ТОП 10:

Find in Text 9A the paragraph saying about land surveying and translate it into Russian.



Read aloud paragraphs 4 and 5 of Text 9A.

17. Find in Text 9A the definitions of the following terms and translate them into Russian:

 

a) surveying;

b) chains;

c) a compass;

d) an altimeter;

e) a levelling instrument;


 

f) calibrated circles;

g) a triangulation method.

 

Find in Text 9A some key words and expressions to speak about surveying techniques. Retell the Text in English.

19. Skim Text 9B "Land Surveying" and try to understand what it is about and what information is known to you.

• TEXT 9B

Land Surveying

The aim of cadastral surveys is to re-establish and mark the corners of original land boundaries. The first stage is to research relevant records such as land titles (deeds), survey monumentation (marks on the ground) and any public or private records that provide relevant data. The job of a boundary surveyor retracing a deed or prior survey is to locate such monuments and verify their correct position. Over time, development, vandalism and acts of nature often wreak havoc on monuments, so the boundary surveyor is often forced to consider other evidence such as fence locations, woodlines, monuments on the neighboring property, parole evidence and other evidence.

Monuments are the marks on the ground that define location. Pegs are commonly used to mark boundary corners. Small pegs in the ground and steel rods are used as instrument locations and reference marks, commonly called survey control. Marks should be durable and long lasting, stable so the marks do not move over time, safe from disturbance and safe to work at. The aim is to provide sufficient marks so some marks will remain for future re-establishment of boundaries. Examples of typical man-made monuments are steel rods, pipes or bars with plastic, aluminum or brass caps containing descriptive markings and often bearing the license number of the surveyor responsible for the establishment


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of such. The material and marking used on monuments placed to mark boundary corners are often subject to state laws/statutes.

A total station or GPS (Global Positioning System) is set-up over survey marks which were placed as part of a previous survey, or newly placed marks. The datum is established by measuring between points on a previous survey and a rotation is applied to orientate the new survey to correspond with the previous survey or a standard map grid. The data are analysed and comparisons are made with the existing records to determine evidence which can be used to establish boundary positions. The distance of lines between the boundary corners and total station positions are calculated and used to set out and mark the corners in the field. Checks are made by measuring directly between peg places using a flexible tape. Subdivision of land generally requires that the external boundary is re-established and marked using pegs, and the new internal boundaries are then marked. A plat (survey plan) and description (depending on local and state requirements) are compiled, the final report is lodged with the appropriate government office (often required by law), and copies are provided to the client.

Many properties have considerable problems with regards to improper bounding, miscalculations in past surveys, titles, and others. Also many properties are created from multiple divisions of a larger piece over the course of years, and with every additional division the risk of miscalculation increases. The result can be abutting properties not coinciding with adjacent parcels, resulting in gaps and overlaps. The art comes in when a surveyor must solve a puzzle using pieces that do not exactly fit together. In these cases the solution is based upon the research of the surveyor, and following established procedures for resolving discrepancies.

Give a brief overview of the structure and contents of Text 9B.


21. Complete the sentences choosing the best variant according
to Text 9B.

1)A boundary surveyor's job is

a) to mark the corners of the land boundaries desired by a customer.

b) to provide some relevant data.

c) to locate marks on the ground.

2) Pegs are used to

a) verify the boundaries.

b) locate boundaries.

c) make work safe.

3) To establish boundary positions

a) evidence of the existing records is used.

b) the distance between points on a previous survey is
measured.

c) the global positioning system is set up.

4) Checks are made by

a) marking the corners in the field.

b) measuring the distance between pegs.

c) subdividing land.

5) Many properties have problems regarding

a) abutting them.

b) multiple divisions of a land piece.

c) improper calculations.

22. Read Text 9C "Surveying Equipment" and answer the
questions. Discuss your answers with your groupmates.

a) Why is a theodolite regarded as a key surveying instrument?

b) What does a theodolite consist of?


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UNIT 9. SURVEYING I 209


 


 
 


c) What are both axes of a theodolite equipped with?

d) What is a horizontal axis error?

e) How is the sight axis determined?

f) Why are horizontal axis, collimation, and index errors taken

into account in the choice of the measurement procedure?

g) How is a theodolite adjusted?

h) How is a levelling instrument operated?

i) Why are self-levelling instruments preferred on sites?

j) What is a digital electronic level?

• TEXT 9C

Surveying Equipment

As late as the 1990s the basic tools used in planar surveying were a tape measure, a theodolite and a level.

A theodolite is an instrument for measuring both horizontal and vertical angles. It is a key tool in surveying and engineering work, particularly on inaccessible ground, but theodolites have been щ adapted for other specialized purposes in fields like meteorology and rocket launch technology. A modern theodolite consists of a movable telescope mounted within two perpendicular axes — the horizontal or trunnion, and the vertical axis. When the telescope is pointed at a desired object, the angle of each of these axes can be measured with great precision, typically on the scale of arcseconds.

An optical theodolite, manufactured in the Soviet Union in 1958 and used for topographic surveying.

Both axes of a theodolite are equipped with graduated circles that can be read out through magnifying lenses. The vertical circle should read 90° when the sight axis is horizontal, or 270° when the instrument is in its second


position, that is, turned over or plunged. Half of the difference between the two positions is called the index error.

The horizontal and vertical axes of a theodolite must be perpendicular. The condition where they deviate from perpendicularity and the amount by which they do is referred to as a horizontal axis error. The optical axis of the telescope, called the sight axis and defined by the optical center of the objective and the center of the crosshairs in its focal plane, must similarly be perpendicular to the horizontal axis. Any deviation from perpendicularity is the collimation error.

A horizontal axis error, a collimation error, and an index error are regularly determined by calibration and are removed by mechanical adjustment at the factory in case they grow large. Their existence is taken into account in the choice of the measurement procedure in order to eliminate their effect on the measurement results.

A theodolite is mounted on its tripod head by means of a forced centering plate containing four thumbscrews, or in some modern theodolites, three, for rapid levelling. Before its use, a theodolite must be placed precisely and vertically over the point to be measured — centering — and its vertical axis aligned with local gravity — levelling.

The level instrument is an optical instrument used in surveying and building to transfer, measure, or set horizontal levels. It is set up on a tripod and, depending on the type, either roughly or accurately set to a levelled condition using levelling screws. The operator looks through the eyepiece of the telescope while an assistant holds a tape measure or graduated staff vertical at the point under measurement.

The instrument and staff are used to gather and/or transfer elevations (levels) during site surveys or building construction. Measurement generally starts from a benchmark with known height determined by a previous survey, or an arbitrary point with an assumed height.


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An automatic level, self-levelling level or builder's auto level, includes an internal compensator mechanism (a swinging prism) that, when set close to level, automatically removes any remaining variation from level. This reduces the need to set the instrument truly level, as with a dumpy or tilting level. Self-levelling instruments are the preferred instrument on building sites, construction and surveying due to ease of use and rapid setup time. A digital electronic level is also set level on a tripod and reads a bar-coded staff using electronic laser methods. The height of the staff where the level beam crosses the staff is shown on a digital display. This type of level removes interpolation of graduation by a person, thus removing a source of error and increasing accuracy.

•*

SECTION 4 LISTENING AND SPEAKING

23. Listen to the Text "Surveying as a Career".

a) Answer the questions that follow.

1. What experts does civil engineering depend on?

2. What areas and structures are surveyors involved in?

3. What does a surveyor's work include?

4. What scientific knowledge must a surveyor have?

5. Should a surveyor be good at legal aspects in his work?

6. Should a surveyor be able to operate surveying instruments?

7. Why is surveying a distinct profession apart from engineering

in the USA?

8. What is required to get a qualification of a surveyor?

b) Check your answers with your groupmates and Tapescript 9A of the Text. Look up the words you do not know in the dictionary.

c) Retell the Text about a surveyor's responsibilities and duties.


d) Tell your groupmates about one of your relatives or friends working as a surveyor.

24. Listen to the Text "Modern Theodolites".

a) Complete the sentences according to the Text.

In today's theodolites, the____ of the horizontal and vertical

_______ is usually done_______ . The readout is done by a

rotary_______ , which can be absolute, e.g. using Gray codes,

or incremental, using_______ light and dark radial______ .

In the latter case the circles_______ rapidly, reducing angle

_______ to electronic_______ of time differences.

Additionally, lately computer-controlled___ sensors have

been added to the focal plane of the telescope__ both auto-
targeting and the_____ measurement of residual target offset.

All this is_______ in embedded software.

Also, many modern theodolites, costing up to___ apiece,

are_____________ with integrated electro-optical distance

measuring_______ , generally infrared based, allowing the

_______ in one go of complete______ vectors which can then

be________ to a pre-existing________ system in the area by

_______ of a sufficient number of control________ . This

_______ is called a resection solution or free station position

_______ and is widely used in__________ surveying. The

instruments, "intelligent" theodolites called___ tacheometers

or "total stations", . the necessary operations, _

data into internal registering units, or into external data___

devices. Typically, ruggedized____ are used as data collectors

for this_______ .

b) Check your answers with your groupmates and Tapescript 9B of the Text. Look up the words you do not know in the dictionary.

c) Retell the Text about theodolites.


UNIT 10


UNIT 10.FOUNDATIONS OF BUILDINGS 213


 


FOUNDATIONS OF BUILDINGS







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