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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.

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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.

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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.

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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

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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.

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Leading up to it on both sides are several miles of approaches built on concrete stilts and roofed with concrete to protect the roads from snoe and avalanches and make them useable throughout the year. Up to now the Great St. Bernard Pass has been closed much of the year by snow.

More than 30.000 cars a year are expected to use the tunnel. Tolls range from 2.10 dollars to 4.65 depending on the engine, size of the car and the number of passengers. There are 12 other important tunnels under the Alps in central Europe all for rail traffic. Soon the second Alpine motor tunnel will be ready. It will connect Italy and France under Mont Blanc.

II. Read the text word by word and complete the following words.

Tr · · · ic ; ro · ·; · in · · ·; r · · d · e ·; con · · · · e; · · ll; · · nn· · ·; p· o· e· t; t· · · · l.

III. Give Russian equivalents to the following word combinations:

to be under construction; to be under way; to be used to excavate; to make something useable; throughout a year.

IV. Give one word instead of the underlined word combinations.

gradeate, extend, mechanize, accumulate, evacuate, contract, weaken, prolong, anchor

1. Regular maintenance will give the tunnel a longer life. 2. The ends of the cables are fixed firmly and safely in foundations. 3. The bar of metal will get shorter while cooling. 4. It is first necessary to take the air out of the tube by means of an air-pump. 5. The motorway will gradually be made longer. 6. This work was formely done manually, but now it is carried out by machines. 7. More and more carbon collects in the tunnel. 8. The tube is marked off at intervals as the distance from the transmitter increases.

V. Read the text and say if these statements are true, false or not given.

1.The first automobile tunnel under the Alps in Europe connect Italy and France.

2.The Great St. Bernard Tunnel is 3.8 miles long.

3.Digging between Italy and Switzerland was made manually.

4.Lining of the tunnel under Alps is made of reinforced concrete.

5.Tolls are constantly rising.

6.The second Alpine motor tunnel is built under Mont Blanc.

VI. Answer the questions to the text.

1.When was Europe’s first automobile tunnel under the Alps opened?

2.What was the inside of the tunnel lined with?

3.How many cars a year are expected to use this tunnel?

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4. What will protect the roads from snow and avalanches?

VII. Make up a circle. Try to tell a collective story about the first automobile tunnel under the Alps (every student must say a sentence).

Text 36 

II. What do you know about the Mursey Tunnel? Where is it situated? When was it built? What is its length?

III. Read the text and check your answers.

THE MERSEY TUNNEL

The cities of Liverpool and Birkenhead are joined by a tunnel which goes under the river Mersey. It is the famous Mersey Tunnel, one of the biggest underwater tunnels in the world. Its total length is over two and a half miles. During the year 1956 more than 10 million vehicles used the tunnel.

Its construction has been a great engineering achievement. The work started in December 1925 on the Liverpool side and a few months later on the Birkenhead side. It had been decided to approach the work by driving from each bank of the river two pilot headings, an upper and a lower one, which would meet under the middle part of the river.

Vertical shafts were sunk on both sides of the river and the excavation work began. At first the working face on the heading was broken up by compressed air drills, later explosives were used. The headings met on the 3rd of April, 1928, twenty-seven months after the work had began. The divergences in line and level were found to be about an inch, showing how accuratly and correctly the survey work and the determination of working levels had been done.

The next stage of the work was the enlarging of the pilot headings into the full-sized tunnel. Steel, cast iron and concrete were used in lining the tunnel.

From the very start it was realized that the ventilation of a tunnel of such a length, which was to be used by vehicles propelled by internal combustion, would be a very difficult problem. Finally, a system of ventilation was adopted

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in which air is blown into the tunnel through ducts at roadway level and drawn off along the roof through exhausts.

The Mersey Tunnel was completed in 1934. It was opened on the 18th of July 1934. At the time it seemed a complete solution of the communication difficulties that had existed between Liverpool and Birkenhead. Today it is obvious that the solution has been only temporary. The ever-increasing exports from the part of Liverpool and the rapid development of Merseyside as an industrial centre have resulted in a great increase in motor traffic through the tunnel.

IV. Replace the words in bold with others from the list.

explosives, construction, owing, affected, increase, tunnellers, conducted

The Mersey Tunnel in England belongs to the world’s longest underwater tunnels.Its building was carried out from the opposite sides of the river and the workers were to meet in the middle of the river beneath its bottom.

At first compressed-air drills were used for boring the tunnel, and the rate of construction was not very high. Later, however, tunneling was speeded up due to the application of charges.

When completed, the Mersey Tunnel became an important means of communication between the two towns because it permitted to considerably raise the flow of road traffic. In addition, the traffic was not influenced by weather conditions.

V. Correct the statements. The first example is made for you.

1. The Mersey Tunnel links Liverpool and Birmingham.

– Oh, no! You are wrong. The Mersey Tunnel connects Liverpool and Birkenhead.

2. The total length of this tunnel is over two and a half kilometres. 3. The work started on the Birkenhead side. 4. A system of ventilation left much to be desired. 5. Construction of the Mersey Tunnel lasted 6 years.

VI. Complete the diagram showing the construction of the Mersey Tunnel.

vertical shafts ______

enlarging of _____________

lining the tunnel

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VIII. Render the information about the Mersey Tunnel (one by one) using the following word-combinations:

The need is stresses to employ (подчеркивается необходимость использования)…; … is examined (исследуется)…; … is investigated (исследуется)…; … is analysed (анализируется)…; … is formulated (формулируется)…; attention is drawn to (обращается внимание на)…; data are given about (приведены данные о)…; attempts are made to analyse (делаются попытки проанализировать)… .

Home Exercises

I.Memorize the words from Ex. I page 135.

II. Open the brackets.

1. The tunnel near my house … this year (to build). 2. Most of the rivers … already … with canals (to connect). 3. The new methods of bridgework … good results (to bring). It is evident now. 4. France and Spain … from each other during the winter snows (to isolate). 5. What calculations … you … yourself and what … by your tutor (to do)?

Text 37 

I. The following information may be interesting for you. Read it and express the main idea.

TUNNELING COUCH OF THAMES

The National Research Development Corporation has backed an experiment contract awarded to Edmunds Nuttall, Sons and Co by the London Transport Executive. The 250000 contract is for the design and manufacture of a tunneling machine which will be based on a process patented six years ago by consulting engineers Mott, Hay an Anderson. This process involves the use of bentonite, under pressure, both to support the face and to remove spoil from the chamber.

It is hoped that if the experiment is successful the machine will be able to drive tunnel through the wet gravels in London, south of the Thames. This will enable the Underground System to be extended into the area which previously has not been feasible. The new Fleet Line, which has not yet been started, could partly cover the area.

The contract is expected to last about two years. The machine should be built within nine months by Nuttall’s subsidiary, Robert L. Priestley. It will be tested on a 600 ft length of tunnel, cast iron lined, which will be driven at New

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