Introduction to Surveying. Chapter -One-

Transcription

1 Introduction to Surveying Chapter -One- 1 GENERAL INFORMATION FALL 2016 Assistant Lecturer : Asmaa Abdulmajeed Research Assistant: Zanyar Bazyan Course Title : Surveying 1 Course Code : CE 215 Class No : S asmaa.abdulmajeed@ishik.edu.iq Office Hours : Thur. 14:00-16:00 Credit : 3 Lecture : 2 hrs Theory + 2 hrs Practical Website : Grade : 2 nd Year :

2 Required Textbook Surveying, Problem Solving with Theory and Objective Type Questions, by Dr. A. M. Chandra, Surveying with Construction Application, Barry F. Kavanagh, 7 th Edition, Prentice Hall, Recommended Reference Books The Principles of Surveying, by J. Clendinning, 2 nd Edition, Surveying Principles and Applications by Barry F. Kavanagh, 5th Edition, Prentice Hall, Engineering Surveying, by W. Schofield and M. Breach, 6 th Edition, Internet Sources. 3 GRADING POLICY Weekly Quizzes : 10% Assignments : 10% Reports : 10% Mid-term Exam : 30% Final Exam : 40% Assignments : Approximately (10) homework assignments will be given during the term. These assignments are very important. Their purpose is to promote your understanding of the course material, and to provide needed practice with example problems that are too lengthy to discuss in class. It is your responsibility to complete each homework assignment within one week of distribution. 4 2

3 Weekly Quizzes : Except for the week corresponding to the midterm, weekly quizzes will be given once per week, during the first fifteen minutes of lecture. In the Quiz, you will be expected to solve one of the questions from the previous week s subject (possibly with slight alterations in the numbers). The weekly quizzes will be completely closed book although calculators will be allowed. Midterms and Exam : One midterms will be scheduled in addition to the final examination. Midterm and the final exam will be closed book. You will also be allowed to use a non-communicating calculator. 5 Syllabus / Practical Survey 1. Ranging and linear distance measurement 2. Setting up level instrument 3. Level and leveling 4. Simple Leveling 5. Permanent adjustment of level 6. Differential leveling 7. Fly leveling 8. Reciprocal leveling 9. Profile and cross sectional leveling 10. Contour 6 3

4 Syllabus / Theoretical Survey 1. Introduction to surveying 2. Basics of surveying 3. Tape Correction 4. Distance Measurement 5. Leveling 6. Methods of levelling and their uses 7. Differential leveling 8. Fly leveling 9. Profile and cross section leveling 10. Contour 11. Area and Volume 7 CONTENTS CHAPTER -1- Surveying Fundamentals 1.1 Surveying Defined 1.2 Importance of Surveying to Civil Engineers 1.3 Objectives of Surveying 1.4 Types of Surveys 1.5 Classes of Surveys 1.6 Definitions 1.7 Surveying Instruments 1.8 Units of Measurement 1.9 Accuracy and Precision 1.10 Errors 1.11 Accuracy Ratio 1.12 Stationing 1.13 Types of Construction Projects 8 4

5 CHAPTER -1- BASICS OF SURVEYING 1.1 SURVEYING DEFINED What is surveying? Surveying is the art and science of determining the relative positions of various points or stations on the surface of the earth by measuring the horizontal and vertical distances, angles, and taking the details of these points and by preparing a map or plan to any suitable scale IMPORTANCE OF SURVEYING TO CIVIL ENGINEERS The planning and design of all Civil Engineering projects such as construction of highways, bridges, tunnels, dams etc. are based upon surveying measurements. Moreover, during execution, project of any magnitude is constructed along the lines and points established by surveying. Thus, surveying is a basic requirement for all Civil Engineering projects. Other principal works in which surveying is primarily utilized are : to fix the national and state boundaries; to chart coastlines, navigable streams and lakes; to establish control points; to execute hydrographic and oceanographic charting and mapping; and to prepare topographic map of land surface of the earth. 10 5

6 1.3 OBJECTIVES OF SURVEYING To select techniques, equipments for making decision; (Decision making). To collect field data; (Fieldwork). To prepare plan or map of the area surveyed; (Mapping). To analyze and to calculate the field parameters for setting out operation of actual engineering works. (Data processing) To set out field parameters at the site for further engineering works. (Reporting). 11 Why it is an art? Because only a surveyor who possesses through understanding of surveying techniques will be able to determine the most efficient methods required to obtain optimal results over a wide variety of surveying problems. Why it is scientific? Because the use of mathematical techniques to analyze field data, accuracy and reliability depends on understanding scientific principles underlying and affecting survey measurement. 12 6

7 What is measured? 1. Distances ; to calculate areas, volumes,etc.. to draw maps, plans, etc.. 2. Angles ; Both horizontal and vertical angles 3. Heights ; Levels or elevations 13 There are two types of surveying: 1. Plane (plain) surveying: 1.4 TYPES OF SURVEYING Earth surface is considered a plan of x-y dimensions. - Z-dimension (height) referenced to the mass spherical surface of the earth, mean sea level (MSL). - Most engineering and property survey are plane survey correction to curvature is made for long strips (Higher). 14 7

8 2. Geodetic surveying: Earth surface is considered spherical in resolution (actually ellipsoid) x-y. for - Z is referenced to MSL (surface of earth). -Very precise surveys (boundaries and coastal networks) CLASSES OF SURVEY a. Preliminary survey: (data gathering ) is the gathering of data (distances, position and angles) to locate physical features (rivers, roads, structures) so that data can be plotted to scale (map or plan), Preliminary surveys also include the determination of differences in elevation(vertical Distances) so that elevations and contours may also be plotted. b. Layout survey: Marking on the ground using sticks iron bar or concrete monuments. The features shown on a design plan features: - Property lines (subdivision survey). - Engineering work (construction survey). - Z-dimensions are given for x-y directions. 16 8

9 c. Control survey: used to reference prelim and layout surveys. d. Horizontal control: arbitrary line tied to prop line or HWY center or coordinated control stations. e. Vertical control: Benchmarks: points whose elev. above sea level is carefully determined. - In Control survey more care to accuracy. - Control lines should be easy to re-establish DEFINITIONS 1- Topographic survey: preliminary surveys used to tie earth surface features. 2- Hydrographic survey: preliminary surveys tie underwater feature to surface control line. 3- Route surveys: preliminary, layout and control surveys that range over a narrow but long strip of land (highways, railroads, electricity transmission lines and channels). 4- Property surveys: preliminary, layout and control surveys determine boundary locations for a new map. 5- Aerial survey: preliminary and final surveys convert aerial photograph into scale map using photogram metric tech. 6- Construction survey: layout of engineering work. 7- Final (as built) survey: preliminary surveys tie in features that just have been constructed 18 9

10 1.Topographic survey 2.Hydrographic survey 3.Route surveys 4.Property surveys 5.Aerial survey 6.Construction survey SURVEYING INSTRUMENTS 1. SURVEYING CHAIN The historical method for measuring distance is the surveying chain. One of the first chains used in the U.S. was the Gunter s chain. The Gunter s chain was a series of links attached to a handle which included an adjustment for wear. The chain was 22 yards (66 ft) long. In recent years surveyors have switched to plastic coated steel chains

11 MODERN CHAINS *Modern chains are metal strips 100 feet long. *Modern surveying chains are three standard types. Fully graduated First foot (cut chain) Extended foot (add chain) Assistant Lecturer/ Asmaa Ab. Mustafa 21 READING SURVEYING STEEL CHAIN The first step in reading a surveying chain is to determine the units that are used. Knowing that the chain is 100 feet long, having numbers from 0 to 100 indicates that each number is one foot of distance. Each foot has nine (9) lines (10 spaces), therefore each line represents 1/10 or 0.10 of a foot. The reading for this example is 98.6 ft. Note: this a fully graduated chain 22 11

12 READING A CUT CHAIN The first foot or cut chain gets its name from the fact that the whole foot reading at the head of the chain must be reduced cut by the partial foot. In this example the pin at the head is on 99 feet and the rear pin is on 0.4 feet. The distance is or 98.6 feet. 23 READING AN ADD CHAIN The extended foot (add) chain gets its name because an additional foot is added to each end of the chain. *The partial foot is added to the foot value at the head of the chain. *In this example the head pin is on 99 feet an the rear pin is at 0.7 feet. The distance is or 99.7 ft

13 2. STEEL CHAIN To rewind chain on holder: 1. Hold holder vertical in the left hand. 2. Attach 100 foot end of the tape with the numbers up. 3. Wind tape up rotating the handle clockwise. 4. Remember to wipe tape with a dry cloth as it is wound onto the handle ODOMETER WHEEL Insure you know the measuring units before you start to use the wheel. Odometer wheels use different units on the odometers. Assistant Lecturer/ Asmaa Ab. Mustafa 26 13

14 4. MEASURING WHEEL Distance Measuring Wheels are excellent tools for measuring long distances in a hurry. Some people call distance measuring wheels "footage wheels" or "distance calculation wheels". To use, simply reset the counter, place the wheel at the point you want to start measuring, and roll in a straight direction to the stopping point, then read the counter. Hence, the reason they are called a "Rolling Tape Measure" TAPING IN MEASURING Tapes are used for more accurate linear measurements in surveying and are classed according to the material of which they are made. TYPES OF TAPES A. Cloth or linen tape : Cloth tapes are made up of closely woven linen, 12 to 15 mm wide. Cloth tapes are used for taking rough measurements such as offsets. Cloth tapes are available in lengths of 10, 20, 25, and 30 meters and in 33, 50, 66, 100 ft.. Cloth tapes are light and flexible. They are used for taking rough measurements such as offsets. End of the tape is provided with a brass ring whose length is included in the total length of the tape. Cloth tapes are not used for accurate measurements because: 1)Length of cloth tape is gets altered by stretching. 2)Cloth tape is easy to twist and tangle. 3)Cloth tapes are not so strong. Assistant Lecturer/ Asmaa Ab. Mustafa 28 14

15 B. Metallic tape : A metallic tape is made of varnished strip of water proof linen interwoven with small brass, copper or bronze wires. Due to this tape does not stretch easily as a cloth tape. They are light in weight and flexible and are not easily broken. Metallic tapes are particularly useful in cross-sectioning and in some methods of topographical surveys where small errors in length of the tape are not given importance. Metallic tapes are manufactured in lengths of 2, 5, 10, 20, 30 and 50 meters. 29 C. Steel tape : A steel tape consists of a light strip of width 6 to 10 mm and is more accurately graduated as compared to cloth and metal tape. Steel tapes are available in lengths of 1, 2, 10, 20, 30 and 50 meters. Steel tapes vary in quality and in accuracy of graduation, but even a poor steel tape is generally more useful and accurate as compared to cloth or metallic tape. Steel tapes are wound on a corrosion resisting metal case with winding device. Steel tape is a delicate and light weight instrument hence it cannot withstand rough usage, should be cleaned, dried and oiled after use so that it does not get rusted

16 D. Invar tape : Invar tapes are available in lengths of 20, 30 and 100 meters. Invar tapes are used whey high degree of accuracy and precision in linear measurements is required such as measurement of base lines. Invar tapes are made of alloys of nickel and steel and have very low coefficient of thermal expansion. Invar tapes are more expensive as compared to other tapes. Main disadvantage of this tape is that it s length and coefficient of thermal expansion is not constant. It keeps changing with time. Therefore it is suggested to determine the length and coefficient of thermal expansion time to time TRANSIT Transits are the most versatile mechanical instrument. They are also the most complicated. Most have been supplanted by total stations. You might still see them in use

17 7. LEVEL Types of level: 1. Dumpy level 2. Tilting level 3. Automatic level 4. Digital auto level TILTING LEVEL 1. DUMPY LEVEL 3. AUTO LEVEL 4. DIGITAL LEVEL 34 17

18 5. THEODOLITE 6. TOTAL STATION 7. GPS RECIEVERS UNITS OF MEASUREMENT 36 18

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21 ACCURACY AND PRECISION Accuracy: is the relationship between the value of a measurement and the true value of the dimension being measured; the greater the accuracy, the smaller the error. Precision: describes the degree of refinement with which the measurement is made. For example, a distance measured four times with a steel tape by skilled personnel will be more precise than the same distance measured twice by unskilled personnel using a fiberglass tape

22 43 Example: True Dist. Meas. Dist. Error Cloth tape Steel tape Example: 44 22

23 Example; 45 Example; 46 23

24 Determine which of the crews is precise and accurate? 47 Solution ; 48 24

25 1.10 ERRORS What is error? An error is the difference between a measured, or observed, value and the true value. No measurement can be performed perfectly (except for counting), so every measurement must contain some error. Errors can be minimized to an acceptable level by the use of skilled techniques and appropriately precise equipment. For the purposes of calculating errors, the true value of a dimension is determined statistically after repeated measurements have been taken. Errors might be the cause of: -Imperfection in measuring instrument -Method of measurement -Natural factors - e.g. temperature, wind, rain -Random variations in human observation 49 Types of Errors in Surveying 1. Systematic errors: are defined as those errors for which the magnitude and the algebraic sign can be determined. The fact that these errors can be determined allows the surveyor to eliminate them from the measurements and thus further improve accuracy. An example of a systematic error is the effect of temperature on a steel tape. If the temperature is quite warm, the steel expands, and thus the tape is longer than normal. For example, at 83 F, a 100-ft steel tape can expand to ft, a systematic error of 0.01 ft. Knowing this error, the surveyor can simply subtract 0.01 ft each time the full tape is used at that temperature

26 2. Random errors: are associated with the skill and vigilance of the surveyor. Random errors (also known as accidental errors) are introduced into each measurement mainly because no human can perform perfectly. Random errors can be illustrated by the following example. Example ; such as reading 9.64 instead of 6.94, writing 5.45 instead of 4.54 They are preventable; Follow standard procedures Know how to use equipment Always check your work; use independent ways to check your works ACCURACY RATIO The accuracy ratio of a measurement or a series of measurements is the ratio of the error of closure to the distance measured. To illustrate, a distance is measured and found to be ft. The distance was previously known to be ft. The error is 0.05 ft in a distance of ft: Accuracy ratio: Ratio of error of closure to the distance measured Exp. measured dist known dist error Accuracy ratio Typical ratio: 1/3000, 1/5000, 1/10,000, 1/20,000 Assistant Lecturer/ Asmaa Ab. Mustafa 52 26

27 1.12 STATIONING While surveying, measurements are often taken along a baseline and at right angles to that baseline. Distances along a baseline are referred to as stations or chainages, and distances at right angles to the baseline (offset distances) are simple dimensions. The beginning of the survey baseline the zero end is denoted as ; Example: a point 100 ft (m) from the zero end is denoted as ; a point ft (m) from the zero end is ; and so on. In the preceding discussion, the full stations are at 100-ft (m) intervals, and the half stations are at even 50-ft (m) intervals. Twenty-meter intervals are often used as the key partial station in the metric system for preliminary and construction surveys. With the ongoing changeover to metric units, most municipalities have kept the 100-unit station (i.e., = 100 m), whereas highway agencies have adopted the 1,000-unit station (i.e., = 1,000 m). Example: , 555.5, , use 100 unit stations

28 1.13 TYPES OF CONSTRUCTION PROJECTS Listed below are the types of construction projects that depend a great deal on the construction surveyor or engineering surveyor for the successful completion of the project: 55 28