GB 12897-1991 National first and second class level measurement specifications
Some standard content:
National Standard of the People's Republic of China
National first and second order leveling specifications
Specifications for the first and second order leveling1 Subject content and scope of application
GB12897-91
This standard specifies the layout principles, survey methods and accuracy indicators for the establishment of first and second order leveling networks on the national territory. This standard is applicable to the layout of the first and second order leveling networks of the country. It can also be used as a reference for regional precision leveling. 2 Reference standards
GB3160 Leveling instrument series and basic parameters
GB3161 Theodolite series and basic parameters
3 Terms
Leveling points in a node leveling network that connect at least three leveling lines. Leveling route A leveling line between two adjacent nodes in a leveling network of the same level. A leveling line between two adjacent basic leveling points in a section leveling route. Survey section
Continuous survey
Support survey
Connection survey
Test
Re-survey
Re-survey
Leveling line between two adjacent leveling points.
Observation of leveling points or other elevation points included in the leveling route. Leveling measurement from any leveling point in the route to triangulation points, traverse points, hydrological stations and any other fixed points. Observation of connecting any point in the newly established leveling route to leveling points on other routes. Observation to check whether the change in the measured height difference exceeds the regulations. Observation to be re-conducted because the quality of the results does not meet the specifications. Measurement of the measured leveling route at regular intervals. 4 Layout of leveling network
4.1 Layout principles
4.1.1 The first-class leveling route should be laid out along the traffic route with a gentle road slope and not too busy traffic. The leveling route should generally be closed into a loop and form a network. The circumference of the first-class leveling loop should be between 1000 and 1500 km in plain and hilly areas; it should be around 2000 km in mountainous areas, and it can be appropriately adjusted according to specific conditions in difficult areas. 4.1.2 The first-class leveling network is re-surveyed every 15 to 20 years. 4.1.3 The second-class leveling network is laid out within the first-class leveling loop. The second-class leveling route is laid out along highways, roads and rivers as much as possible. The circumference of the second-class leveling loop should be between 500 and 750 km in plain and hilly areas; it can be relaxed according to specific conditions in mountainous areas and difficult areas. 4.1.4 The tidal station benchmark points, settlement observation benchmark points in cities and industrial areas, and crustal deformation observation benchmark points near the leveling route should be included in the leveling route for continuous measurement. If continuous measurement is indeed difficult, it can be measured by support. The measurement level is the same as the level of the route. The large-scale locations, hydrological points, meteorological stations, etc. near the route (hereinafter collectively referred to as "other fixed points") can be included in the route for continuous measurement or support measurement as needed. The survey level of the branch line can be determined according to the requirements of the user unit. If there is no special accuracy requirement, when the branch line length is within 20km, it shall be surveyed according to the fourth-class leveling accuracy; when the branch line length is 20-50km, it shall be surveyed according to the third-class leveling accuracy; when the branch line length is more than 50km, it shall be surveyed according to the second-class leveling accuracy.
4.2 Leveling point layout density
On the leveling route, stable leveling points should be buried at a certain distance. Leveling points are divided into three types: bedrock leveling points, basic leveling points, and ordinary leveling points. The spacing and layout requirements of various leveling points should be implemented according to the provisions of Table 1. Table 1
Leveling point
Type
Bedrock
Leveling point
Basic
Leveling point
Ordinary
Leveling point
Spacing
About 500km
About 40km20
~30km in economically developed areas; about 60km in desert areas
Right
4~~8km; 2~4
km in economically developed areas; about 10km in desert areas
4.3 Route naming and leveling point numbering
Layout requirements
Only set up on first-class leveling routes, and should be added near large cities and ground-attack zones. The spacing can be appropriately relaxed in areas with deeper bedrock. Each province (municipality, autonomous region) shall have at least two first- and second-class leveling routes and their intersections, on both sides of large and medium-sized cities and near county towns. The leveling points shall be set up in the hard rock layer
at the location where the ground is stable and conducive to observation and long-term preservation, near the elevation change point of the leveling route in mountainous areas; at both ends of a tunnel with a length of more than 300m; near the scale points on both sides of the river for cross-river leveling
4.3.1 The leveling route is named by the abbreviation of the starting and ending place names, and the order of the starting and ending place names is "starting from the west and ending in the east", "starting from the north and ending in the south". The grades of the first and second-class leveling routes are indicated by I and II before the line name. 4.3.2 The leveling points on the route shall be numbered in the order of 1, 2, 3, etc., starting from the starting leveling point of the line. 4.3.3 In addition to being numbered according to the above regulations, the bedrock leveling points shall also be numbered with the place name and the three words "bedrock point" before the name. 4.3.4 The basic leveling point shall be written with the word "base" after the number, and the superscript and subscript shall be written with the words "upper" and "lower" respectively. 4.3.5 The leveling branch line shall be named after the name of the height point it measures with the word "branch". The leveling points on the branch line shall be numbered in the order of 1, 2, 3, etc. from the starting leveling point to the measured height point. 4.3.6 When using old leveling points, the old names may be used. If re-edited, the old name of the point when it was buried shall be indicated in brackets after the new name.
4.4 Connection between the newly established route and the measured route
4.4.1 The starting point and end point of the newly established first- and second-class leveling route shall be the basic leveling points or bedrock leveling points of the measured high-level or equal-level routes. When the end point cannot be connected to the measured route temporarily, the future connecting route shall be estimated. 4.4.2 When a newly established leveling route passes through or approaches a first- or second-class leveling point that has been measured within 4km, or is within 1km from a third- or fourth-class leveling point that has been measured, it should be measured continuously or connected. When connecting, the measured leveling points must be tested according to the provisions of Article 7.10. 4.4.3 For connecting the leveling points on the measured route, the measurement shall be carried out according to the accuracy requirements of the new route and the measured route, whichever is lower. 4.4.4 When a newly established leveling route coincides with an already measured leveling route, the old points should be used as much as possible. When the stability of the old points is in doubt or the specifications of the old point markers do not meet the requirements, the markers should be re-buried, but the old points must be continuously measured. 4.5 Gravity measurement on the leveling route
4.5.1 In areas with an elevation greater than 4000m or an average height difference of 150 to 250m between leveling points, gravity should be measured for each leveling point on the first- and second-class leveling routes. For the survey section with elevation difference greater than 250m, gravity measurement shall be added at the place where the ground tilt changes. 4.5.2 In areas with elevation between 1500～4000m or average elevation difference between leveling points of 50～150m, the average distance between gravity points on the first-class leveling route shall be less than 11km; on the second-class leveling route, it shall be less than 23km. 4.5.3 In the northwest, southwest and northeast border areas, gravity shall be measured at each leveling point on the first-class leveling route. 4.5.4 Gravity shall be measured point by point on the first-class leveling route from Qingdao leveling origin to the national geodetic origin. 4.5.5 Gravity measurement on leveling points shall be carried out according to the requirements for dense gravity points. 4.6 Elevation system and elevation datum
GB12897-91
The elevation of leveling points adopts the normal height system and is calculated according to the 1985 national elevation datum. The elevation of Qingdao origin is 72.260m. When an offshore island cannot be directly connected to the national elevation network, a local leveling origin can be established, and its elevation can be determined based on the observation of the average sea level at the tide gauge station on the island, which serves as the elevation benchmark for the island and its nearby islands. The elevation of any leveling point measured using a local leveling origin should be indicated in the leveling point results table, and the relevant information of the local elevation benchmark should be explained. 4.7 Accuracy of leveling measurement
The accidental mean error M of leveling measurement per kilometer and the total mean error Mw of leveling measurement per kilometer should generally not exceed the values ??specified in Table 2.
Table 2
Grade
M
Mw
First
0.45
1.0
M. The calculation method of Mw is specified in Articles 9.5.3 and 9.5.4. 4.8 Technical design of leveling network
etc
1.0
2.0
mm
Before laying out the leveling network, technical design must be carried out to obtain the best layout plan for the leveling network and leveling route. The requirements, contents and approval procedures of technical design shall be implemented in accordance with ZDA75001 "Surveying and Mapping Technical Design Regulations". 5 Point selection and stone burial
5.1 Point selection
5.1.1 The selected leveling route
should be carried out along roads and highways with smaller slopes as much as possible; a.
b.Areas with soft soil and areas with strong magnetic fields should be avoided; streets with a lot of pedestrians and vehicles and large railway stations should be avoided; c.
d.
Rivers, lakes, swamps, canyons and other obstacles: e.
When the first-class horizontal route passes through large rock fault zones or areas with unstable geological structures, the selection should be jointly studied and selected in conjunction with the relevant geological and seismic departments. Certainly.
5.1.2 Select a leveling point
When selecting a leveling point, it must be able to ensure that the foundation of the point is solid, stable, safe and quiet, and that it is conducive to the long-term preservation and observation of the landmark. The leveling points should be chosen as close to the route as possible in institutions, schools, and parks. Burial level points should not be selected in the following locations: locations prone to flooding, moisture or with high groundwater levels; a.
b.
c.
d.||tt ||e.
Areas prone to landslides, landslides, subsidence, uplift and other local ground deformations; mounds, river embankments, alluvium banks, and soft soil with large changes in groundwater levels (such as near oil wells and machine wells) ); within 50m from the railway, 30m from the highway (special circumstances may be considered as appropriate) or other locations subject to severe vibration; on buildings that are not strong or are to be demolished; f.
will be damaged due to construction in the short term Locations that may destroy landmarks or obstruct observation; g.
Locations where the terrain is hidden and difficult to observe.
5.1.3 Selection of bedrock level points and basic level points Bedrock level points and basic level points should be selected as far as possible on bedrock outcrops or not deep from the ground. Geologists should participate in the selection of bedrock benchmark points, and geological drilling should be carried out if necessary. When selecting the location of the basic level point in the soil, special attention should be paid to the depth of the groundwater level, whether there are holes and quicksand in the ground, whether the soil is solid and stable, etc., to ensure that the marking stone is stable. 5.1.4 What should be done after the point is selected
GB 1289791
After each level point is selected, a point mark with a point number and type of marking stone should be set up and pressed The format of A2 in Appendix A is to fill in the mark of the leveling points. In the process of selecting a leveling route, a leveling route map must be drawn in accordance with the provisions of A1 in Appendix A. For the nodes of the leveling network, the node connection test diagram must be filled out in the format of A3 in Appendix A. 5.1.5 The collected data should be supplemented when selecting sites
If there are still some required data that cannot be collected during technical design, then when selecting sites, it is also necessary to understand the physical geography and transportation of the survey area Transportation, material supply, sand and gravel, water sources, migrant workers, etc., and collect other relevant information. 5.1.6 Data that should be handed in after point selection
: record of leveling points, leveling road map, node connection survey map, b. Necessary geological exploration data;
c, point selection Relevant data collected from Proposed marker stone type, quantity statistics table, etc.). 5.2 Buried stones
5.2.1 Types of standard stones
Level standards include bedrock standard stones, basic standard stones and ordinary standard stones. According to the different materials and specifications of the buried stones, there are eleven types of landmark stones listed in Table 3. Table 3
Serial number
1
2
3
Types of leveling stones
Bedrock leveling stones||tt| |Basic leveling stones
Ordinary leveling stones
Classification of various types of leveling stones
Deep bedrock leveling stones
Shallow bedrock leveling stones| |tt||Concrete basic level standard stone
Steel pipe basic level standard stone
Rock formation basic water mark stone
Concrete ordinary level standard stone
Steel pipe ordinary level standard stone| |tt||Ordinary level mark stone for rock formation
Ordinary level mark stone for concrete column
Dry-breaking concrete column level mark stone
Wall foot level mark
Standard stone The burial specifications and material usage are shown in A5 and A6 in Appendix A (Supplement). 5.2.2 Selection of Buried Stone Types | In addition to the design, other marking stones should be determined according to the depth of frozen soil and soil conditions:
a.
stone);
In areas where the soil is not frozen or the depth of frozen soil is less than 0.8m, Bury concrete marking stones (including basic level marking stones or ordinary level marking stones). b. In areas where the depth of frozen soil is greater than 0.8m, the type should be selected according to the regulations on buried stones in frozen soil areas in A5 of Appendix A; c. In areas with hard rock formations Rock formation leveling stones (including basic leveling stones or ordinary leveling stones) can be buried on outcrops or at locations no deeper than 1.5m below the ground;
d. Where there are solid buildings (houses, monuments, towers) , bridge foundations, etc.) and solid stone cliffs, wall footing level marks can be buried. 5.2.3 Placement of level marks
A metal level mark with a spherical part made of copper or stainless steel should be embedded in the center of the top surface of the leveling stone. The sign must be placed upright and firmly connected. The top of the sign should be 1 to 2cm higher than the surface of the sign. See A4 in Appendix A. 5.2.4 Requirements for burying the sign
5.2.4.1 Bedrock. Burying of leveling stones
GB12897-91
a. Leveling stones in deep bedrock (the buried rock layer is more than 3m deep from the ground) should be designed with single or multi-layer protection according to geological conditions. Tubular marking stones must be designed and constructed by professional units; b. For shallow bedrock (the depth of the buried rock layer is no more than 3m from the ground) level marking stones, the covering and weathered layer outside the rock layer should be completely removed, and then placed on the ground. Dig a 1.0m deep pit into the rock formation, tie steel bars in it and then pour concrete pillars. The height of the pillars and the size of the cross-section depend on the depth of the bedrock from the ground, whichever can ensure the stability of the standard body and facilitate observation. . Place a foot level mark 0.7m below the upper mark on the north side of the pillar. When the height of the right side of the pillar is less than 0.7m, an ordinary level mark can be placed on the bedrock below the north side. See A5 in Appendix A for the burial specifications.
5.2.4.2 Construction and burial of concrete level marking stones
The basic concrete marking stones must be poured on site. For ordinary concrete marking stones, the columns can be prefabricated first and then transported to various points for burial. In areas where conditions permit, both basic marking stones and ordinary marking stones can be chiseled out of a solid block of granite and other hard stones to replace the concrete pillars with pillars of no less than the specified size, and a smooth hemisphere can be chiseled in the center of the top to replace the level mark. . When the pillars are buried, their chassis must be poured on site. 5.2.4.3 Construction and burial of rock stratum standard stones
When burying basic mark stones or ordinary mark stones on exposed rock strata, the weathered matter on the surface must first be removed, and a pit with a depth of 0.5m and a diameter of 0.7m must be dug. Drill holes for placement of level signs and embed signs. It is prohibited to bury leveling points on isolated rocks above the ground. When the depth of the rock layer is greater than 1.0m, a plane slightly larger than the bottom surface of the pillar can be carved out of the rock layer, and a pillar stone of a basic marking stone or an ordinary marking stone can be burned and poured above it. The rock formation level mark must be buried 0.5m below the ground. For the burial specifications, see A5 in Appendix A (Supplement). 5.2.4.4 Burying of Marking Stones in Deep Frozen Soil Areas and Permafrost Areas For ordinary horizontal marking stones buried in deep frozen soil areas, trace blasting technology can be used to expand the bottom of the pit. Make it into a spherical or other relatively regular shape, and pour the marking stones on site.
For marking stones buried in permafrost areas, the base must be buried below the maximum thaw line. Mechanical or manual drilling is used, and the marking stones are poured on site. See A5 in Appendix A for burial specifications.
5.2.5 External decoration of the standard stone
After the horizontal standard stone is buried, its external decoration must be carried out according to the following requirements: a. After the deep bedrock marking stones are buried, a certain size of solid house must be built outside them; b. After the shallow bedrock marking stones are buried, masonry expansion walls should be built around the point, and their specifications should be no less than 1.5m×1.5 m×1.0m, build a masonry square or round well with an inner diameter of 0.5m×0.5m×0.5m around the sign, an indicator plate is set above, and an indicator monument is set outside the retaining wall on the side facing the road;
Basic After the leveling stones and ordinary leveling stones are buried, protective ditches are generally dug according to the specifications of Figure A11 in Appendix A (Supplement), c.
Buried indicator monument:
d, buried in institutions and schools , for basic and ordinary level marking stones in residential courtyards and buried in cultivated land and water network areas, no protective trenches shall be excavated and no signposts shall be set up. However, a protection well must be built according to the specifications of Figure A12 in Appendix A (Supplement) and an indicator plate must be covered; e. In open areas such as grasslands, deserts, and Gobis, in addition to digging protective ditches and setting up indicator monuments in accordance with regulations, nearby Set up 2 to 3 azimuth piles, and you can also build small beautiful signs,
f.When burying mark stones in mountainous and forest areas, azimuth piles can be set up on the roadside closest to the level point; various azimuth piles, battle marks and other objects can be made of wood, stone, concrete or metal materials according to site conditions, and are made of red Write the point number and point direction in an eye-catching position by using paint or imprinting, and indicate the direction and distance of the azimuth object in the point mark; h. If it is inconvenient to excavate the horizontal mark for the lower mark due to the construction of a protective wall (well), the height difference between the upper and lower marks must be measured twice using a horizontal rod and a special steel ruler before building the protective wall. The difference between the two times should not exceed 1mm. , fill in the height difference in the dot mark. 5.2.6 Regulations for changing the location of buried stone points
Level mark stones are generally buried according to the selected type of mark stone and the location of the buried stone. If during the process of burying stones, it is found that the original selected point does not meet the requirements of Article 5.1.2, the point can be re-selected and marked, and the route map can be corrected. 5.2.7 Occupation and custody of leveling stones
GB12897--91
After the leveling points are selected, the land occupied by the buried stones shall obtain the consent of the land users and managers, and Handle land acquisition procedures in accordance with the Land Management Law.
During the process of burying stones, the significance and precautions of protecting measurement marks should be publicized to local people and cadres. After the stone burying is completed, the entrustment and custody procedures should be completed with the local government agencies. The format of the entrustment letter is shown in Appendix A. A8 in 5.2.8 The stability time limit of the standard stone
After the horizontal standard stone is buried, it needs to go through at least one rainy season in general areas, and at least one freezing and thawing period in the permafrost area. The standard stone set on the rock layer At least one month must pass before observations can be made. 5.2.9 Documents that should be handed over after the stone burial
Entrustment letter for custody of survey marks and documents approving land acquisition: a
Notes on level points and route map after stone burial; b.|| tt|| Technical summary of the stone burying work (no description of the stone burying work, special problems in the stone burying and suggestions for observation work, etc.). c.
Technical requirements for instruments
6
6.1 Selection of instruments
The instruments used in leveling measurements shall be in accordance with the provisions of Table 4. Table 4
Serial number
2
3
4
Instrument name
Automatic leveling instrument
or bubble level
Two rows of divided lines
Invar alloy ruler
Theodolite
Photoelectric distance finder
6.2 Calibration of the instrument||tt| |Minimum model
etc
DSZ05
DS05
DJ
Class I
Third class
DSZ1||tt || DS1 | | tt | | DJ1 | |For cross-river leveling, its basic parameters can be found in GB3161. For cross-river leveling piles, its accuracy classification can be found in ZBA76002 "Medium and Short-range Photoelectric Distance Measurement Specifications"
6.2.1 Inspection of photoelectric distance meters Implemented in accordance with ZBA76002 regulations. The ruler length ratio device (or third-class standard metal linear ruler) used for field instrument inspection should be sent to the relevant calibration unit for inspection every two years. 6.2.2 For newly shipped instruments and instruments used for pre-operation and cross-river leveling measurements, the inspection shall be carried out in accordance with the provisions of Table 5. Table 5
Serial number
1
2
3
4
Instrument
Level rod
Inspection items
Inspection of the ruler C, see B1 in Appendix B (Supplement)) Calibration of the circular level on the ruler (See B2 in Appendix B (Supplement)) The curvature of the dividing surface of the ruler is poor Determination (see B3 in Appendix B (Supplement)) Determination of the nominal meter length of the scale and accidental errors in divisions Determination of the tension of the scale tape
Determination of the temperature expansion coefficient of the scale
New instrument| |tt||+
+
+
+
Before homework
★
+
+|| tt||+
x
river water
estimated amount
+
x
+
+||tt ||+
Serial number
7
8
9
10
11
12
13
14
15
17
18
19
20
21
22| |tt||23
24
25
Instrument
Ice Wild Goose Ruler
Level
Theodolite
GB12897— 91
Continued Table 5
Inspection items
Determination of the zero-point difference of a pair of level scales and the difference of Kiev graduation readings (see B4 in Appendix B (Supplement))| |tt|| Determination of the perpendicularity between the central axis of the scale and the bottom surface of the scale [See B5 in Appendix B (Supplement). For inspection of the level only, see B7 in Appendix B (Supplement)} General calibration of the level on the level instrument [See B8 in Appendix B (Supplement)} Determination of optical micrometer gap motion difference and reticle value (see B9 in Appendix B (Supplement)) Determination of errors in line-of-sight observation (see Appendix B (Supplement) Determination of the compensation error of the BI0T automatic leveling instrument [See B11 in Appendix B (Supplement)) Calibration of the crosshair [See B12 in Appendix B (Supplement)] Determination of sight distance constant L See Appendix B (Supplement) Determination of operating error of B13 focusing lens in ) [See calibration of B14 bubble level cross error in Appendix B (Supplement) [See B15 in Appendix B (Supplement)] i-angle calibration [See Appendix B B16 in (Supplement)) Determination of the swing angle 2c of the double-position automatic leveling instrument [See B17J
in Appendix B (Supplement) Determination of error and vertical axis error in height difference observation of measuring stations ( See B18J in Appendix B (Supplement) | |tt|| Determination of the reticle value of the leveling instrument [See B20 in Appendix B (Supplement)] Determination of the line difference of the vertical dial micrometer [See B21 in Appendix B (Supplement)] - Measurement of vertical Determination of errors in angular observations (see B22 in Appendix B (Supplement)) New instrument
+
+
+
+
+
+bZxz.net
+
+
+
+
+
+
Before homework| |tt||+
+
+
+
+
+
+
Crossing the River Water|| tt||Accurate day measurement
+
+
+
x
+
+
+|| tt||+
十
Ten in Table 5 indicates the items that should be inspected. When the instruments and methods used are irrelevant to the inspection, inspection is not required. Inspection items 4, 5, 6 and 21 in the table should be sent to the relevant verification unit for inspection. For the two inspections 4 and 5 in the table, if the ruler is not used for leveling operations within one year after the inspection, and it is tested by a field length comparator before the next operation, and the length change does not exceed 50m, these two inspections can be dispensed with, and the previous inspection will be used. One measurement result. Otherwise, inspection is still required.
6.2.3 The relevant items affected by the repaired and calibrated instrument should be inspected, among which item 21 must be inspected. 6.2.4 Within one week after the start of the operation, the i angle should be checked every day (item 18 in Table 5), and the automatic leveling level should be checked once a day, and the bubble level should be checked twice a day (once in the morning and once in the afternoon). If: When the angle is relatively stable, check the calibration every 15 days in the future. 6.2.5 Items 2 and 10 in Table 5 should be checked before starting daily work. If there is any doubt about the quality of a certain part of the instrument, the corresponding inspection should be carried out at any time.
6.2.6 When the average height difference between the level points in the measurement area exceeds 150m, a field length comparator should be used to detect the nominal meter length of a pair of scales once a month (see Appendix B (Supplement) B6]. When the operation period exceeds three months, this item and the inspection of item 3 in Table 5 should also be added
GB12897-91
The inspection in Table 5 should be carried out after the operation period. 3, 4, and 5 once each. 6.2.7
6.3Instrument technical indicators
Instrument technical indicators shall be implemented as specified in Table 6.
Table 6
Serial number
1
2
3
4
5
6| |tt||7
8
9
10
11
12
13
14||tt ||15
16
17
18
19
20
21
22
23
Instrument technical index items
Scale bending difference
Zero point difference of a pair of scales
Kiev division constant deviation of the scale
Verticality of the base of the scale Error
Deviation of the nominal meter length of a pair of rulers
Deviation of the nominal meter length of a pair of rulers
The change in the nominal meter length of a pair of rulers before and after the test The field test results of the nominal meter length of a pair of rulers are the same as before Deviation of primary indoor measurement result
accidental error of scale division
deviation between scale belt tension and nominal value
inclined spiral gap dynamic difference
micrometer division Value deviation
Micrometer reticle value gap motion difference
Automatic leveling level compensation error
Error in line of sight observation
Focusing lens operation error
Angle
2c angle
Error in height difference observation of measuring station
Vertical axis error
Magnetic error of automatic leveling instrument
Vertical dial micrometer Line error
Error in vertical angle observation in one measurement round
Indicator tolerance
Equal
4.0mm
Second level
4.0mm
0.10 mm
0.10mm
0.05mm
j0.05mm
0.10mm
100μm
50 μm| |tt||30μm
50μm
13μm
1.0kg
2.0%
1.0 μm
2.0 grid
0.10m
0.40%
0.50mm
15.0m
40.0
0.08mm
0.05mm
0.02| |tt||1.00
1.50*
0.10mm
100m
50 μm
30 μm
50 pam||tt| |13 μm
1.0 kg
2.0*
1.0μm
2.0 grid
0.20
0.55\
0.50 mm
15.0~
40.0″
0.15mm
0.10 mm
0.04
1.00\
1.50|| tt||Over-limit handling method
Apply correction to the ruler
Adjust
Use the actual measured value
Use the ruler circle
It is prohibited to send it to the factory for correction|| tt||Adjust
Analyze the reasons and handle the measured results correctly according to the situation
Send to the relevant unit for re-measurement
Prohibited use
Only screw-in use||tt| |Prohibited use, send to the factory for repair
Prohibited use
Calibration (automatic leveling should be sent to the factory for calibration). If the measurement result exceeds 20, it will be invalid
Prohibited use and sent to the factory for calibration
Prohibited use
The magnetic error of the automatic leveling instrument in Table 6 refers to the maximum deviation of the line of sight caused by the automatic leveling instrument under the action of a steady magnetic field in the horizontal direction with a magnetic induction intensity of 0.05mT. 7 Level Observation
7.1 Observation Method
7. 1. 1
《The first and second level water thrust measurements adopt a single route round trip observation. The round-trip survey of a route must be carried out along the same road using the same type of instrument and turning point ruler. | |tt | Measurement). If the section is long, the section can also be divided into several sections of 20 to 30 km, and round-trip observations of all measurement sections can be carried out continuously within the sections. 7.1.3 The forward measurement (or return measurement) and the return measurement (or forward measurement) of the same measurement section should be conducted in the morning and afternoon respectively. On cloudy days when the daytime temperature changes little and when observation conditions are good, round-trip measurements of several miles can be carried out in the morning or afternoon. However, the total number of stations for this kind of mileage should not exceed 20% of the total number of stations in the section in the first class, and should not exceed 30% of the total number of stations in the section in the second class. 7.2 Observation time and meteorological conditions
Level observation should be carried out when the image of the scale reticle is clear and stable. Observations should not be made under the following circumstances: a.
b.
c.
d.
e.
after sunrise and before sunset Within 30 minutes;
Within about 2 hours before and after the sun is at the zenith (the noon interval can be appropriately increased or decreased according to the region, season and weather conditions); when the image of the scale reticle jumps and is difficult to follow: when the temperature changes suddenly ;
When the wind is too strong and the ruler and instrument cannot be stable. 7.3 Setting up measuring stations
7.3.1
For first- and second-class level observations, ruler piles or ruler platforms must be selected according to the soil quality of the route (the weight of the ruler platform shall not be less than 5kg) as the turning point ruler support. The number of foot piles or foot platforms should be no less than 4. Large cap nails can be used in special areas. 7.3.2
The sight length of the measuring station (distance from the instrument to the ruler), front-to-back sight distance difference, and sight height shall be as specified in Table 7. Table 7
Level
First class
Second class
Instrument type
DSZ05,DS05
DS1.DS05
Note: The lower wire is the sight wire near the ground.
7.4 Measurement sequence and method of measuring stations
Sight length
30
50
When measuring in the direction of the measurement, odd-numbered measuring stations should be aligned with the ruler markings The order is: 7.4.1
a.
b.
c.
d.
7.4.2
a.| |tt||b.
c
d.
7.4.3
7.4.4
a.
Rear view ruler The basic division of
The basic division of the front-sight ruler;
The auxiliary division of the front-sight ruler;
The auxiliary division of the rear-sight ruler.
When measuring forward, the order of scale divisions at even-numbered measuring stations is: the basic divisions of the front-sight scale;
the basic divisions of the back-sight scale;
the back-sight scale The auxiliary division of
The auxiliary division of the front-sight ruler.
Difference in sight distance before and after
0.5
1.0
Accumulation of sight distance difference between front and rear at any measuring station
1.5||tt ||3.0
When measuring back, the order of sighting the ruler at the odd and even measuring stations is the same as that at the even and odd measuring stations respectively. Optical micrometry is used for station observation. The operating procedures of the station are as follows (in the past, odd-numbered station measurements were taken as an example): line of sight height
(lower wire reading)
0.5
>0.3
m
First level the instrument (when the bubble level telescope rotates around the vertical axis, the separation of the images at both ends of the leveling bubble shall not exceed 1cm. The round bubble of the automatic leveling level is located in the center of the indicator ring) :b. Align the telescope with the rear sight scale (at this time, use the circular level on the scale to adjust the scale vertically) so that the images at both ends of the level are nearly consistent (the double-position automatic leveling level should be placed in the first position). Then use the upper and lower wires to sight the basic divisions of the ruler for sight distance readings. The fourth digit of the sight distance is read directly from the micrometer drum. Then, make the bubbles of the matching level accurately match, rotate the micrometer drum and use the wedge-shaped bisecting wire to accurately align the basic division of the scale, and read the basic division of the fixed scale and the reading of the micrometer drum (read to the smallest division of the micrometer drum);3
m
First, level the instrument (when the bubble level telescope rotates around the vertical axis, the separation of the images at both ends of the level bubble shall not exceed 1cm, and the circular bubble of the automatic level is located in the center of the index ring): b. Aim the telescope at the rear sight scale (at this time, use the circular level on the scale to adjust the scale vertically), so that the images at both ends of the level are almost aligned (the double-position automatic level should be placed in the first position). Then use the upper and lower wires to aim at the basic scale divisions of the scale to read the sight distance. The fourth digit of the sight distance is directly read from the micrometer drum. Then, make the bubble of the level accurately match, rotate the micrometer drum and use the wedge-shaped bisector wire to accurately aim at the basic scale divisions of the scale, and read the basic scale divisions and the micrometer drum readings (read to the smallest scale of the micrometer drum);
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