2383

Indication 4 – by the tunnel depth.

4.1.The shallow tunnels (up to 10 m deep).

4.2.The deep tunnels (over 10 m deep).

Indication 5 – by the shape of the tunnel cross section.

5.1.Tunnels of a rectangular cross section.

5.2.Tunnels of a circular cross section.

5.3.Tunnels of a horseshoe shape cross section.

III. Match the English and the Russian equivalents.

IV. Use the words in the list to write the opposite of the phrases below. plain, rock, shallow, above-ground, pedestrian, circular

What indication do the tunnels from 1 – 5 refer to?

V. Complete the following sentences. Choose your answers from the box. There are more words than you will need.

1.A tunnel is an underground … for a road or railway through a hill or under a river or the sea.

2.Any soil driven for a tunnel is called …

3.A lining is the … tunnel element.

4.Submarine tunnels can be … through the rock.

5.A portal connects the tunnel with the …

6.Tunnels can be classified according to the shape of the tunnel...

cross-section, rock, basic, ground surface, bored, passage

VI. Look at the following diagram. What is the base of this classification? Can you complete it? Draw a similar diagram in your notebook and let your partner complete it.

IX. Look at the pictures below (fig. 12, 13). Try to describe tunnel shapes.

Horseshoe (flat bottom provides roadway)

Fig. 12

Circular (strongest shape)

Fig. 13

X. Work in pairs. Speak about the longest railway and highway tunnels of the world using the table below. You may use the following phrases for help:

As far as I know…; do you know what…; what is the longest…; what about…; as far as I remember…; what is its length…; somewhat about…; let me see…

Text 33 

Find the words you have read in the text below and translate the word combinations having these words. Use the words in the sentences of your own.

II. Work in pairs. Think of 2 or 3 questions using the words from Ex. I. Answer the questions of your partner.

III. Read the following text and say what influences the choice of tunneling technique.

ROCK TUNNELING

A tunnel is an underground way, which passes into a daylight at both ends. To cope with different geological conditions the miners adopt various driving techniques. Cutting is the most ancient technique of tunneling.

The three principal features determine the cutting tunneling technique:

1.The tunnel cross section is divided into several areas which are developed in turns.

2.The lining may be built in the developed sections while the ground may be excavated from the rest of the tunnel face.

3.The temporary tunnel support of timber is used during the tunneling.

The process of the cross section development for hard rock tunneling is as follows. Initially the bottom adit is worked and the temporary tunnel support is built there. Then the vertical and inclined shoeflies are made from the bottom adit. They prepare the top adit or the top drift development.

The next operation to perform is to open the calotte i.e. the development of the top tunnel section. This tunneling stage requires, lining in the tunnel vault. Then the miners excavate the ground from the middle section (central block) and at last in the side sections of the tunnel (side blocks). The ground having been developed, the builders finish the lining erection.

Almost every tunnel job will involve short stretches of bad ground requiring a special technique of driving. The most important problem to solve is to choose the proper method for the ground development depending upon the changeable geological conditions. Rock tunneling involves various techniques of rock development for different ground types.

Hard-rock tunneling needs explosives, i.e. the rock must be broken by blasting. It requires blasting, loading the broken rock transporting it from the face, drilling and supporting the rock and ventilation after blasting. Safety is always the first consideration in tunneling and ventilation takes away the blasting fumes.

Hard-rock tunneling requires «drill-and-blast» technology. It represents the following stages: 1) to drill a blast-hole in rock with the aid of miner’s picks or blast-hole drills; 2) to place a charge in blast holes; 3) to set off a charge in blast holes; 4) to remove the toxic blast fumes from the face by ventilation; 5) to provide the face inspection for revealing the charges that possibly did not blast.

Soft rock tunneling needs miner’s picks, blast-hole drills and loading machines which are most efficient for sand, sandy loam and other types of incoherent ground. The broken rock is loaded into skips driven by electric locomotives, which run along the narrow-gauge track. The gauge in tunnels ranges from 6000 mm to 750 mm or 900 mm. Sometimes the broken rock is moved away by a conveyer belt.

IV. Find 8 pairs of antonyms:

ancient; permanent; fill; modern; vertical; bottom; previous; horizontal; temporary; begin; top; steady; excavate; following; finish; changeable

V. Read about cutting technique once again and label fig. 14.

4

7

3

8

1

2

Fig. 14

VI. Work in pairs. Answer the question of your partner. Use the phrases below to make up questions.

Model: - Are they revising the project?

- No, they aren’t. They have already approved it.

To choose the proper method; to excavate the ground; finish the lining erection; to discuss geological conditions; to blast the rock; to examine the ventilation; to transport the broken rock.

VII. Complete the sentences.

1.Cutting technique of tunneling is the most … one.

2.During the tunneling according to cutting technique the … is used.

3.First the bottom … is worked.

4.The next stage is opening the …

5.The final stage is erecting the …

6.Hard-rock requires needs …

7.… is always the first consideration in tunneling.

VIII. Complete the table without looking back at the text.

Home Exercises

I.Memorize the words from Ex. I page 127.

II. Give a short summary of the text. Express your attitude to the problem of rock tunneling.

Text 34 

II. Scan the text for about 10 minutes. For questions 1 – 4, choose the answer (A, B, C, D) you think fits best according to the text.

1. The tunnel boring machines are used to...

A riddle the ground with pockets of methane gas. B increase water pressure.

C minimize the risk of the rock inrush. D understand engineering.

2.A shield is a steel… A circle.

B box. C oval.

D cylinder.

3.Usually the shield length is … A about 30 m

B above 50 m. C under 30 m. D about 50 m.

4.Most shields must be assembled… A in the shop.

B on the job. C in the tunnel. D in the rock.

III. Read the text and check your answers.

SHIELD-DRIVEN TUNNELS

Cutting as well as fire-setting techniques have been replaced by a higher level of technological and engineering understanding because the ground can be riddled with pockets of methane gas and stretches of high pressure water. All this poses great risk to the works. The tunnel boring machines (TBMs) are used to minimize or even to escape the risk of the rock inrush, great labor requirements for the temporary support construction and ground excavation by separate sections. Technological advances resulted in shield driving. Mark Brunnel, a celebrated engineer created the idea of employing a shield to lead the

tunnel excavation.

A shield is a steel cylinder equipped with rotating cutter blades that supports a tunnel as it excavates. Its creation has made possible underwater tunneling through soft ground, sand, sand loam, silt, etc. Shield tunneling allows to develop the full cross section of the tunnel without dividing it into separate areas. In this case the driving speed may be 15 – 30 m per day.

The modern TBMs may be described as high-tech cylindrical factories, complete with laser-directed guidance and the now obligatory canteen and sleeping quarters. The machine diameter ranges from one to ten meters and depends on the tunnel purpose. The shield length reaches 30 or even 50 m.

The basic problems of shield tunneling are to overcome the ground frontal resistance and ground friction on the cylinder skin when shields advance. The so-called shoving jacks are mounted along the shield perimeter to solve these problems. The shoving jacks are rested by their ends against the tunnel lining and shield ring girders.

Rotating cutter blades or roller bits are called cutting edge. It cuts through the rock. The cutting edge may have a forward extension of its top section. This extension is called a hood.

Under its protection the miners can set the breast board far enough ahead the shield face to permit a full length shove.

Working pockets and bulkheads are also essential shield parts. Horizontal and vertical frames divide the front part of the large shield into pockets. These frames stiffen the shield structure against distortion from the loads on the cutting edge and provide platforms for the workmen to stand on when attacking the face and making the primary lining.

The bulkhead type of shield is used for certain kinds of ground. A port is built into the bulkhead of each working pocket to admit silt or soft clay to the tunnel through the shield.

Proper operation of the shield requires great skill and experience. Shield tunneling represents the advantageous excavation of underground space from many points of view. But it has some disadvantages as well.

First, there are non-mechanical shields and the miners have to use hand tools for the ground excavation, loading the muck and the lining erection.

Second, each type of the ground requires different shields and different technique in handling the shield. The ground may vary from section to section so the system of driving must be flexible enough to meet all the anticipated ground conditions.

Thirdly, shields can be assembled in the shop and shipped to the job site in one piece in case they are small. However, most shields must be assembled on the job, at the portal or at the bottom of the shaft because of their size. These operations are very expensive and call for considerable labor input. Besides, shield start up and dismounting involves heavy outlays. That is why it is not

expedient to employ TBMs in all sorts of tunneling.

IV. Match the English and the Russian equivalents.

V. What notion is described?

-to make a hole or a channel by digging the ground;

-the flat cutting part of a knife;

-the part of a tool that cuts or grips when twisted;

-pulling or twisting something out of its usual shape;

-a dividing wall or barrier

VI. Work in pairs. Put 5 special questions to the text and answer the questions of your partner.

VII. Copy and fill in the table using the information above and your own knowledge.

Shield-Driving Tunneling

Home Exercises

I.Memorize the words from Ex. I page 130.

II. Compare cutting technique and shield-driven tunneling.

Text 35 