Test points for the use of measuring instruments f

2022-10-24
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Knowledge points of water conservancy and hydropower Engineers: test points for the use of measuring instruments

[Abstract] universal school has sorted out "knowledge points of water conservancy and hydropower Engineers: test points for the use of measuring instruments", hoping to bring help to all candidates! For more simulated test questions and review materials, please continue to pay attention to the global school hydraulic and hydropower engineer examination channel

1f411041 be familiar with the use of measuring instruments

I. common measuring instruments and their functions

the commonly used measuring instruments in the construction of water conservancy and hydropower projects include level gauge, theodolite, electromagnetic wave rangefinder, total station, global positioning system (GPS), etc

(I) classification and function of level

level can be divided into ordinary level and precision level according to different accuracy. Domestic level can be divided into DS05, DS3, ds10, etc. according to accuracy. DS3 type ordinary level with slight inclination is generally used in engineering survey. D and s are the first letter of the Chinese phonetic alphabet of Geodesy and level respectively. The number 3 indicates the accuracy of the instrument, that is, the accidental mean square error of the mean value of the height difference of round-trip survey per kilometer is 3mm. In addition, there are automatic Anping level, digital level, etc

level is used for leveling. Leveling is to use a horizontal line of sight provided by the level to measure the height difference between two surface points with the help of a ruler with divisions, and then calculate the elevation of another point according to the measured height difference and the elevation of the known point

(II) classification and function of theodolites

theodolites can be divided into dj07, DJ1 and D. degradable high molecular materials need to have good compatibility J2, DJ6 and dj10 in all degradation processes. D and j are the first letter of Chinese phonetic alphabet of Geodesy and theodolite respectively, and the numbers 07, 1, 2, 6 and 10 indicate the accuracy of the instrument. According to different reading devices, it can be divided into two categories: micrometer reading devices; Single plate glass micrometer reading device

theodolite is the main instrument for angle measurement. It includes horizontal angle measurement and vertical right angle measurement. The horizontal angle is used to determine the plane position of the ground point, and the vertical right angle is used to determine the elevation of the ground point. In addition, the theodolite can also be used for sight distance measurement in low precision measurement

(III) classification and function of electromagnetic wave rangefinders

electromagnetic wave rangefinders can be divided into: Microwave rangefinders using radio waves in the microwave band as carriers; Laser rangefinder using laser as carrier; Infrared rangefinder using infrared light as carrier, and the latter two are collectively referred to as photoelectric rangefinder

electromagnetic wave rangefinder uses electromagnetic wave (light wave or microwave) as carrier to transmit ranging signal to measure the distance between two points. It is generally used for small area control survey, topographic survey, cadastral survey and engineering survey

(IV) total station and its role

total station is a set of automatic distance measurement, angle measurement, calculation and data automatic recording and transmission functions in one. 7. Cooler: the crud of air-cooled cooler should be cleared regularly; If water cooling is adopted, regularly inspect whether the cooling copper pipe has cracks and water leakage; Automatic, digital and intelligent three-dimensional coordinate measurement and positioning system

the function of the total station is to measure the horizontal angle, zenith distance (vertical right angle) and oblique distance. With the help of the software solidified in the machine, it can form a variety of measurement functions, such as calculating and displaying the horizontal distance, height difference and three-dimensional coordinates of the mirror station, and carrying out eccentric measurement, suspension height measurement, opposite side measurement, area calculation, etc

(V) global positioning system (GPS)

Global Positioning System (GPS) is a new generation of satellite navigation and positioning system with all-round real-time three-dimensional navigation and positioning capabilities in the sea, land and air. GPS has the remarkable characteristics of all-weather, high precision, automation, high efficiency and so on. It is widely used in geodesy, urban and mine control survey, building deformation survey, underwater topographic survey and so on

II. Use of common measuring instruments

(I) use of level

1 The use steps of the micro tilt level include placing the instrument and rough leveling (Rough leveling for short), focusing and aiming, precise leveling (fine leveling for short) and reading

(1) place the level and rough leveling. First select a flat and solid ground as the placement point of the level, then open the tripod to make it moderate in height, and the head of the tripod is roughly horizontal. Then fix the level on the head of the tripod with connecting screws, and step on the toes of the legs. Adjust the three foot screws so that the round level bubble is in the middle, which is called coarse level

(2) focusing and aiming. After leveling the level, point the telescope at the bright background and rotate the eyepiece focusing screw to make the crosshair clear; Aim the level ruler with the telescope's collimation and light door, and then tighten the brake screw to fix the telescope; Rotate the focusing screw of the objective lens, and then rotate the horizontal inching screw after the level ruler is clearly imaged, so that the vertical wire of the crosshair is aligned with the level ruler; After aiming at the target, the eye can move up and down at the eyepiece. If the crosshair is found to move relative to the target image, the reading changes with the movement of the eye, indicating parallax; The cause of parallax is that the target image does not coincide with the crosshair reticle, which will affect the accuracy of the reading; Parallax must be eliminated by first adjusting the eyepiece focusing screw to see the crosshair, and then continue to carefully rotate the objective focusing screw until the ruler image coincides with the crosshair plane

(3) fine leveling. Rotate the slightly inclined screw and observe the bubble observation window of the leveling tube at the same time. When it is consistent with the leveling bubble imaging, it indicates that it has been accurately leveled

(4) reading. When the bubble meets the level is in the middle, immediately read on the level ruler according to the middle wire of the crosshair. Whether the level used is positive or inverted, the reading is always read from the small end of the note to the large end. Usually, the reading keeps four digits

2. Operation procedure of precision level. It is basically the same as the general DS3 level, except that the precision level uses an optical micrometer to measure the value of less than one division. During operation, first rotate the slightly inclined screw to make the images at both ends of the bubble of the coincidence level tube on the left side of the telescope's field of view conform to ensure the level of line of sight. Turn the micrometer wheel again, so that the wedge wire on the cross wire accurately clamps the whole reticle, and read the reading of the reticle

3. Operation procedure of automatic level: rough leveling, collimation and reading

4. The operation procedure of digital level is basically the same as that of automatic Anping level, but the digital level can automatically observe and record, and display the measurement results in digital form

(II) use of theodolite

the use of theodolite includes four operation steps: alignment, leveling, collimation and reading

1. Centering and leveling

there are methods of vertical ball centering and theodolite leveling, and optical centering and theodolite leveling

(1) use the method of vertical ball alignment and theodolite leveling

● vertical ball alignment. First open the tripod and put it on the measuring station. The length of the tripod should be appropriate to facilitate observation; The tripod head should be roughly horizontal. Put the connecting screw on the tripod at the center of the head, hang the drop ball, move the tripod so that the tip of the drop ball is roughly aligned with the measuring station, and keep the head of the tripod roughly horizontal. Take the instrument out of the box and put it on the tripod. Screw the connecting screw to connect the instrument with the tripod. At this time, carefully observe whether the drop ball deviates from the center of the mark. If it deviates, slightly loosen the connecting screw, translate the instrument on the rack head, make the tip of the drop ball accurately align with the measuring station, and then tighten the connecting screw

● leveling. First, rotate the aiming part of the instrument so that the level tube is parallel to the spiral line of any two legs, and rotate the two legs to center the bubble; Then rotate the aiming part of the instrument by 90 and rotate the third foot screw to center the bubble. Repeat the above method several times until the instrument rotates to any position and the bubbles are centered

(2) use the method of optical aligner alignment and theodolite leveling

● visually evaluate the preliminary alignment, and make the tripod head roughly horizontal

● rotate and push and pull the centering device eyepiece to focus, so that the ground mark points are clearly imaged, and the central circle on the dividing board is also clearly visible

● rotate the screw of the instrument foot so that the image of the ground marking point is located in the center of the circle

● adjust the tripod legs to center the bubble of the circular level

● carry out accurate leveling according to the leveling method of household appliances such as refrigerators and televisions with drop balls

● check the optical aligner. At this time, if the mark point is located in the center of the circle, the alignment and leveling are completed. If there is still deviation, loosen the connecting screw slightly, move the instrument on the rack head to make it accurately align, and then carry out accurate leveling again until the average of the alignment and leveling meets the requirements

2. Aiming

(1) eyepiece focusing: turn the eyepiece focusing screw towards the bright background to make the crosshair clear

(2) coarse aiming at the target: loosen the horizontal and vertical brake screws of the telescope, aim at the target through the coarse sight on the telescope, and then tighten the brake screw on the horizontal and stable table

(3) objective lens focusing: rotate the focusing screw of the telescope objective lens to make the target image clear. Pay attention to eliminating parallax

(4) accurately aim at the target: rotate the horizontal micro motion and vertical micro motion spiral to make the crosshair vertical wire and the target imaging single line bisection or double wire clamping, and make the crosshair intersection part align with the bottom of the target

3. Reading

open the reflector, adjust its position, make the incoming light in the reading window bright and uniform, and then focus the reading microscope to make the divisions in the reading window clear for reading. The electronic theodolite can read directly on the screen

(III) use of electromagnetic wave rangefinder

1 In order to measure the distance d between point a and point B, first place the theodolite at point a, align and level it, and then place the rangefinder above the theodolite telescope

2. Place the reflector at point B

3. Aim the reflector

4. Set the unit, prism type and proportion correction switch in the required position

5. Distance measurement

6. In addition to the above ranging, the keyboard can also be used to calculate the horizontal distance, elevation difference and coordinate increment by inputting relevant data

(IV) use of total station

the setting out mode of total station has two functions, namely, measuring the setting out point and using the known coordinate data in the memory to set a new point. If the coordinate data is not stored in the memory, you can also enter the coordinates from the keyboard. The setting out steps are as follows:

1 Select a data collection file to store the collected data in it

2. Select the coordinate data file to call the coordinate data of the station and the rearview coordinate data

3. Set the test station

4. Set the rear viewpoint and determine the azimuth

5. Enter the required lofting coordinates to start lofting

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