New concept of tunnel boring machine: high performance using water jet and diamond wire as rock cutting technology

Abstract Tunnel boring machines are important tools in underground infrastructure projects. Although being well established equipment, these machinesare based on designsof more than 60 years ago and are characterized by big dimensions, enormous weight and high power consumption. Commercial aspects should be noted too. The model adopted by the TBM industry requires constant replacement of cutter discs and specific labor skills, usually offered by the same manufacturingcompany. In some cases the cost of replacement parts and technical assistance can be higher than the acquisition cost of an entire machine. These aspects are no longer compatible with the concept of sustainability that is an important aspect of currentsociety. While the technical characteristics require a large quantity of steel and several inputs, the adoptedmodel is not competitive. One alternative is looking for new technologies that break the old paradigms and allow the development of high performance concepts with lower social and environmental impact. This studydealswith this opportunity by proposing a high performance tunnel boring machine that makes use of high power water jet and diamond wire to compose a double shield cutter head. It works in two stages. In the fristone, an annular cut is executed by hydrodemolition,and in the second one, the diamond wire station slices the rock core. Only with the action of diamond wire is the rock core separated from the rock mass and the removal process is finished. A smart water jet nozzle movement system is described and non circular tunnels can be executed. The new technologies involved requirea different type of backup system, lighter and smaller. The non-existence of mechanical contact between the equipment and the rock mass at theexcavation front allows low power consumption. The advanced rate and primary excavation cost analyses can also be encountered herein. It shows that it is possible to reach an advanced rate of 174 m/day in soft and porous rock and 0.64 m/day in hard and non porousrock, whereas the NTNU method indicates only 55m/day and 13m/day underrespective conditions. On the other hand, the excavation cost is high for both conditions. One option is to use sand as an abrasive in the water jet process, reducing by half the primary excavation cost. It is reasonable to say that the proposed concept can be considered as an alternative for tunnels in soft rock and high porosity, and needs better performance of the water jet system to become an alternative for hard rock.摘要 隧道掘进机（Tunnel Boring Machine, TBM）是地下基础设施工程中的关键装备。尽管该类设备已得到广泛应用，但其设计理念仍基于60余年以前的方案，普遍存在尺寸庞大、自重巨大、能耗高昂等特征。此外，其商业运维模式同样存在不容忽视的问题：TBM行业通用的运维方案要求频繁更换盘形滚刀（cutter disc），且所需的专业操作技能通常仅由原制造厂商提供。在部分场景中，备件更换与技术支持的成本甚至高于整机采购成本。此类特性已与当前社会倡导的可持续发展理念愈发相悖。该传统机型不仅需要消耗大量钢材与各类原材料，市场竞争力也愈发不足。对此，可行的解决方案是探索打破旧有技术范式的新技术，开发兼具高性能与更低社会环境影响的新型掘进理念。本研究针对该需求，提出一款搭载高功率水射流与金刚石绳锯的高性能隧道掘进机，其核心为双护盾刀盘（double shield cutter head）。该机型采用两步掘进工艺：第一步通过水力破碎（hydrodemolition）完成环形切口作业，第二步由金刚石绳锯工作站切割岩芯；仅依靠金刚石绳锯的作用即可将岩芯与岩体分离，完成掘进出渣流程。本研究还阐述了一套智能化水射流喷头移动系统，可实现非圆形隧道的掘进作业。该新型技术体系需要配套轻量化、小型化的后方支撑系统。由于掘进工作面的设备与岩体之间不存在机械接触，整机能耗得以大幅降低。本文同时涵盖了掘进效率与初始开挖成本的分析结果：在松软多孔岩体中，该机型可实现174米/天的掘进效率，在坚硬非多孔岩体中则可达0.64米/天；而根据NTNU法，对应工况下的掘进效率仅分别为55米/天与13米/天。但另一方面，两种工况下的开挖成本均偏高，可通过在水射流工序中使用砂石作为磨料，将初始开挖成本降低50%。综上，所提出的掘进概念可作为松软多孔岩体隧道工程的备选方案；若要将其应用于硬岩隧道，则需进一步优化水射流系统的性能表现。