Dredging ships. Практикум для СПО

UNIT III

BUCKET DREDGER

I. Pre-reading task

Exercise 1. Study the following words and word combinations.

self-propelled — самоходный ladder — зд. рама

capacity — вместимость, ёмкость chute — грунтоотводный лоток edge — край, лезвие

trench — ров, канава

enable — давать возможность

II. Reading activities

Exercise 2. Read the teхt.

Text

The bucket dredger is the oldest and best known type of dredgers. It is simple in operation. The hull is in most cases a rectangular pontoon. Demountable bucket dredgers have a main pontoon and a number of side pontoons. Some of the bucket dredgers are self-propelled. The bucket chain is mounted on the ladder, which is situated in the center of the main pontoon. The buckets are made of high-grade steel. The ladder can be lowered to the depth of 50 m or so. The bucket capacity varies between 200 and 1000 liters. The rotation of the chain brings the buckets to the top of the ladder, where the material is discharged into a chute and from there into barges. The barges may be moored on the port or starboard side of the dredger.

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The bucket dredger can operate in heavy soils, gravel and even rock. For the rocky bottom the buckets are fitted with toothed edges. This type of dredgers is suitable for a wide range of the tasks, including deepening of harbours, rivers and canals, excavating a trench for a pipeline or a tunnel.

During operation the dredger is held in position by means of six anchor wires. It is now possible to equip bucket dredgers with a buffer system to enable them to work in open water.

Exercise 3. Match parts of the sentences.

1.The hull is in most cases…

2.The bucket chain is mounted on the ladder…

3.The material is discharged…

4.This type of dredgers is suitable…

5.The dredger is held in position…

6.For the rocky bottom the buckets…

A.by means of six anchor wires.

B.into a chute and from there into barges.

C.is suitable for deepening of harbours, rivers and canals.

D.a rectangular pontoon.

E.which is situated in the center of the main pontoon.

F.are fitted with toothed edges.

III.Comprehension check

Exercise 4. Answer the questions.

1.What kind of hull do bucket dredgers have?

2.Where is the ladder situated?

3.What is the capacity of the buckets?

4.Where are the barges moored?

5.What is the range of tasks for bucket dredgers?

6.What are the buckets fitted with to operate on rocky bottom?

7.How is the dredger held in position?

8.What are the bucket dredgers equipped with to work in open waters.

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UNIT IV

GRAB DREDGER

I. Pre-reading task

Exercise 1. Study the following words and word combinations.

аlongside — вдоль quay — причал jaw — челюсть hinge — шарнир

output — производительность permit — позволять

increase — увеличить exeed — превышать

to be suited (to) — быть приспособленным (к) swell — качка

II. Reading activities

Exercise 2. Read the teхt.

Text

The grab dredger is one of the oldest and simpliest types of dredgers. They were developed in their present form in America. Grabs are ideal for working close alongside the quays and in places which can only be reached from a quay. Grab dredgers are used where the amount of excavation is relatively small. They consist of one or more grab buckets, operated by cranes. They can be mounted on other

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dredgers, on a pontoon or amphibious support or sometimes on the shore. Each bucket has jaws that are hinged together. The bucket is lowered to the bottom with its jaws open and pointing down. When it sinks into the material to be dredged, its jaws close. The material can then be lifted to the surface and discharged into a hopper for removal to a disposal area. They are suitable for a wide variety of soils. Their capacity is, however, limited, and modifications permiting high output are very expensive. On the other hand, the grab dredgers have the advantage that the dredging depth can be increased, virtually without limits. The grab can be positioned in both horisontal and vertical planes.It is important that additional means of transport are required if the horisontal distance exeeds the radius of the crane. The grab crane is fairly well suited to operating in swell.

Exercise 3. Rearrange words to make meaningful sentences.

1.support, can, mounted, on, be, a, dredgers, they, pontoon, or, on, ashore,or.

2.and,vertical, the,both, positioned, grab, horisontal ,be, planes, in, can.

3.alongside, are, for, ideal ,close, quays, grabs, working, the.

4.a, for, suitable, wide, are, variety, of, soils, they.

III. Comprehension check

Exercise 4. Answer the questions.

1.Where were the grab dredgers developed?

2.What are the advantages and disadvantages of grab dredgers?

3.In what case are additional means of transport required for grab dredgers?

Exercise 5. True or false?

1.The first grabs were brought to America.

2.Other dredger can serve as a support for the grab dredger.

3.Grabs have very high capacity.

4.The depth of dredging is very limited.

5.The additional means of transport is required when theradius of the crane is less then a horisontal distance.

6.Grab cranes are badly suited for operating in swell.

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IV. Grammar check

Exercise 6. Ask your friend if…

1.grabs were developed in America.

2.grabs are ideal for working alongside the quay.

3.grabs can be mounted on other dredgers.

4.grabs have an advantage that the dredging depth can be increased.

5.grab crane can be positioned in both horizontal and vertical planes.

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UNIT V

WHEEL DREDGERS

I. Pre-reading task

Exercise 1. Study the following words and word combinations.

cohesive — вязкий

boulder clay — валунная глина inlet — входное отверстие free-running sand — зыбучие пески to be subject (to) — подвергаться spillage — утечка

dredging wheel — роторный рыхлитель

swell compensator — волновой компенсатор (устройство для работы при волнении)

II. Reading activities

Exercise 2. Read the teхt.

Text

The weel dredger operates successfully in cohesive soils, even a boulder clay.The weel cuts the soil and transports it to the suction inlet.The weel derdger is broadly similar to the cutter dredger in terms of operation and the possibilities which it offers. However, it has a number of superior features:

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-precision dredging can be achieved in free-running sand;

-the spillage is considerably less than that of a cutter;

-unlike the cutter, the dredging wheel is not subject to blockage when working in coheive soil;

-the output of a wheel is more than that of a cutter.

Like the cutter dredger, the wheel is not suitable for operation in a swell, even if a swell compensator is installed. A possible disadvantage of a weel dredger is that it is more expensive than a cutter.

Exercise 3. Match the words with the nearest meanings.

III. Comprehension check

Exercise 4. Answer the questions.

1.What type of ground can a weel dredger successfully cope with?

2.What are the main advantages of this type of dredgers?

3.Does a swell compensator always help a weel dredger to work in open

water?

Exercise 5. True or false?

1.The spillage of a suction dredger is more than that of a wheel dredger.

2.A wheel dredger is cheeper than a suction dredger.

3.A wheel dredger can successfully operate in a swell.

4.A wheel dredger is often blocked in cohesive soils.

5.A wheel dredger cansuccessfully operate in free-running sand.

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IV. Grammar check

Exercise 6. Put the right prepositions.

1.The wheel dredger can operate … cohesive soils.

2.The wheel dredger is similar … the cutter dredger.

3.The dredging wheel is not subject … blockage.

4.The output … a wheel dredger is more than that … a cutter.

5.The wheel dredger is not suitable … operating … swell.

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UNIT VI

DIPPER DREDGERS

I. Pre-reading task

Exercise 1. Study the following words and word combinations.

dipper dredger — одночерпаковый штанговый земснаряд с прямой лопатой shovel — лопата

spud — свая

in conjunction (with) — в сочетании (с) rock-breaker — скалодробильный снаряд conventional — зд. oбычный

back-hoe dredger — одночерпаковый штанговый земснаряд с обратной лопатой

ditch — ров, канава draw — зд. тащить

II. Reading activities

Exercise 2. Read the teхt.

Text

A dipper dredger can best be described as a gigantic shovel, moved by mechanical or hydraulic means. Dredgers of this type are held in position by a spud and anchor wires, and can produce an accurate profile. As the dipper dredger is well suited

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to hard soil and can lift a great weight, it is often used in conjunction with a rockbreaker, its role then being to remove the fragment rock.

In addition to the conventional dipper dredger there is the back-hoe type. A back-hoe dredge has a back-hoe like on some excavators. A simple back-hoe dredger can be made by mounting a land-type back-hoe excavator on a pontoon. Small back-hoe dredgers can be track-mounted and work from the bank of ditches. A back-hoe dredger is equipped with a half-open bucket. The bucket is filled moving towards the machine. The dredged material is usually loaded in barges. This machine is mainly used in harbors and other shallow water. As the name indicates, the backhoe draws the soil towards itself, where as the dipper dredger moves it in the opposite direction.

Exercise 3. Rearrange words to make meaningful sentences.

1.described, can, dipper, be, a, gigantic, as, dredger, shovel, a.

2.by, dredgers, and, anchor, in, are, position, a, spud, dipper, wires, held.

3.type, with, a, it, of, is, dredgers, used, in, rock-breaker, conjunction, this, often.

4.backhoe, the, soil, towards, the, draws, itself.

5.the, moves, the, dredger, it, direction, opposite, dipper, in.

III. Comprehension check

Exercise 4. Answer the questions.

1.What is a dipper dredger?

2.How are dipper dredgers held in position?

3.What kind of profile can a dipper dredger produce?

4.What is the characteristic feature of a back-hoe dredger?

IV. Grammar check

Exercise 5. Put sentences into interrogative and negative forms.

1.A dipper dredger can be described as a shovel.

2.Dredgers of this type can produce an accurate profile.

3.A dipper dredger can lift a great weight.

4.The back-hoe type of dredgers can perform almost the same task as the dipper dredger.

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