What is the formula for third class leveling closure difference?

Excuse me. What is the formula for third-class leveling closure difference?

The allowable closure difference required by the "Three and Four Level Measurement Specifications" is:

1) Flat areas, 4 l mm (l is the length of the leveling route for round-trip measurements, joining, or loops, in "kilometers") 2) Mountainous areas, 12 hail drafts n mm (n is the number of stations).

The instrument used for leveling is a level, and the tools are a leveling rod and a ruler pad.

According to its accuracy, the level can be divided into five grades: DS05, DS1, DS2, DS3 and DS10. DS3 level is widely used in construction surveys.

Leveling is to use a horizontal line of sight and with the help of a leveling ruler to determine the height difference between two points on the ground, so that the elevation of an unknown point can be deduced from the elevation of a known point.

The permissible closure difference required by the "Code for Leveling of the Third and Fourth" is: (1) flat areas, 4 l mm (l is the length of the leveling route for round-trip measurement, joining or looping, in "kilometers") 2) mountainous areas, 12 n mm (n is the number of stations).

Leveling is also known as"Geometric leveling"It is a method of measuring the height difference between two points on the ground with a level and a leveling ruler. A level is placed between two points on the ground, and the level scale erected on the two points is observed, and the height difference between the two points is calculated according to the readings on the ruler.

According to the principle of leveling, the main function of the level is to provide a horizontal line of sight and can read according to the leveling scale. Therefore, the level consists of three main parts: the telescope, the level and the base.

1.Telescopes:

The DS3 level telescope is mainly composed of an objective lens, an eyepiece, a light lens and a cross-wire reticle. Objective lenses and eyepieces mostly use compound lens sets, and two long lines perpendicular to each other are engraved on the cross wire scribing plate, the vertical one is called the vertical wire, and the horizontal one is called the middle wire, which is used for aiming at the target and taking readings.

On the top and bottom of the vertical wire, there are also two short horizontal lines parallel to the middle wire, which are used to determine the distance, called the line-of-sight wire. The cross-wire reticle is made of flat glass discs mounted on a reticle base, which is fixed to the telescope tube.

The line between the intersection of the cross wire and the optical center of the objective is called the collimation or line of sight. Leveling is a reading on the level gauge with the midwire of the cross wire when the alignment axis is level.

Concave lenses allow targets at different distances to be imaged in the crosswire plane. Through the eyepiece, you can see both the magnified crosswire and the target image. The ratio of the angle of view of the image of the target seen from inside the telescope to the angle of view of the target directly with the naked eye is called the magnification of the telescope.

The magnification of a DS3 level telescope is generally 28x.

2.Level:

It is divided into a tube level and a round level, and the level is a device used to indicate whether the collimation axis is horizontal or whether the vertical axis of the instrument is vertical. There are two kinds of pipe level and round level. The tube level is used to indicate whether the collimation axis is level; The circular level is used to indicate whether the vertical axis is upright or not.

The formula for calculating the elevation difference closure of the fourth-class level measurement is 6 n or 20 l, and since the start and end points of the closed leveling route are the same elevation point, the elevation difference closure is equal to the sum of the elevation differences.

Fourth-class level measurement closure only search difference calculation method:

The algebraic sum of the sum of the altitude difference between the past and the back is not equal to zero, that is, the sum of the height difference between the past and back measurements h and the sum of the back altitude difference h should theoretically be equal to zero, but due to the influence of various errors in the measurement, the algebraic sum of the sum of the total height difference between the past and the return height difference is not equal to zero, that is, there is a height difference closure difference = cover mountain scatter h to + h back.

The closed horizontal route, because the starting point and the end point are the same point, constitute a closed loop, so the sum of the height difference of each measuring section measured by the closed horizontal route should theoretically be equal to zero, that is, h theory = 0Let the sum of the height difference of each measurement section actually measured by the closed level route be h, and the height difference closure difference = h measurement - h principle 3, and the attached level route.

Because the elevations of starting point A and end point B are known, the height difference between the two points is a fixed value, and the difference between the sum of the measured elevation difference of each measurement section of the attached level route and the theoretical value of the height difference is the height difference closure difference of the attached level route = h measurement - (HB-HA) When the height difference closure difference is within the allowable range, the height difference closure difference can be allocated.

The distribution principle is: for a closed or attached horizontal route, the height difference and closure difference are distributed by its sign according to the principle that it is proportional to the length of the route l or the number of stations n on the route. <>

1. If it is a closed wire, the theoretical height difference is 0, and the height difference closure difference is (measured height difference = the sum of the cumulative height difference of the horizontal line);

2. If it is a horizontal line, the height difference closure difference is the difference between (measured height difference = the sum of the cumulative height difference of the horizontal line) and (the difference between the theoretical height difference and the orange = the height difference of the starting point and the end point).

Wherein: measured height difference: h measurement = sum of the height difference between all adjacent points;

Known height difference: h known = h end - h beginning;

Closure Difference: H Closure = H Test - H Known.

<> subject can refer to the national standard "National.

The third and fourth level measurement specifications GBT 12898-2009, if you don't change the stove to the messy judgment, you can go to the public comprehensive Hao [standard housekeeper] by yourself**, the first and second level measurement specifications I also see the update, you can learn together.

Attachment level: Closure difference = Sum of elevation difference - (end elevation - starting point elevation) Closure level: Because the starting point and end point of the closed level route are the same elevation points of Zenyin Bridge, the elevation difference closure difference is equal to the sum of each elevation difference.

The total error per kilometer of elevation difference.

Less than 10mm; The length of the horizontal route is less than 16km; Use DS3 instrument and double-sided leveling ruler; with leveling points.

The joint test should be round-tripped once, and the loop or attached to it can be done once.

In the engineering survey code, the fourth-class level is measured.

l is the horizontal route length (km), which is the requirement for measurement on flat ground. If it is a mountainous area, calculate the allowable closure error, and n is the number of stations. When the closure error is within the allowable range, it is considered to have met the accuracy requirements.

Leveling. There are errors, and the measured height difference of the leveling measurement is often inconsistent with the theoretical value, and the difference becomes the closing error of the leveling route.

1.Closed Leveling Route: The algebraic sum of the height difference of the Closed Leveling Route should be zero. i.e. h理=0

Due to the error, the measured Gaoha synthesis is not cleared to zero, and the value is the height difference closure difference fh= h measurement.

2.Attached leveling route: The algebraic sum of the height difference of all measurement sections of the leveling route should theoretically be equal to the two known leveling points at the beginning and the end point.

height difference between them. i.e. h reason = h end - h beginning.

However, the measured height difference h-measure is not equal to h-reason, and the height difference is closed: fh= h-measure- h-reason=h-(h-end-h)

3.Branch level route: The branch level route should be measured back and forth, so theoretically, the sum of the height difference h to the distance and the sum of the height difference to the return test h to the end of the year.

Equal, the sign is reversed, the algebraic sum should be zero, so the height difference closure difference is fh = h back + h back.