Some standard content:
GB16789-1997 | | tt | certain technical conditions and levels. This standard provides a basis for establishing high-precision field length measurement and verification standards. Appendix A to Appendix B of this standard are standard appendices; Appendix C to Appendix L are all reminder appendices. This standard is proposed and administered by the State Bureau of Surveying and Mapping. This standard is drafted by the Surveying and Mapping Standardization Institute of the State Bureau of Surveying and Mapping. The main drafters of this standard are: Peng Yuhui and Duan Xueqing. 1 Scope
National Standard of the People's Republic of China
Specifications of the baseline measurements
Specifications of the baseline measurementsGB16789--1997
This standard specifies the accuracy, Design requirements, measurements, calculation of results, selection of baseline field, specifications and embedding methods of ground marking stones and observation piers, etc.; suitable for establishing a proportional long baseline. 2 Referenced standards
The provisions contained in the following standards constitute provisions of this standard by being quoted in this standard. At the time of publication, the editions indicated were valid. All standards are subject to revision and parties using this standard should explore the possibility of using the latest version of the following standards. JJG306-82 Calibration Regulations for Measuring Instruments Accuracy and design of 24-meter Invar base ruler 3-ratio long baseline
3.1 The first-ratio long baseline is a high-precision field length measurement verification standard, and its relative accuracy should be equal to or higher than 1 ×10-°. 3.2 The length of the longer baseline must be more than 600m, preferably 1000m to 2000m. 3.3 For segmented design of longer baselines, it should be noted that the total combined side lengths of the baseline segments cannot be repeated. The method is as follows: segment according to integer multiples of the 24m invar line ruler, see Appendix L (Appendix for prompts). 4. Selection of long baseline field
a) The site of the baseline field should have convenient transportation, stable geological structure, no faults, and can be used for a long time. b) The baseline site should avoid interference and reflectors, such as high-voltage lines, microwave transmission towers, radio transmission towers, radar stations and other areas with strong electromagnetic wave radiation devices.
c) Choose an equal-sloping section with flat terrain, good vegetation, and a total slope of less than 1°. d) There are no lakes, ponds, sand ditches, etc. near both sides of the baseline. The distance from the metal mesh fence should not be less than 3m, and the distance from the building should not be less than 2m. There are no trunk roads crossing the survey line.
e) Try to avoid tall buildings in the direction where the baseline extends. 5 Specifications and burial methods of ground marking stones and observation piers 5.1 For the specifications and styles of ground marking stones and observation piers with longer baselines, see Appendix A (Standard Appendix) and Appendix B (Standard Appendix). 5.2 Marking stones and observation piers should be marked with the date of burial, point number and unit name, and their alignment marks should be clear and durable. The cylindrical marking stones or observation piers at the endpoints of the baseline and each segmentation point should be equipped with precision centering devices or forced centering devices, as well as protective devices. 5.3 The marking stones should be poured on-site with reinforced concrete in the forming pit and maintained for 48 hours after pouring. The depth of the forming pit marked on the right is 3m in general areas; it must be buried below the frozen soil line in frozen soil areas. The surface of the marking stone is 0.2m below the ground. The depth of the observation pier forming pit is generally 5m. The frozen soil zone must be below the frozen soil line. The pier surface is 1.2m above the ground. 5.4 When burying and setting out, the distance should be accurate to centimeters, and the orientation deviation should not be greater than 5\. 5.5 After the observation pier or marking stone is buried, length measurement can only be carried out after one year. Approved by the State Bureau of Technical Supervision on 1997-05-26 and implemented on 1998-03-01
6 Calibration of measuring instruments
6.1 Verification of precision Invar line ruler
GB16789--1997
Invar line ruler should be sent to the national metrology and verification department for length verification every year. The expansion coefficient is verified every five years. The provisions of JJG306 shall be followed during calibration.
6.1.1 Requirements for Invar wire ruler and additional weight a) When the temperature changes by 1°C, the expansion of Invar wire ruler per meter length shall not be greater than 0.5um; the actual length of Invar wire ruler and the standard The difference in weighing length shall not be greater than 5mm. The temperature correction number is calculated according to the formula (1): t = 0.2(t- 20) + 0.068(t2 20), μmb). The difference between the weight of each weight and 10kg shall not exceed 0.005kg. 6.1.2 Field comparison of Invar line ruler
..(1)
When doubts arise about the length of Invar line ruler during operation or after long-distance transportation, the comparison should be made in the field. Comparison of corrugated line rulers to examine changes in ruler length.
Due to the field comparison of the tile ruler, two axle rod frames should be firmly arranged in a flat place with a distance of 24m±(1~3)cm. The turf should be shoveled away from the toes of the axle rod frames. . The two shaft heads should be as high as possible. 30 minutes before comparison, remove the Invar line ruler from the drum and tension it (without weighting the hammer). A total of 12 test runs were performed for comparison. Each measurement round includes:
a) Use various Invar linear rulers to measure the distance between the two-axis rod heads in the order of 1, 2, and 3n. The observers at the front and rear ends of each foot will read three measurements at the same time. The number of times, the difference between each distance (before and after) shall not exceed 0.2mm. b) The observer, together with the ruler frame, pulley, and weight, changes positions (the baseline ruler does not turn around), and then connects each ruler to n3, 2, and 1 in order to measure the distance between the two shaft rod heads. The regulations are the same as paragraph a).
The air temperature must be measured at the beginning, end and middle of each measurement round. Take the median of the 12 measurement results for each ruler, and add the ruler length correction and temperature correction. Calculate the median of the corrected results for each ruler (results that differ by more than 0.2mm will not be included). The difference between the results of each ruler and the median should be within 0.05mm. For the field comparison calculation of the var line ruler, see Appendix C (Appendix of Tips). 6.2 Verification of the Yinwa complementary ruler
The length of the Yinwa complementary ruler should be measured every six months. The measurement was carried out in the field using two 24m Invar wire rulers. Choose a flat place and securely arrange the two shaft racks 24m apart. The shaft heads should be as high as possible. 30 minutes before the measurement, take out the supplementary ruler and the 24m invar line ruler from the box and tension them (without weighting the hammer). The measurement procedure is as follows: a) Use two 24m Invar rulers to measure the distance between the two shaft rod heads back and forth. During the return measurement, the two observers, together with the ruler frame, pulley and weight, change positions. Read three times at the front and rear ends of each foot. The difference between the distances (before and after) shall not exceed 0.2mmb). Place an intermediate shaft rod frame between the two shaft rod frames. The distance between each two adjacent shaft rod frames is a supplementary foot. length, each intermediate shaft rod frame should be precisely positioned within the sighting plane of the shaft rod frames at both ends, and the height difference between the tops of two adjacent shaft rod frames should not exceed 5mm. c) Measure the height difference of each shaft head back and forth and use a supplementary ruler to measure the distance back and forth. When measuring back, the supplementary ruler should be turned around and the two observers, together with the ruler frame, pulley and weight, should be replaced. Each foot is read 6 times at the front and back ends, and the difference between the distances (front and back) shall not exceed 0.2mm.
d) Remove all intermediate shaft rod brackets. Then use two 24m Invar wire rulers to measure the distance between the two shaft rod frames. The regulations are the same as paragraph a). The above measurement is one measurement round, and a total of two measurement rounds must be measured. The air temperature should be measured at the beginning and end of each measurement round. Please see Appendix C (Appendix of Tips) for the field comparison calculation of supplementary feet.
6.3 Calibration of levels, leveling rods and theodolite Before setting out in the field, the leveling instrument, leveling rods and theodolite must be inspected. During the operation, the angle of the level should be measured once a day and corrected to within 6\.
6.3.1 The inspection of levels and level rods shall be carried out in accordance with the inspection items and methods of third-class level measurement. GB16789—1997
6.3.2 Theodolite shall generally be inspected according to the needs of baseline measurement and in accordance with the requirements and methods of national triangulation and precision wire measurement. 6.4 Calibration of thermometer
The thermometer should be sent to the local meteorological measurement and verification department for calibration once a year. The nominal accuracy is not greater than 0.2°C. 7. Measurement of longer baselines
7.1 Arrangement of the axis rod holder
7.1.1 If the endpoint of the baseline is a landmark, first configure the axis rod bracket on the endpoint, and the precise position of the axis rod head is determined by two The theodolite is determined by the projection of each other at 90 degrees. Set the theodolite on the first node of the baseline, sight the shaft head on the end point, and then adjust the shaft frame in turn. The difference between the distance between two adjacent shaft rod frames and 24m shall generally not be greater than 3cm. When installing the axis rod holder, two of the legs should be parallel to the direction of the baseline, and the third leg should be installed alternately on the left and right sides of the baseline direction, and insert it firmly into the soil and tighten all the screws. The shaft head should be vertical and the crosshair should be in the same direction as the baseline. The position of the axis rod holder at each segment point in the middle must be determined by the projection of two theodolite. When the axis rod holder is placed at the location of the theodolite, remove the theodolite, use two theodolite to project the last axis rod bracket in the section at 90 degrees, and check the distance of the last span. 7.1.2 The shaft racks of the entire baseline should be numbered uniformly. 7.1.3. On soft or muddy soil, the shaft frame should be placed on wooden piles driven into the ground. The diameter of the wooden pile is 7cm~8cm, and the length of the wooden pile depends on the geology, but it should not be shorter than 0.3m. Tall wooden piles can also be used instead of the shaft frame. 7.1.4 Distances that are less than one base ruler shall be measured using Invar's supplementary ruler. Where the supplementary ruler is used, the terrain should be very flat, and the height difference between two adjacent shaft heads should be as small as possible.
The following principles should be followed when using the supplementary ruler:
a) It should be used as little as possible;
b) The supplementary ruler shall not be used to measure distances shorter than 1m; c) The supplementary ruler shall be used to measure The distance between the ruler section and the section point should be less than a 24m ruler section. 7.1.5 If each segment point of the baseline is an observation pier, set the theodolite on the node, align the endpoint observation pier mark, and adjust the axis rod frame in sequence. 7.2 Level measurement of the shaft head
7.2.1 Level measurement of the shaft head uses an S-level level and a 1.5m long double-sided ruler. 7.2.2 The procedure for leveling the shaft head is the same as the length measurement. If the length measurement is performed as a round-trip measurement in sections, the shaft head level measurement is also divided into sections as a round-trip measurement. If the length measurement is based on the full length, the shaft head level measurement is also based on the full length. Measurement to and from. The forward measurement of the shaft head level measurement is carried out before the forward measurement of the length measurement, and the back measurement is carried out after the back measurement of the length measurement. 7.2.3 When measuring the level of the shaft head, take readings from both sides of the ruler according to the middle wire method. When measuring, the circular bubble on the level rod should be centered. The number of shaft racks read by one measuring station shall not exceed 5. The measuring station should be selected so that the distance from each axis rod frame is approximately equal, but the sight distance should not exceed 75m. 7.2.4 Read the black and red sides of the scale on each axis rod frame. After calculation, the difference shall not exceed 2mm. According to the height difference between the black side and the red side of the ruler, the difference between them shall not be greater than 2mm. The distance between two adjacent shaft heads is calculated to 0.1mm, see Appendix K (Appendix for prompts). 7.2.5 For sections with an inclination greater than 1/24 and short distances less than 24m in length, the height difference should be measured twice. When changing the height of the instrument between two measurements, the difference in viewing distance shall not be greater than 2m. The difference between the two measured heights shall not exceed 2mm. 7.2.6 Between two adjacent shaft rod heads, the height difference between the previous measurement and the back measurement shall not exceed the following values: 3mm for the height difference less than 1m
3mm for the height difference greater than 1m 2mm#
The length of the supplementary ruler is 1mm.
If the height difference exceeds the limit, the corresponding shaft frame should be re-measured. If it is confirmed that the shaft rod frame was bumped and exceeded the limit after the outgoing test and before the return test, it will be necessary to return to the test and retest. The inclination correction can be performed separately for round-trip measurements. For the inclination correction calculation, please refer to Appendix H (Appendix for prompts). 7.3 Length measurement
7.3.1 The first-class baseline is measured using six Invar linear rulers. Under normal circumstances, a first-class baseline should be divided into three sections with approximately equal distances for measurement. Each section is measured with four Invar wire rulers (two of which are used for forward measurement and the other two for backward measurement). The configuration of the Invar line ruler used for each section measurement is shown in Table 1.
Table 1 Invar line ruler configuration used for measurement in each section Section number
Scale number
First section
Second section
Third section Section
round trip
outbound
1,2
5.6(3,4)
3,4(5,6)||tt ||The two Invar wire rulers used each time should preferably have different expansion coefficients. When the length of the baseline is short, there is no need to divide it into sections. Three Invar wire rulers are used for forward measurement and return measurement respectively. 7.3.2 Length measurement implementation steps
Return measurement
3,4
1,2(5,6)
5.6(1,2)||tt| |a) 30 minutes before measurement, the Invar line ruler should be placed in a cool place in the open air to make it consistent with the outside temperature. b) When measuring, the zero reticle of the three-sided reticle at both ends of the linear ruler should be behind the direction of measurement forward. c) Before hanging the ruler, the front-end reader should check whether the front-end shaft frame (or wooden stake) is firm, whether the shaft head is set correctly, and whether all screws are tightened.
d) Adjust the three-edge dividing ruler so that its bevel edge slightly touches the shaft head and is consistent with the cross lines on it. e) The heavy hammer must not touch the ground. Readings can only be started after the scale and weight stop swinging. f) For each foot section, read three logarithms at the front and rear ends of each Invar line ruler to 0.1mm. The reticle should be moved 1cm to 2cm between two adjacent pairs of readings. The direction of movement is from small to large for forward measurement and from large to small for backward measurement. g) When measuring, the commands to lower the hammer, lift the hammer, and start reading are all issued from the front end, and the actions must be performed at both ends at the moment when the rear end should be "ok".
h) The number reporting starts from the front-end reader, followed by the back-end, reporting the number below millimeters first, and then centimeters and millimeters. After reading the three logarithms, the reader should raise the triangular ruler by 1cm to 2cm and wait for the bookkeeper's command. i) The bookkeeper records the readings in turn and finds the "front-to-back". The difference between the "front-to-back" of each ruler must not exceed 0.2mm. If it exceeds the limit, a supplementary reading should be made. If five consecutive pairs of readings are inconsistent, the measurement should be repeated. See Appendix J (Appendix of Prompts) for the record format. i) At each foot section, attention should be paid to the difference in the dimensions measured by the two Invar line rulers. This difference should be compared with the difference between the two Invar line rulers, and the difference between them should not exceed 0.2mm. If the limit is exceeded, analyze and eliminate the possible reasons for the limit violation, and retest. If the difference between the remeasurement result and the original measurement result of the same ruler and the difference between the median and the result of another ruler do not exceed 0.2mm, the median of the remeasurement result and the original measurement result of the same ruler shall be used. Otherwise, only the retest results are used.
If the remeasurement results are different as before, it may be that the length of the Invar line ruler has changed. In this case, a field comparison of the Invar line ruler should be made to understand the changes in the ruler length. , and use the backup Invar line ruler to replace the Invar line ruler whose length has changed for measurement. If the corrugated line ruler is damaged, dropped or the length of the ruler is changed, it should be recorded in detail in the handbook. k) When moving to the next foot section, the rear-end reader (together with the ruler frame, pulley, and weight) moves forward and becomes the front end of the lower ruler section; the original front-end reader (together with the ruler frame, pulley, and weight) remains at the original position. The ground becomes the rear end, and pay attention to protect the position of the shaft rod bracket from changing. Holding the ruler stand, the person lifting the weight along with the instrument can also maintain the position of the front and rear ends, advance each foot segment sequentially, and then switch positions at the front and rear ends at one-half of the segment. 1) After the outgoing test is completed, the back test will be carried out. During the return test, the two readers and instruments exchanged positions and replaced the Invar line ruler. m) Read the temperature twice every five feet. The weather and time should be noted at the beginning and end of each segment. n) When measuring with an Invar ruler, six logarithms should be read for both forward and return measurements. When measuring a length shorter than one complementary ruler, use one end of the complementary ruler to measure forward and the other end to measure back.
0) In order to check the short distance with a complementary ruler, a steel tape measure must be used (the short distance measured with a complete complementary ruler does not need to be tested). The configuration and number of the shaft rod bracket using supplementary feet should be shown on drawings. P) The bookkeeper should always check the number of the shaft rack with the actual number. 7.3.3 The mutual difference between the segment lengths calculated based on each Invar line ruler should conform to the following formula: In the formula: 4 The mutual difference in segment length, mm;
t——segment length, km.
GB16789-1997
≤3
When the limit is exceeded, the section should be retested in one direction with two Invar line rulers. 7.3.4 Baseline measurement is prohibited under the following circumstances: a) When the horizontal wind speed is greater than 4m/s, or when the longitudinal wind speed is too large to facilitate operation; b) When it rains;
c) The air temperature exceeds the Invar line ruler The temperature range specified in the calibration certificate. 8 Measurement data processing
8.1 List the Invar line ruler table used for baseline measurement, see Appendix D (Appendix for prompts). 8.2 Calculate the length of each section based on each Invar line ruler. -(2)
After adding the temperature correction number, ruler length correction number, tilt correction number and reticle correction number to the sum of the readings of each Invar line ruler in each section, it is calculated for each Invar line ruler segment length. See Appendix E (Appendix of Tips) for segment length calculation. Among them, the reading of the Yinwa line ruler is copied from the handbook, the expansion coefficient and ruler length correction of the Yinwa line ruler are given by the Invar line ruler calibration certificate; the correction number of the reticle ruler is calculated according to formula (3): ||tt| |A(h - a) = 0. 215 5Z(b - a), mm In the formula: (b—a)—
Because the reading difference between the front and rear ends of the tile ruler is m; (3 ) | 8.3 Calculation of the final length of each section
The final length of the section is obtained by taking the average of the section lengths calculated from each Invar line ruler, and adding corrections for catenary asymmetry and gravity changes. The final length calculation of each paragraph is shown in Appendix F (Appendix of Tips). a) Catenary asymmetry correction number △P:
AP=2.993×10-3Zh2,mm | b) Gravity change correction number △g:
Ag = 7.02 × n((g2 — g)/g1), mm where: n-span number
gi
- The acceleration of gravity at the verification point of the line ruler; the acceleration of gravity at the location of a baseline field
g2
g;=9.80615(1-0.002642cos2d)
g2=9.80615(1-0.002642 cos24)
Ag=g2—g1 = 0.025 908 (cos2d, —cos242) Among them: - the latitude of the verification point of the Yinwa line ruler; - the latitude of the location of the baseline field:
, both are acceptable Measure from the map to the nearest 0.1°. 8.4 Calculation of the total length of the baseline
The lengths of each segment are added up, which is the final length of the total length of the baseline. 8.5 Accuracy estimation
8.5.1 Error E of the baseline measurement itself:
E, =± //n(n-1)
(4)
( 5)
*.(6)
7)
(8)
(9)
GB16789—1997
baseline each The round-trip measurement of a section (or section) uses four invar line rulers to obtain four length results. In the formula: the difference between the median of the four lengths and each length, one due to the number of square feet, is equal to 4.
The E of the total length of the baseline is equal to the E, square and square root of each section. 8.5.2 Error E2 of shaft head water thrust measurement: This error of each section, section and full length of the baseline is calculated according to formula (10): E, = ±0.0137/h
where: ZAh——Tilt correction number, mm. 8.5.3 The measurement error of the temperature coefficient of the tile ruler Eg: The measurement error of the temperature coefficient of the 24m tile ruler is ±0.7um/C. The error of each segment, section and the entire length of the baseline is calculated according to equation (11): E,-±0.7(tm-ta)n+μm
where: tm—the average temperature during baseline measurement ; ta - the average temperature when measuring the temperature expansion of the Invar line ruler; the number of segments in one foot,
8.5.4 is used to check the error of the standard rod length of the Invar line ruler and length E4: E. =± 6.4n,μm
Where: n—
The number of segments, sections and 24m full-length segments of the baseline. 8.5.5 The calibration error of the Yinwa wire ruler and the influence of the change in the length of the Yinwa wire ruler Es: E,-±Vdd/4w·n
Where: d——The result of the two calibration results of the Yinwa wire ruler Difference; te
- the number of invar linear feet used to measure the line;
the number of segments in one foot.
Under normal circumstances, the baseline is only verified once a year, so E5 is not calculated. 8.5.6 The total error (uncertainty) E of the final length of the baseline is calculated according to the following formula (for calculation, see Appendix G (Appendix of Tips) )): E=±VE++E++E
9 Provisions for data compilation, results submission and retesting 9.1 Data compilation
9.1.1 Data compilation should include:
a) Measurement unit, operation time and personnel list; b) Sketch of longer baseline:
c) Operation technical requirements;
d) Observation handbook;
e) Calculation Data:
f) Statistical table of observation results and accuracy;
g) Verification data of Invar line rulers and meteorological instruments. 9.1.2 It is recommended to use a computer to print out the content of the data collection. 9.2 Submit the results
a) Acceptance report;
b) A copy of the complete information and results.
9.3 Before the established baseline is put into use, retesting should be conducted for three consecutive years. After activation, retesting will be conducted every three to five years. (10)
.(11)
(12)
-(13)
·(14)
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GB16789—1997
Appendix A
(standard appendix)
Ground marking stone style
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Unit: mmbzxz.net
Description
①Cast iron cover, with 6 ribs inside
②Movable cement pattern, with mesh inside
Thin iron wire
③Fixed cement ring
①Copper screws
Pit solid circle
Unit: mm
Description
①Marking stone requirements It is made of reinforced concrete poured on-site. For steel bars
8mm
② copper screws
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