确实可以承受复杂喜马拉雅岩石的方法。“由于喜马拉雅山脉的地质学还很年轻，而且还没有对其进行太多的调查，因此人们对新技术的使用略有担忧。只要有几个掘进机项目和更多的调查，将会表明掘进机技术将适用于喜马拉雅山脉。”
BBDMP是一个民族自豪感项目，它的成功对国家和掘进机行业都至关重要。预计将通过提高尼泊尔中西部地区的农业产量和促进该地区的社会经济发展，帮助缓解粮食危机。为这长12.2公里隧道作业的罗宾斯掘进机计划于2017年11月始发。
跨模式掘进在墨西哥城破纪录地贯通
2017年6月8日，包括墨西哥总统 Enrique Peña Nieto在内的一批项目官员庆祝了史诗隧道项目的最终突破。直径8.7米的罗宾斯跨模式掘进机是第一台在北美作业的跨模式掘进机，它完成了伊米苏泊尼特隧道二期 （Túnel Emisor Poniente II，简称TEP II）。这台掘进机兼并硬岩模式和土压平衡模式作业的跨模式掘进机XRE，可以在断层带、可变地面、浅埋深等地质掘进，以日掘进57米、周掘进231米和月掘进702米的速度刷新了的国家纪录。
“XRE具有很大的优势，因为它设计用于开放或封闭土压盾构模式下掘进；允许它在土壤或岩石中挖掘隧道。我们已经证实它的性能是非常有效的。” 业主Conagua，墨西哥国家水委员会TEP二期主管Ing. Juan Alberto Herrera Moro y Castillo说道。
这台独特的机器及其连续输送系统是采用现场首次安装调试的方案（OFTA）组装的，并且是为Aldesem、Provon和Recsa的承包商联合体设计的。罗宾斯跨模式掘进机的特点是，如配备可互换刀具的可转换刀盘，可互换的掘进机带式输送机和螺旋输送机，以及多速变速箱，以增加在困难地质下挖掘隧道时的扭矩。“这种设计的好处在于其卓越的推力和改变刀盘扭矩的便利性。如果机器卡在困难的地质下，这会使整个过程变得更容易，” RECSA隧道部门负责人Alberto Martinez说。
XRE机器于2015年8月启动，用于挖掘5.8公里长的废水隧道。这台机器安装在坚硬的岩石地质中，刀盘配备20英寸的滚刀。2016年初，掘进机撞击了几个接触带中的第一个，这是一条30米宽的断裂带，由破碎和块状岩石构成。虽然通过接触带的挖掘工作进展缓慢，但在更具挑战性的安山岩中，进度再次加快。在2016年3月中段贯通进入80 米深的竖井，随后进行检查和维护后，掘进机继续掘进。
2016年秋季在破碎安山岩中掘进时，隧道掘进机遇到了一个自然形成的洞穴，据信是过渡带中的岩石坠落或侵蚀岩石的古老地下湖体造成的。据估计，该洞穴的大小为90立方米，其中不稳定的地面面积约为57立方米。掘进机被停机，并立即采取措施使机器前的地面用聚氨酯泡沫稳定，然后用豌豆砾石和浆液的混合物填充洞室。
截至2016年10月底，掘进机已达到软土地面最后900米长的隧道段，并在那里转换为土压平衡模式。在最后一段浅埋深的隧道中，隧道顶部到住宅地基的距离低至4 米，地质具有再固结土壤的一致性。为了稳定软土，并将居住区以下的沉降风险降至最低，隧道施工人员从地表开始钻孔，每隔1.0米安装890根微型桩。他解释说：“我们能够做到这一点，而不会对TEP II路径沿途附近地区邻居的财产造成损害，也不会对该地区安装的道路或城市基础设施造成损害。” 承包商Aldesa的TEP II现场经理Francisco Miguel Lopez说。
现在隧道已经贯通，隧道将在投入使用前再灌注一个35厘米厚的二次混凝土衬砌。该污水隧道将对墨西哥城外西部地区的现有系统进行检修，以防止瓦尔多拉多的反复洪水。特别是，隧道将有益于Cuauttal Izcalli、Tlalnpantla和Atizapan de Zaragoza这些城市总共有210万居民。
美国第一台作业的跨模式掘进机“罗斯”
2017年5月30日，一辆直径为9.26米的罗宾斯跨模式掘进机在工厂验收。这台巨大的机器最初是在5月25日的新闻发布会上在俄亥俄州罗宾斯的索伦总部亮相的，之后被运往南部40公里的地方，用于在亚克朗建造俄亥俄运河拦截隧道项目（OCIT）。出席会议的有亚克朗市长Daniel Horrigan、罗宾斯首席工程师Dennis Ofiara和承包商肯尼·大林合资公司（Kenny-Obayashi JV）的项目工程师David Chastka。
掘进机具有土压平衡和硬岩单护盾两种作业模式的特点，是美国使用的第一台跨模式掘进机。它将从一个12米深的入口始发，并在软土地质下开挖长68米的第一段隧道区间，在转换为硬岩模式之前，过渡到183米长的部分面页岩区域，然后在全面页岩中继续驱动。超前钻探将使用两个探头钻头连续进行，以决定掘进机应处于哪种模式作业。”罗宾斯提供了一个强大的设计，我们相信将能够处理OCIT项目隧道驱动的所有挑战，”Chastka说。
机器的独特之处包括一个多功能刀盘，该刀盘的配置考虑了硬质岩石中的短软土段和硬岩长段（约占隧道的65%）。如果刀具堵塞，将使用滚刀和刮刀的组合。滚刀所需的滚动扭矩减少了25%，以支持在软土地下顺利旋转。XRE机器的电机已从原来的土压平衡模式配置中进行了调整，以允许驱动的打开模式段在降低扭矩的情况下提高电机转速。
通过一个耐用的螺旋输送机来清除渣滓，其第一段由耐磨板焊接而成。螺旋轴采用交叉舱口式硬面衬里，螺旋输送机外壳采用耐磨板和硬面衬里，整个传动装置都制定了磨损监测系统，以使设备在磨蚀硬岩地质下可以最大限度地提高开挖效率。罗宾斯项目经理Pablo Salazar对于在掘进机施工和设计过程中使用当地生产力感到自豪：“我们已经在俄亥俄州东北部地区制造了机器的大部分。许多部件都是在本地与次级供应商以及我们自己的车间制造的。”
这台机器被称为“罗斯”（“Rosie”），以纪念Rosie the Riveter，这是代表在第二次世界大战期间在工厂和造船厂工作的美国女性的标志。包括亚克朗居民Rose May Jacob在内的数百名在工厂工作的“Rosies”，为盟军的战争努力提供材料和军备。 掘进机将以卡车运输到工地，大型刀盘分为四件。 “整个装配过程允许承包商密切关注机器的测试，因此他们现在非常熟悉掘进机。在工地，我们还将为备件和人员提供即时支持，“Salazar说。 罗宾斯的工地主管将协助掘进机装配和至少前1000米的掘进。隧道掘进计划于今年8月开始。
亚克朗市的OCIT项目包括修建一个运输和储存隧道系统，以控制阿克伦市中心地区几个监管机构的综合下水道溢流（CSO）。环境保护局授权的项目包括1.89公里的运输和储存隧道，以及竖井、引水结构、加固下水道和相关结构。同意令规定，隧道必须在2018年12月31日前投入运营。
挖掘日本坚硬岩石的巨型泥水盾构机
罗宾斯公司最近被Obayashi-Taisei-Kosei合资公司选中，为广岛高速公路5号线建造一个硬岩泥水隧道掘进机。该机直径13.67米，将是日本第一台在硬岩中挖掘的大直径泥水盾构机。该隧道将长1.4公里，并将用钢筋混凝土段衬砌。
这台机器的生产是日本吉姆技术公司（Jim Technology Corporation）和罗宾斯的合资企业。这台机器是罗宾斯设计的，由 JIMT提供刀盘驱动和关节密封。据估计，地质条件包括最大强度190兆帕的花岗岩，高水压高达13巴。泥水盾构机设计配备专用的20英寸压力补偿滚刀挖掘高强度岩石，该滚刀采用专利设计，可在高压下有效工作。
这条新的高速公路5号线隧道将直接连接广岛市城区和一个主要的国家公路网，并有望改善通往广岛机场的通道。由于地面上有居民区，为了避免噪音限制，必须在有限的时间段内进行作业。为了满足城市内控制的运输限制，也有交付掘进机的限制，需要将设备分为小的可运输重量和尺寸，然后在现场组装。预计设备将于2018年投产，2020年建成隧道。
大型泥水盾构机的发展，从其耐磨特性和坚固的部件到高压刀具，说明了泥水盾构机的通用性。该掘进机有望扩大泥水盾构机在高压硬岩地质中的适用范围。
Robbins Celebrates Tough Tunnels for Clean Energy
In April 2017, a ceremony was held to celebrate the commissioning of the Dariali Hydropower Project in the Republic of Georgia. Many attended the ceremony marking the first carbon-neutral hydropower project in the world, including Georgian Prime Minister, Giorgi Kvirikashvili. The power station, an independent power project (IPP) developed through Dariali Energy Ltd, was a joint venture involving three other firms: Georgian private companies Peri Ltd and Energy LLC, and state-owned Georgian Energy Development Fund (GEDF). The Dariali HPP gathers water from the Tergi River and directs it through the headrace tunnel to the power house located near the Russian—Georgian border. Each year, the site will generate 500 GWhs of carbon-neutral energy, with 70 percent of power production occurring during the country’s summer months.
Robbins also invested in the project by gaining equity through supplying tunneling equipment and services in consortium with contractor Peri. “Robbins understood the risk in the tunneling portion of the project and we were compensated for taking on part of the risk. Peri is a long-time customer, as we supplied a TBM to them 15 years ago for a small project in Georgia. It was great to be invited to invest and risk share on this project, and to work together again,” said Robbins President Lok Home. The 5 km (3 mi) long headrace tunnel for the power station was bored with the use of a 5.5 m (18 ft) diameter Robbins Main Beam TBM starting in February 2012.
Due to the remote and mountainous location of the jobsite 160 km (100 mi) from the capital Tbilisi, the machine was shipped in pieces to contractor Peri’s workshop, where they were refurbished under Robbins supervision and then delivered to the site to be assembled. Each piece was transported by truck down narrow, winding roads that eventually gave way to dirt paths. Assembly at the jobsite was difficult, as the project site at a 1,700 m (1.0 mi) altitude was blanketed in snow and components arrived in December. Bone-chilling temperatures often reached negative 15 degrees Celsius (5ºF), and 40 below with the wind chill factor. Once the machine had launched, it encountered difficult ground including slate, sandstone, limestone and malms with fault zones.
“The main challenges we faced were boring the tunnel at a 6 percent incline and having restricted access to service the machine. There were also two major landslides that delayed the project for over a year,” said Home. After the first landslide, the access tunnel, which had allowed mud and water to enter the power station, had to be relocated at a higher elevation and facing away from the river valley. When the machine was nearing the end of its bore, a second landslide blocked the exit portal for the machine as well as access to the main highway. Despite these challenges, tunneling crews persevered and the machine successfully holed through in October 2014.
Throughout the construction process, careful steps were taken to minimize the carbon footprint. Although the plant’s energy production is carbon emission free, construction of the plant was not. To offset these emissions, 7,000 seedlings are being planted all around the area in a reforestation effort. In years to come, the trees will absorb enough carbon dioxide to compensate for the emissions produced during the construction of the hydropower plant.
Overall, said Home, there is much to celebrate as the project has immense benefits: “Not only does it provide affordable electrical power for the country with essentially no pollution effects, but it also provided jobs during construction and will continue providing jobs during its operation and maintenance.”
Robbins TBM Takes on Eighth Bore for Galerie des Janots Project
A Robbins TBM, recently christened “Augustine”, is being commissioned to undertake its eighth bore after being launched by contractor Eiffage Civil Engineering on March 3. The TBM, which was extensively modernized and upgraded during the rebuild for the Galerie des Janots project in La Ciotat, France, has previously completed seven other successful projects across Europe and Hong Kong. This time, it will bore the Janots gallery to improve access to water in the communities east of the Aix-Marseille-Provence metropolis (Cassis, Roquefort-la-Bédoule, La Ciotat and Ceyreste). “It’s a single machine 3.5 meters (11.5 ft) in diameter, 250 metric tons (275 US tons), and 135 meters (443 ft) long, that will work 24 hours a day for almost 10 months during this operation,” says Marc Dhiersat, Project Director of Galerie des Janots for Eiffage.
Currently, the machine is ramping up as back-up decks are being installed. As of April 2017, the machine has bored more than 51 m (167 ft), mainly encountering limestone. “Limestone is a rock easy to dig, but one can be confronted with the phenomenon of karst,” explains Loïc Thévenot, Director of Underground Works for Eiffage. “For this purpose, the tunnel boring machine is equipped with a probe drill. If the karst is small, we will fill it with concrete. If it is large, we will erect a small parallel gallery.”
Galerie des Janots is one of the fourteen operations designed to save water and protect resources, which are being carried out by the Aix-Marseille-Provence metropolis, water agency Rhône Mediterranean Corsica, and the State Government. The future Janots gallery will replace existing pipelines currently located in the railway tunnel that have significant safety and vulnerability deficiencies with estimated water losses of 500,000 cubic meters (132 million gallons) per year. According to Danielle Milon, Mayor of Cassis, “This is an investment of 55 million euros (USD $59 million) with 11 million in aid from the water agency. This project required 10 years of reflection and work to improve water supply. And water is essential for the development of each municipality, and for citizens’ well-being.”
Augustine is boring a tunnel 2,750 m (1.7 mi) long, and will pass under Le Parc National des Calanques, with cover between 15 and 180 meters (50 to 600 ft), in order to replace the pipes that are currently being utilized for the water supply networks. “[The current pipes] have a capacity of transit limited to 330 liters (87 gallons) per second, which is largely insufficient in the summer period. The objective of the operation is to increase to 440 liters (116 gallons) per second,” says Dhiersat. Once the project is complete, networks can easily be maintained in comparison to the old pipes currently running beneath the railway.
罗宾斯单护盾参与修复世界最长隧道
罗宾斯已经完成了一台独特的隧道掘进机机的制造和测试，该设备将用于修复世界上最长的连续隧道。掘进机将用于翻修纽约市特拉华渡槽的一段，这是一条长137公里的隧道，每天提供约50%的城市饮用水。在2月份的两天时间里，来自业主纽约环境保护部（NYDEP）、咨询公司麦克米伦·雅各布斯（McMillen Jacobs，简称MJ）和合资公司承包商基威特·谢赫（Kiewit-Shea Constructors，简称KSC）的代表前往俄亥俄州索隆的罗宾斯工厂，见证这台定制掘进机的工厂验收测试。
罗宾斯单护盾隧道掘进机将开挖一条隧道，以取代3.8公里长的特拉华渡槽。特拉华渡槽目前每天向哈德逊河泄漏约7500万升的水。对特拉华渡槽的调查可以追溯到十多年前，发现隧道衬砌出现裂缝。虽然使用自动水下运载工具进行的几次检查表明这些裂缝是稳定的，但确定它们不能从现有隧道内修复。纽约市随后决定在河下修建一条新的隧道以绕过渗漏。
径为6.8 米的单护盾硬岩掘进机，以安全密封压力高达30巴，并在各种坚硬岩石条件下运行。特拉华渡槽于1944年完工。在最初的施工过程中，工作人员记录了每天75至1500万升的地下水流入量。由于这段隧道位于哈德逊河（Hudson River）下方183 米处，因此，流入的水受到巨大的水头压力，因此需要独特的隧道技术。
由于渡槽修复所带来的挑战，例如地质困难和大量的水涌入，因此必须相应地设计掘进机。困难的地质解决方案（DGS）功能，包括强大的钻机、注浆和涌水控制系统已纳入机器的设计中，以克服预期的挑战。“这种隧道掘进机的一个独特特点是可关闭的铲斗，这使得铲斗仓可以被封闭，” KSC隧道经理Niels Kofoed说。“我们预计，如果隧道开挖部分的地下水流量（分流）导致环空注浆冲刷，这将是一个关键特征。一旦隔离墙关闭，地下水流停止，可对预制衬砌进行二次注浆，有效切断分流水流的流动路径。”
罗宾斯项目经理Martino Scialpi进一步指出，“掘进机的设计排水能力为9500升/分钟。机器在盾体中配备两个钻机，用于在16个不同位置钻探，在管片安装器上配备第三个钻机，用于在盾体另外14个位置钻探。钻探和开挖前灌浆将是控制和减少水流入的常规工作。“此外，水力驱动的高压下孔锤将允许，在需要的时候，可以在机器前方60至100 米、高达20巴压力下钻探。
为了提供始发和回收隧道设备的通道，在纽约纽堡和瓦平格镇建造了两个深井，两个深井将是旁通隧道的入口和出口。由于可用空间有限，项目现场本身对设备的组装和始发也构成了挑战。
罗宾斯与KSC密切合作，确保设备部件的设计和尺寸，以便所有部件都能用承包商的起重机可以承受，并安放在270米深的窄窄的洞室里。机器组装完成后，预计将于2017年秋季开始掘进。
罗宾斯双护盾在安第斯山脉下掘进
智利的秃鹰水电站（Los Condores）是一个高深埋、坚硬岩石的挑战，隧道上方有500米的岩石，海拔2,500米的高空作业现场。截至2017年1月，直径4.56 米双护盾隧道掘进机已完成900米长的进水口隧道的开挖，并正在顺利进行引水隧道第一段的开挖工作。该机器于2016年5月27日开始其旅程，自那时起，已总共挖掘1,300米以上的隧道。
机器启动的过程非常艰难，需要在未铺路面的山区道路上运输掘进机部件和车辆。承包商Ferrovial Agroman负责秃鹰水电站项目的进水口隧道，并充分意识到与机器始发相关的挑战：“工作地点是由于其崎岖的地形和安第斯山脉的地理位置，这是一个很大的限制。由于这些挑战，我们迫切希望以高效的方式开展工作，”Ferrovial Agroman的隧道生产经理Pello Idigoras说。
该工地位于智利圣地亚哥以南360公里，是一个新的150兆瓦发电厂和进水口隧道的一部分。罗宾斯双护盾掘进机正在对两段进水口隧道进行开挖，第一段长度为6公里，第二段长度为4.4公里）。两条隧道之间的一段将通过机械掘进和爆破进行开挖，以连接两条隧道，使进水口隧道的长度约为12公里。该项目增加了该国的能源生产，从而有助于全面改善该国公民的福利，” Idigoras说，已完成的水电项目将对周边地区产生影响。
该隧道位于智利莫勒山区，目前正在两种岩石中掘进：沉积岩和火山岩。岩石在强度高达100兆帕的下进行了测试，其中至少有两个断层带，第一个断层带已经在流纹岩、安山岩、凝灰岩和角砾岩中穿过。对于Idigoras，条件非常适合双护盾隧道掘进机：“我们有质量良好的中硬岩石，适合采用双护盾开挖。”他说。尽管如此，一些具有挑战性的领域仍然存在。为了应对这些条件，包括稳步增加水流入率高达3500 升/分钟，承包商正在使用水泥灌浆和化学灌浆聚氨酯和泡沫。预计会采用此类地质处理技术，罗宾斯双护盾旨在有效应用这些技术。
随着隧道掘进机的开挖，隧道采用250 毫米厚、1.2 米长的混凝土管片，采用4+1布置。这台机器目前正在以每20小时掘进25个环的速度进行。工作人员分两个10小时轮班，一个4小时轮班专门负责维护。Idigoras 认为隧道掘进机的性能和入口隧道的完工视为巨大的项目里程碑，尽管还有很多工作要做。”经过数月的工程、制造、安装和调试，我们很高兴看到这个结果。到目前为止，不可能说出所有参与该项目的人的名字，但作为一个整体，他们已经设法使掘进机开始挖掘和钻井。”
Robbins TBM dubbed "Driller Mike" digs Atlanta
After an Onsite First Time Assembly (OFTA) lasting just 2.5 months, Atlanta Georgia, USA’s newest TBM, dubbed “Driller Mike”, made its initial startup on October 13, 2016 and ramped up to full production two weeks later. Atlanta’s Mayor Kasim Reed and city officials gathered with local and national media to celebrate the occasion. The 3.8 m (12.5 ft) diameter Robbins Main Beam TBM is now boring the 8.0 km (5.0 mi) Bellwood Tunnel after being walked forward 100 ft into a starter tunnel. The Bellwood Tunnel path will travel from an inactive quarry and run below a water treatment plant and reservoir before ending next to the Chattahoochee River.
The project was green-lighted by the City of Atlanta’s Department of Watershed Management due to the city’s current emergency water supply shortage. The PC/Russell JV, the project’s construction manager at risk, sub-contracted with the Atkinson/Technique JV to operate the TBM and will oversee construction of various intake and pumping shafts as well as final lining operations. The project is of utmost importance for the City of Atlanta, explained Bob Huie, Sr. Project Manager for the PC/Russell JV. “Right now, the downtown area’s emergency water supply is approximately three days. With the tunnel the supply will increase to between 30 and 90 days. To be a part of the city’s emergency water supply solution is huge. This tunnel will protect the city for a very long time.”
With the tunnel on the fast track, swift TBM assembly was key. The OFTA process involved coordination by multiple crews at the large quarry site. “The OFTA went very well. The overall assembly process was well organized and supervised by the Atkinson/Technique JV and Robbins. We had a good team of folks to put it all together,” said Huie. He continued: “This is a unique job where there’s a lot of people with a variety of backgrounds, but everyone came together to make the OFTA happen.”
The Robbins TBM is now excavating in granite, with at least 300 m (1,000 ft) of zones in three separate areas that will require continuous probing. In a section directly below an existing reservoir, monitoring will be particularly crucial to ensure no water inflows occur. The Robbins machine will also be required to negotiate several curves: “We have one curve in the first 300 m (1,000 ft) and the main 370 m (1,200 ft) radius curve is 1,800 m (6,000 ft) in. We plan to do short TBM strokes in this section™bout 20 cm (8 inches) to 30 cm (1 ft) shorter than normal to get through the curves,” said Larry Weslowski, Tunneling Superintendent for the PC/Russell JV.
Excavation is scheduled to be completed in the first quarter of 2018. After final lining, the tunnel will be filled with water and the quarry site will become Atlanta’s largest reservoir and park, totaling hundreds of acres. While the park site is a bonus for residents, the water storage capacity it will provide is critical. Nearly 1.2 million customers, including 200,000 passengers who pass through the world’s busiest airport every day, count on the water supply each time they turn on the tap. “If the city were to lose water supply for a day, the estimated economic impact would be at least USD $100 million per day. If you consider that this is a USD $300 million project, that seems a pretty good investment in comparison to what could happen,” said Huie.
Bangalore Fanfare Marks Final Breakthrough for Robbins EPB
On September 23, 2016, Bangalore’s last TBM for the city’s metro rail project broke through, marking the end of TBM tunneling on the Namma Metro phase 1. The Robbins-operated machine, known as “Krishna”, bored a 750 m (2,460 ft) drive through challenging conditions between Chickpet and Majestic stations. Cleanup and final commissioning of the tunnel will be completed in 2017, and is the last obstacle before owner Bangalore Metro Rail Corporation Ltd. (BMRCL) can open the Malleswaram-Majestic link. The TBM’s sister machine, “Kaveri”, completed a parallel tunnel in June 2016.
The success follows a gauntlet of challenges on the two tunnel sites. Due to severe delays on the original tunnel drives, Robbins was approached and asked to take over the operations of the remaining two competitor-manufactured TBMs in February 2015. After obtaining agreement from the project owner and the contractor, Robbins took over the responsibility for all aspects of the underground operations. “We provided a team of over 60 staff including TBM operators, TBM technicians, ring builders, a grouting team, and more. We were also responsible for running surface installations and equipment such as the grout batching plant, gantry cranes and power supply. Contractor Coastal Projects Ltd. (CPL) provided a team of people including surveyors, QC engineers, and loco operators who reported directly to our site management team,” explained Jim Clark, Projects Manager for Robbins India.
The Robbins crew carried out tunneling operations while the Chickpet station was being constructed around them to mitigate delays incurred before they took over project operations. The project’s most difficult challenges included a low overburden and unconsolidated ground along the alignment, and the discovery of several uncharted wells directly on the alignment. Difficult ground frequently prevented proper pressurization during cutting tool replacement, requiring a grout solution to be pumped in to fill voids and left to cure. Initially the curing process took up to 36 hours, but with improved application methods this was reduced to a 12-hour curing time.
Another challenge involved the sensitive building structures along the tunnel path. Issues with surface vibration, explained Clark, required that cutterhead speed be limited to 1.8 RPM during the day shift and 1.2 RPM during the night shift. Despite the obstacles, the TBMs advanced at rates of up to 50mm (2 in)/min in highly weathered rock.
“This is an industry first, wherein a TBM manufacturer has utilized their in-house expertise and knowledge to take on this level of responsibility for a project,” said Clark, addressing the magnitude of the successful breakthroughs. “The fact that it was “˜a first’ and we were successful in bringing this high-profile project back on track is a great achievement for The Robbins Company.”
Now that tunneling is complete, the North and South runs of the Namma metro will be connected–a line that, once in service, will carry an estimated 40,000 passengers daily. It is anticipated that Phase One of the metro will be opened in its entirety in 2017.