Figure 19. 7 Technological Process by the Slurry Shield Complex

Though shields require considerable time for setting-up, they are easily operated and ensure an accurate breakthrough when they dig toward each other from opposite tunnel ends in hostile ground environment. The TBM operator uses control systems to avoid any wobble and eccentric rotation of the cutter head because the diameters of the tunnel and the cutting head must be equal in sizes. Driving a smooth curve with a shield requires great skill and experience. It is costly or even impossible to withdraw shields from the heading. Each of the two opposite shields may dig a short spur to steer them away from the path of the tunnel for permanent sealing.

Shield tunneling has many advantages; however, it has some disadvantages as well. First, there are non-mechanical shields and the workers have to use hand tools for loading the muck or placing the lining segments. Second, only small shields are assembled in the shop and. They are shipped to the job site in one piece. Most shields are assembled in situ, at the tunnel portal or at the bottom of the launching shaft. Assembling, starting and dismounting the shield in situ require a special mounting platform, and are very expensive and labour consuming operations.

Civil engineers consider shields to be a promising area of improvement. They have devised multiple-headed TBMs for simultaneous boring of two or three parallel tunnels (fig.19.1b). Recently built shields are able to turn a corner up to 90° during a tunnel boring operation. The necessity for drilling core samples and boring probe headings ahead of tunnel face has been also reduced due to a virtual CAT scanning that is generated by sound waves which are transmitted through the earth. The trend in TBM design is towards remote control systems. It will improve workers’ safety and reduce the working time in the underground space.

Exercises

19.2 Find the Russian equivalents for the following English terms

Core sample, discharge equipment, excavation, fluid conveyance, fractured rock, launching shaft, obstructive inclusions, permanent sealing, rotating head, screw conveyor, shale, shielded TBM, slurry feed equipment, slurry shield, stand-up time, steel strap, swelling clay, tungsten, wobble

19.3 Find the English equivalents for each of the Russian terms

Вынутый грунт, герметичная камера грунтопригруза, ответвление от трассы тоннеля, остроконечные режущие зубцы, пульт управления, рабочая ячейка щита, сбойка, скорость проходки, сыпучий грунт, тоннель со встречным движением, трасса тоннеля, трубопровод для глинистой суспензии, управление щитом, хвостовая часть щита, щитовой способ проходки тоннелей

19.4 Complete and translate the following sentences using the list of word combinations below

1. The term (“слабый грунт”) means soil that requires immediate support upon excavation.

2. The term (буровой метод сооружения тоннелей) comprises such excavation methods as (механизированная проходка).

3. Tunnelling is a process, always carried out in an (неопределённые геологические условия) and requires special knowledge and technological resources.

4. TBMs are able to construct long tunnels in less (прочный грунт) with high water pressure or even in sub-aqueous environment.

5.  The TBM consists of an extending frame, (роторный рабочий орган), a non-rotating stabilizing device, a (система продвижения щита) and a conveyor that extends along the length of the TBM.

6. Mounted at the very front of the TBM a rotating head (вращающаяся головная часть щита) carries a series of (дисковые шарошки) to spall the surface of the tunnel face during a tunnel boring operation.

7. Concrete segments are secured in place behind the TBM as soon as possible to assure that any (обломки горных пород) from the instable tunnel roof is prevented from (обвал горной породы) and falling into the tunnel.

8. Herrenknecht mixshield can be considered a slurry machine or (щит с компенсацией давления горных пород) to cope with all ground conditions.

9. The (известковый грунт) under the English Channel was bored by the TBMs produced by Japanese companies Kawasaki Heavy Industries, Mitsubishi Heavy Industries, by the US engineering company Robbins, and by British-built machines.

10. Bored tunnelling techniques include tunnels constructed by TBM and tunnels constructed by hand tools and machines, that use an observational approach with temporary support of the (выработка) called NATM tunnels.

Word combinations: “Bored tunnel construction methods”, bored tunnelling techniques, chalky earth, competent ground, debris, disk cutters, EPB machine, excavation, mechanized driving, propulsion means, rotating head, “soft ground”, toppling, uncertain ground conditions.

The Word List

1. Back-up system	консольная часть щита
2. Bentonite slurry	бентонитовый раствор
3. Cave-in	обрушение свода или стен тоннеля
4. CAT scanning	компьютерное сканирование
5. Cutting head	передняя ножевая часть щита
6. Cutting face, cutting edge	ножевое кольцо проходческого щита
7. Cutting disk	резец, дисковая шарошка
8. Milling cutter	бурильная головка, шарошка
9. Mud pressure	давление бурового раствора
10. Gripper arm	башмак гриппера
11. Open-face type TBM	щит с открытой головной частью
12. Pressurized slurry	находящаяся под давлением глинистая суспензия
13. Thrust cylinder	толкающий цилиндр (домкрат)