The practice of control measurement is a concentrated practical teaching after the end of classroom study, which combines the content in the classroom with practice and deepens it, so our teacher arranged a folding scale practice. Control survey is to determine the horizontal position and elevation of a series of ground landmarks in a certain area according to the accuracy required by the survey task, and to establish a control network. Measuring the horizontal position of control points is called plane control survey, and measuring the height of control points is also called elevation control survey. Our task this time is divided into: traverse survey, triangulation and leveling. The first principle of measurement work is "control first, then break the parts." Therefore, control measurement is the basis of all kinds of measurement. Therefore, the teaching arrangement during the internship is an important link. Through the internship, we can not only understand the whole process of control measurement, systematically master the operation and calibration of instruments, and calculate at fixed points, but also lay the foundation for solving related problems in practical work in the future, and at the same time get a preliminary exercise in organization and practical work ability. In the internship, we have cultivated a rigorous and serious scientific attitude, a practical and realistic work style, a hard-working spirit and a collective concept of unity and cooperation. Although some differences of opinion were encountered on the way, through consultation, discussion, consulting relevant materials and the guidance of teachers, the problems encountered were not only solved, but also the cooperation ability was further improved. So we successfully completed this internship.

traverse survey

Traverse survey: a method of selecting a series of points on the ground to form a broken line, setting up measuring stations at these points, and then measuring the horizontal positions of these points by measuring edges and angles. Traverse survey is a method of establishing national geodetic control network and a common method of establishing control points in engineering survey. Therefore, the main tasks of traverse survey are: point selection, angle measurement, edge measurement and orientation.

Reconnaissance site selection and setting up signs

(1) First, determine the traverse according to the survey purpose, survey area size and surveying scale, then go to the survey area for reconnaissance, and determine the layout form of traverse according to the topographic conditions of the survey area. It is best to comprehensively consider the layout scheme in combination with the existing survey results.

After selecting traverse points, mark them on the ground. Generally speaking, stakes, nails and other marks are often used to mark points at the root of a map. After the points are calibrated, the points should be numbered uniformly, and the schematic diagram of the points should be drawn to facilitate finding points.

(2) Measurement of side length

The side length of conductor can be directly measured by rangefinder and total station, and can also be measured by steel ruler. If you use rangefinder and total station to measure, you should go back and forth once, and take the average value as the final result after meeting the accuracy requirements. When measuring, you can first measure the oblique distance, observe the vertical angle, and then correct it to the horizontal distance. You can also directly measure the horizontal distance.

If the steel tape is used for direct measurement, it should be measured twice in the same direction or once every round trip. For the root conductor, the relative error is less than or equal to 1/2000, and the average value is taken as the final result.

(3) Observe the horizontal angle

Using theodolite to measure the rotation angle of conductor. Different grades of wires and different types of instruments are used, so the number of test returns is different. DJ6 optical theodolite can be used to observe and measure root filament. The rotation angle of conductor can be divided into left angle and right angle. You can observe the left angle or the right angle. However, the left angle of the same wire should be determined as the left angle and the right angle should be determined as the right angle to avoid errors in calculating coordinates.

(4) Positioning:

1. Independent traverse: measure the azimuth of the starting edge with a compass.

2. When the wire is connected with the lead control point, the azimuth of the known edge shall be calculated by the coordinates of the known point.

The purpose of traverse measurement and calculation is to obtain the coordinates of each traverse point.

Steps:

Step 1: First, only the angle closure condition is considered. Angle closure difference should be "anti-sign average distribution".

Step 2: Calculate the coordinate increment of each side with the corrected angle value, and then calculate the coordinate closure difference.

Step 3: Only the X coordinate closure condition is considered. Invert the sign of the X coordinate closure difference according to the side length.

Coordinate increments assigned to each side of the ruler "

Step 4: Only consider the closing condition of Y coordinate. Specify the Y coordinate closure difference "Assign the inverse sign to the coordinate increment of each side proportional to the length of the side"

Coordinate calculation of closed traverse

1. Calculation and adjustment of angle closure difference The sum of internal angles of n sides should be: (n-2)* 180.

2. Calculation of coordinate azimuth of traverse edge. The relationship between the coordinate azimuth angles of two adjacent conductor edges in the same direction is or.

3. Coordinate increment between adjacent traverse points Calculation of coordinate increment: it is the difference between the coordinate values of two traverse points, that is, the coordinates from one traverse point to another traverse point.

4. Calculation and adjustment of coordinate incremental closure difference Theoretically, the algebraic sum of vertical and horizontal incremental closure differences should be equal to zero respectively.

levelling

Leveling is to measure the height difference between two points on the ground by using horizontal sight and leveling ruler, so as to calculate the elevation of unknown points from the elevation of known points.

The use of the level includes the steps of instrument placement, rough leveling, leveling, leveling and reading.

First, the level of resettlement

Open the tripod, make the height moderate, visually check whether the tripod legs are firmly placed and whether the tripod telescopic screws are tightened, then open the instrument box, take out the level, put it on the tripod head, and firmly connect the instrument with the tripod head with the connecting screws.

Second, rough leveling.

Rough leveling refers to making the vertical axis of the instrument approximately vertical with the help of bubbles in the circular level, thus making the collimation axis approximately horizontal. In the process of flattening, the moving direction of bubbles is the same as that of the left thumb.

Third, aim at the leveling staff.

First, aim the eyepiece at the light, that is, aim the telescope at the bright background, and rotate the eyepiece to make the reticle clear. Then loosen the brake screw, turn the telescope, aim the leveling rod with shutter and sight at the telescope tube, and tighten the brake screw. Then observe from the telescope; Rotate the objective lens, align the light screw to make the target clear, and then rotate the micro screw to align the vertical line with the leveling rod.

When the eyes move slightly up and down at the eyepiece, if the crosshair is found to have relative movement with the target image, this phenomenon is called parallax. The reason for parallax is that the plane of target imaging and the crosshair plane are not coincident. Because parallax will affect the correctness of reading, it must be eliminated. The way to eliminate it is to carefully aim the light at the objective lens again until the eyes move up and down and the reading remains unchanged. At this time, the image of the crosshair and the target seen from the eyepiece is very clear.

Fourth, the level of sophistication and reading

The eyes look at the bubbles in the leveling tube through the bubble observation window on the left side of the eyepiece, and the right hand turns the slightly inclined screw to make the images at both ends of the bubbles overlap, which means that the collimation axis of the leveling instrument is just horizontal. At this time, you can use the middle wire of the crosshair to read on the ruler. At present, most level meters use inverted telescopes, so the readings should be from small to large, that is, from top to bottom. Estimate the number of millimeters first, and then quote all the readings. Although leveling and reading are two different operation steps, they are regarded as a whole in the implementation of leveling. That is, after leveling, read again, and after reading, check whether the bubbles in the pipe level are completely consistent. Only in this way can we get accurate readings.

After the leveling field work is completed, consult the manual, and then calculate the height difference between points. After verification, the height difference and closure difference can be calculated and adjusted. Finally, the elevation of each point is calculated.

Verb (abbreviation of verb) technical requirements

(1) One-way second-class leveling observation records of not less than 3km (or 20 stations), and qualified observation results have been obtained.

(2) Checking and calculating the field observation results of leveling route and compiling the results table.

(3) Tolerance and technical requirements of second-class precision leveling:

Accidental average error

practical experience

Through this internship, we can consolidate, expand and deepen the theoretical knowledge learned in class. First of all, I understand the importance of controlling measurement. Since we want to measure, we can't do without practice. Practice is the best test of measurement knowledge. Just by listening in class, I don't have much specific knowledge, especially the use of musical instruments and the practical application of classroom knowledge. When I started the measurement on the first day, I was worried for a while: how to carry out the task. When you do it, it's not hard to find it. After listening to others or reading textbooks and then operating by yourself, you can basically master the method. If you want to improve the efficiency and measurement accuracy, you need to practice frequently, so that you can draw inferences from others. This knowledge is very important and basic.

Unity is strength and discipline is guarantee. It is far from enough for a measurement practice to be completely completed. Only the cooperation and unity of the group can make the exercise complete quickly and efficiently. This investigation practice has cultivated our team's ability of division of labor and cooperation, and enhanced the feelings between students. Our principle of completing this internship is to let every team member learn and practice knowledge, rather than rushing to make progress and call it a day. Therefore, each member of our team independently observes, records and accurately calculates each stop loss point. Step-by-step "inspection" can not only prevent error accumulation, find errors in time, but also improve measurement efficiency. We have a strict attitude. If you make a mistake, do it again, and never be careless. Until the measurement requirements are met. We know that in engineering, we need to be careful and rigorous. Through the joint efforts of each team member, we completed the measurement work.

After external measurement, it is necessary to come back for calculation and check whether the measurement results meet the requirements and are within the specified line difference.

Surveying practice, let me learn a lot of real things, and have the opportunity to comprehensively use the previous fragmentary surveying knowledge, which has well consolidated the theoretical teaching knowledge, improved the practical operation ability, and expanded the communication and cooperation ability with my classmates. Of course, there are many teachers' teaching and classmates' help. During this week, we also experienced many ups and downs, some of which were smooth or even zero error, and some of which hit a wall everywhere, but all of them passed and we finished the measurement happily. Although everyone is lazy in measuring, they don't want to measure.

I cherish the internship arranged by our school, which is an important link between theory and reality. Through practice, I not only learned the whole process of basic surveying and mapping, but also systematically mastered the basic skills of measuring instrument operation, measurement and calculation, which laid the foundation for future work. I also exercised my practical working ability. During my internship, I cultivated a work style that keeps pace with the times, a spirit of hard work and dedication, and a collective spirit of unity and cooperation.