How to eliminate the influence of I angle of level on the observation value of height difference in measurement

If the level is uneven, everything is empty talk. Let's see how to train first. The following figure shows how to level the elevation.

First, adjust the length of the three legs according to the terrain, so that the level is roughly horizontal. Then step on any two feet, leaving one movable for easy adjustment. The relationship between the moving direction of the leg and the moving direction of the circular bubble is shown in the above figure. Note: If the ground is soft, stepping on the last leg will appear in the lower right of the figure, so leave a certain margin. After all three legs are stamped, adjust the three screws and adjust the round bulb to the middle. The relationship between the rotation of the spiral and the motion of the circular bubble is as follows:

After the round bubble is adjusted, if it is an automatic level, it can be read directly. If it is semi-automatic, just press a button. If you need to adjust the length of the bubble, it will be a bit troublesome. Flatten the long bubble and read it again. The more symmetrical the two sides of the U-shaped bubble, the better.

Section II Level 1 Data

There is nothing to say about reading. As long as you can read the ruler, you should be able to read it. The key is the precision of the last digit (mm). One thing to note is that when the tower ruler is erected, it will tilt slightly (it may not be visible to the naked eye), which will lead to a large reading, so when I am not sure, I personally tend to make the reading smaller. For example, it looks like 1456.5, and I will read it as 1456 instead of 1457 (the correct reading should be

The basic formula for using a level is:

Reading+Height = Instrument Height

Once the instrument is erected, its instrument height will not change, and after the instrument is erected, a leveling point is needed. The so-called leveling point is a point with elevation information. By reading the reading of this point and adding the elevation of this point, the total is the height of the instrument.

Leveling point elevation+leveling point reading = instrument height

In the construction process of controlling each floor structure with leveling lens, there are the following formulas:

Instrument height = target point height+target point reading

From the above two formulas, the following formulas can be obtained:

Leveling point elevation+leveling point reading = instrument height = target point elevation+target point reading

This formula is used in the construction process. The picture shows the schematic diagram of each part. Among them, two data of the leveling point are known, and the elevation of the target point is known. As long as the reading of the target point can reach the calculated value, the actual elevation of the target point conforms to its theoretical value.

In practical work, you will encounter the opposite process. For example: first, both readings are actually read, and then the elevation of the target point will change with the elevation of the leveling point, that is, the elevation of the leveling point will increase, and vice versa; Secondly, when the elevation of the leveling point cannot be changed but the reading can be changed, the actual reading of the target point will change the same as the elevation of the target point. If you are confused, please remember the following points: the target point reading is actually read, and the target point elevation changes with the height of the instrument. If you want to change the height of the target point, you just need to find a way to make the height of the instrument change the same. In addition, there may be some other situations that can be solved as long as you remember the above formula and deal with it flexibly according to the situation at that time.

There is also a special case: the ruler used for measurement may be half long, that is, the number at the bottom of the ruler is not 0, but other data. Then the formula will change:

Reference elevation+leveling point reading+foot bottom = instrument height+foot bottom = target point elevation+target point reading+foot bottom.

It can be seen that in this case, as long as the same ruler is used before and after, there will be no problem.

Sometimes only the height difference between the leveling point and the target point is known, and the target point is both a leveling point and a reference point. At this time, just change the formula.

Level point elevation-target point elevation = target point reading-level point reading

Calculation of target elevation points in the third quarter

The so-called target elevation points are mostly the design elevation or the data calculated according to the design elevation. Please look at the following two formulas:

Elevation of target point = design elevation-structural layer thickness-transverse slope × distance of target point from road.

Target point reading = instrument height-design elevation+structural layer thickness+cross slope × distance from target point to road.

Pay attention to the direction of the cross slope. In most cases, the middle of the road is high and the sides are low, but there are also the opposite situations, such as ultra-high sections or individual designs (for example, the middle of Dongli Lake Scenic Avenue is low and the sides are high to collect rainwater into the middle green belt).

The fourth quarter leveling point layout

Leveling point is the premise of all leveling work, and poor leveling point will affect the construction quality of the whole road. Under normal circumstances, before a project starts, the design unit will hand over important points such as leveling points, traverse points and road midpoint to the construction unit, commonly known as "pile delivery". These points are often not enough for construction and need to be encrypted, including leveling points and traverse points. This section only discusses the layout of leveling points.

First of all, the location of the leveling points should be selected within the scope of the whole line and recorded. Note: No matter what work you do, when it comes to the process of setting up points, you should remember to "note". The principle of selecting leveling points is: the points should be fixed. At least it will not be lost during construction. I usually choose to hammer nails on steps, low walls or trees when I work. Attention should also be paid to site selection. Try to choose the direction facing the road, and also pay attention to ensure that the ruler is upright. For example, when nailing a nail in a tree, you should choose those trees that are crooked outside the road. When erecting a ruler, don't lean the ruler against the tree, because the seemingly vertical tree is not upright from the leveling mirror. The selected points should be numbered and recorded in this book. This book is very important. Most of the previous survey results are recorded in a book, one for each project. Don't be confused. The leveling points set should be able to cover the whole construction scope of this project. The coverage of a point is a circle with the center of the point and the radius of 150m.

After the point is set, the next step is measurement. This work is best done by five people: two hands, two looking at the level, and one recording and calculating the data in real time. All leveling points and head and tail points should be known points, that is, the points given by the designer when handing in piles. Measuring the height difference between two adjacent points is a station. A project has n leveling points. When measuring these points, there will be n- 1 stations. The point in the incoming direction of each station is the rear viewpoint, and the point in the forward direction is the front viewpoint. The workflow of each station is as follows:

First, the tower ruler should be set at the front and rear viewpoints. The person who looks at the head-up glasses should set the head-up glasses at a place where the difference between the front and rear sight distances can be within 5m, so as to minimize the error caused by the vertical angle of the head-up glasses (the front and rear sight distances can be obtained by reading the numerical difference between the upper and lower wires of the front and rear viewpoints respectively, and the reading difference between the upper and lower wires and the actual distance is 1: 100, that is, the reading difference is 1cm.

Second, two people read the front and back readings respectively, and then subtract the front data from the back data respectively, and the result is the height difference between the front viewpoint and the back viewpoint. The formula is as follows:

Rear view reading-forward view reading = elevation difference between front and rear points = elevation of front view point-elevation of rear view point.

After reading the results, the difference between them is within 3mm, so it is ok to enter the next station for observation. If it is greater than 3mm, adjust and re-observe it until the data meets the requirements. Do not resort to deceit. The contents of the adjustment include: repositioning the vertical mirror, re-erecting the mirror, and changing the mirror readings by two people.

It should be noted that some books require that the vertical height difference between two level glasses should be greater than 10cm. Personally, I don't think it is necessary, because the requirement is to separate the data, which means that the correct values can be obtained from different vertical heights. I think as long as the data is correct.

When the work of all stations is completed, the next step is adjustment, and its principle is as follows:

One, assuming that there is no error in the measurement process, there is the following formula:

Elevation of the first bench mark+elevation difference of the first station +...+n- 1 elevation difference of the station = elevation of the nth bench mark.

Second, after considering the error, the formula is as follows:

Elevation of the first leveling point+

(first station height difference+first station error) +...+(N- 1 station height difference +N- 1 station error)

= elevation of the nth leveling point +n- 1 sum of errors of each station.

Thirdly, the purpose of adjustment is to eliminate all errors of the second formula and make the second formula become the first formula. Of course, this is only theoretically eliminated for the smooth progress of the work, and the actual error will not be eliminated.

The adjustment method is as follows: in the second formula, "n- 1 sum of station errors" is subtracted from the right side of the equal sign, and "n- 1 one-tenth of the sum of station errors" is subtracted from each station on the left side of the equal sign, as shown in the following figure:

Elevation of the first bench mark+(head station elevation difference+head station error -(n- 1 sum of station errors) /n)+ ...

+(height difference of n-1station+error of n-1station-(sum of errors of n-1station) /n)

= elevation of the nth leveling point +n- 1 sum of errors of each station -n- 1 sum of errors of each station.

already

Elevation of the first bench mark+(head station elevation difference+head station error -(n- 1 sum of station errors) /n)+ ...

+(N- 1 station elevation difference +N- 1 station error -(N- 1 sum of station errors) /n) = elevation of the nth bench mark.

It should be noted that, strictly speaking, the adjustment of each station should not be the sum of simple average errors, but the greater the distance between stations, the more adjustment times. The above formula is just a simple algorithm. Personally, I think it can be used as long as the accuracy allows, because the accuracy of construction survey is not entirely in the setting of leveling points, and it is useless to be inaccurate in actual construction. Please refer to the specifications for the construction accuracy, and the leveling points can meet the specifications, so there is no need to keep improving. Construction pays attention to both accuracy and speed, and cannot be biased towards one side. The key is balance and sufficiency. In addition, the distance adjustment formula with the measured station is attached:

Elevation of the first leveling point+

(First station height difference+first station error -(n- 1 sum of station errors) × (first station distance /n- 1 total station distance))

+ …… +

(N- 1 height difference of station +N- 1 error of station-(sum of errors of n-1station) ×(N- 1 distance of station/n-/total distance of station))

= elevation of the nth leveling point

After adjustment, the next thing to do is to calculate the elevation of each leveling point according to the adjustment result, and the formula is as follows:

The elevation of the second leveling point = the elevation of the first leveling point+the elevation difference of the first station.

Elevation of the third leveling point = elevation of the second leveling point+elevation difference of the second station.

etc

Elevation of the nth leveling point = elevation of the nth leveling point+elevation of the 0th leveling point+elevation difference of the nth station +0.

Note: this height difference is the adjusted height difference, not the result of direct reading, which is different from the above and below.

At this point, the leveling part of the measurement is basically completed. Please forgive me if there are any omissions. I attach an automatic adjustment leveling table compiled by excel, which I hope will be helpful to you.

Attached Table: Automatic Calculation Table for Leveling Adjustment

A B C D E

After height adjustment 1 point reading height difference elevation

2s13333 = b2-b3 = c2-d32/c32s1elevation.

3 s2 3333 =E2+D2

4 3333 =B4-B5 =C4-D32/C32

5 s3 3333 =E3+D4

6 3333 =B6-B7 =C6-D32/C32

7 s4 3333 =E5+D6

8 3333 =B8-B9 =C8-D32/C32

9 s5 3333 =E7+D8

10 3333 = b 10-b 1 1 = c 10-D32/C32

1 1 S6 3333 = E9+d 10

12 3333 = b 12-b 13 = c 12-D32/C32

13 S7 3333 = e 1 1+d 12

14 3333 = b 14-b 15 = c 14-D32/C32

15 S8 3333 = e 13+d 14

16 3333 = b 16-b 17 = c 16-D32/C32

17 S9 3333 = e 15+d 16

18 3333 = b 18-b 19 = c 18-D32/C32

19s 10 3333 = e 17+d 18

20 3333 = B20-b 2 1 = C20-D32/C32

2 1s 1 13333 = e 19+D20

22 3333 =B22-B23 =C22-D32/C32

23 s 12 3333 =E2 1+D22

24 3333 =B24-B25 =C24-D32/C32

25 s 13 3333 =E23+D24

26 3333 =B26-B27 =C26-D32/C32

27 s 14 3333 =E25+D26

28 3333 =B28-B29 =C28-D32/C32

29 s 15 3333 3333 =E27+D28

30 = Sum (C2:C29)= Sum (D2:D29)

3 1 s 1 elevation s 15 elevation =B3 1-A3 1.

32 = Count (C2:C29) =C30-C3 1

Table description: 1, the outermost numbers and letters represent the line numbers and column numbers in EXCEL, and cells are represented by the formula of column number plus line number, for example: A 1, B 19, E32.

2. A cell formed by merging two cells, whose expression is based on the upper left cell of the cell, for example, C24, without C25.

3. The coarse grid in the table should be filled in according to the actual situation, which is known data.

4. The part with equal sign is the calculation formula. In EXCEL, it will output and copy the calculation results.

5. Write a list of "3333" for reading and fill it in according to the actual situation.

6. Write numbers by dots. In the actual process, the top line of Chinese characters can be copied.

7.SUM(C2:C29) means to calculate the sum of the values of cells C2 to C29.

8.COUNT(C2:C29) is used to calculate the number of non-empty cells from C2 to C29, which is 14 in this example.

The third plane survey

The second article is about leveling, which is vertical and one-dimensional. This article is about plane measurement. The plane is horizontal and two-dimensional. The function of plane survey is to make the plane shape of the actual road conform to the drawing. At present, the plane survey is mainly carried out by total station, and the accuracy and speed of GPS can only be one of them. As mentioned earlier, there must be a balance between accuracy and speed, and the total station is the tool that most conforms to this principle at present.

Section 1 Total Station Leveling

As the total station is a two-dimensional measuring tool, its leveling has two requirements: "levelness" and "centering". There are two horizontal bubbles in the total station, one is a round bubble and the other is a long bubble. The final state of leveling should be: no matter which direction the total station faces, the long bubble should remain horizontal, and the vertical mirror point is exactly in the center of the mirror when viewed from the centering mirror.

Total station leveling steps are as follows:

First, according to the terrain around the vertical mirror point and your height, adjust the length of the three legs of the tripod. Firstly, the center of the total station is roughly opposite to the vertical mirror point, and the upper plane of the tripod is basically horizontal. And step on three legs and adjust.

2. Adjust according to the relationship between the leg length of the tripod, the three angular spirals of the total station, the position of the point in the centering mirror and the position of the circular bubble as shown in the figure below. The law is simple, as long as the combination is flexible, we can achieve our goal.

3. When the circular bubble is flat, if the neutral mirror point in the centering mirror is not too far from the center, you can unscrew the bolt that fixes the total station on the tripod (just unscrew it, don't separate it) and move the total station to the center. At this time, the angle screw is used to adjust the long bubbles. The method is to rotate the total station to make the long bubble parallel to the connecting line of any two angle screws, and then level the long bubble. Then rotate the total station by 90 degrees to make the long bubbles perpendicular to the original direction, and then just adjust another angle screw to level the long bubbles. At this time, it is basically satisfied that long bubbles are flat at any angle. Then move the total station to the center, adjust the length of the bubble, and repeat these two contents until the levelness and alignment are satisfactory.