GB 17501-1998 Specification for marine engineering topographic survey
Some standard content:
GB17501—1998
my country has vast seas and long coastlines, and rich marine resources. With the continuous development of the national economy, people pay more and more attention to the development and utilization of marine resources, and various marine projects have increased significantly. Marine engineering surveys that provide basic maps and data for marine engineering have also developed rapidly.
In order to meet the needs of the development of modern marine engineering surveys and make marine engineering surveys standardized and scientific, it is very necessary to formulate the "Marine Engineering Topographic Survey Specification". This specification is formulated for technical supervision and scientific management of marine engineering topographic surveys. It is a technical standard for marine engineering surveys in the country and various localities. This standard is consistent with relevant national laws and standards. Appendix A, Appendix B, Appendix C and Appendix D of this standard are all appendices to the standard. This standard is proposed by the State Oceanic Administration and is responsible for interpretation. This standard is under the jurisdiction of the Standard Metrology Center of the State Oceanic Administration. The drafting unit of this standard is the First Institute of Oceanography of the State Oceanic Administration. The main drafters of this standard are: Shen Xianzhong, Zhou Xinghua, Zhang Weihong, Zhong Delin, and Xu Sheng. 802
1 Scope
National Standard of the People's Republic of China
Specification for marine engineering topographic surveying
Specification for marine engineering topographic surveying
This specification specifies the basic contents and requirements for marine engineering topographic surveying. This specification is applicable to marine engineering topographic surveying 1:500～1:50000 scale maps. 2 Referenced standards
GB 17501—1998
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised. All parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T5791—19931:50001:10000 Topographic map types 1:5001:10001:2000 Topographic map types GB/T 7929—1995
GB 12317—1990
GB 12898—1991
GB 50026—1993
CH 2001—1992
3 Definitions
Chart types
National third and fourth grade leveling specification
Engineering surveying specification
Global Positioning System (GPS) measurement specification
This standard adopts the following definitions
Marine engineering topographic surveying
f marine engineering topographic surveying Survey of seabed topography and geomorphology required for coastal, offshore and island and reef engineering, and detection of seabed surface obstacles. 4 General Provisions
4.1 Tasks of Marine Engineering Topographic Survey
Survey the seabed topography and geomorphology and detect obstacles in the sea areas (including coastlines, islands and reefs) where marine engineering is implemented, with the aim of providing basic seabed topography maps and micro-topography data for marine engineering design and construction. 4.2 Main Contents of Marine Engineering Topographic Survey Establish the basis for plane and elevation control,
water level observation, determine the relationship between the 1985 national elevation datum, theoretical depth datum and the local average sea level, and calculate the water level correction value during water depth measurement;
seabed topography mapping;
seabed micro-topography mapping;
seabed surface obstacle detection;
coast, island and reef topography mapping.
Approved by the State Administration of Quality and Technical Supervision on October 12, 1998 and implemented on April 1, 1999
4.3 Surveying datum
GB17501-1998
4.3.1 The plane coordinate system adopts the national coordinate system, and other coordinate systems can be used according to the needs of the project; the elevation adopts the "1985 National Elevation Datum". For islands and reefs far away from the mainland, the elevation datum can adopt the local average sea level. 4.3.2 The depth datum of marine engineering measurement adopts the "1985 National Elevation Datum", or other datums can be used as needed. In this case, the relationship between the adopted datum and the theoretical depth datum and the 1985 National Elevation Datum should be given. 4.3.3 The coastline is surveyed and mapped based on the actual boundaries formed by the average spring tide and high tide. 4.4 Measurement accuracy
4.4.1 Mapping scale and plane control measurement accuracy4.4.1.1 When the mapping scale is less than 1/500, the mean error of the weakest point of the plane control network relative to the starting point is less than or equal to ±10cm;4.4.1.2 When the mapping scale is 1/500, the mean error of the weakest point of the plane control network relative to the starting point is less than or equal to ±5cm.4.4.2 The elevation control accuracy of the working leveling point, water gauge zero point and coastal topography measurement of the tide gauge station shall not be lower than the fourth-class leveling measurement accuracy. 4.4.3 In depth measurement, when the surveying scale is 1/500, the positioning error is ±2.0mm on the map; when the scale is less than or equal to 1/1000 and greater than or equal to 1/5000, the positioning error is ±1.0mm on the map; when the scale is less than or equal to 1/10000 and greater than or equal to 1/50000, the positioning error is ±0.5mm on the map; for non-scale offshore positioning measurement, the positioning accuracy should be determined according to the design requirements of the project.
4.4.4 In depth measurement, when the water depth is less than or equal to 20m, the depth measurement error is less than or equal to ±0.2m; when the water depth is greater than 20m, the depth measurement error is ±1% of the measured depth. 4.5 Cartographic accuracy
4.5.1 The error of the length of the gallery is less than or equal to ±0.1mm on the map; the error of the length of the diagonal and square grid lines is less than or equal to ±0.3mm on the map; the rectangular coordinate displacement of the grid intersection is less than or equal to ±0.6mm on the map. 4.5.2 The accuracy of the control point display is checked by the distance between the control points. The number of checked edges for each control point shall not be less than two, and the intersection angle of the checked edges shall be between 30° and 150°, and the error of the edge length is less than or equal to ±0.3mm on the map. 4.6 Projection and framing
4.6.1 The projection adopts the Gauss-Krüger 6° belt or 3° belt projection, and other required projections may also be used; when the mapping scale is less than or equal to 1/2000, the Gauss-Krüger 1.5° belt projection may be used. 4.6.2 The framing adopts the international unified framing or free framing. ：4.7 Diagram symbols
GB12317 is used in sea areas;
GB/T7929 and GB5791 are used in land areas.
4.8 Instrument calibration
All kinds of instruments for marine engineering surveying should be sent to the statutory calibration unit for calibration regularly, and they are only allowed to be used when they are qualified. 5 Technical design
5.1 Basis of technical design
Task orders and contracts issued by relevant departments, technical equipment conditions, and relevant laws and technical standards. 5.2 Project design
Determine the scope of the survey area, the scale of surveying and mapping, and the division of the map, formulate the main technical measures in the surveying work, compile the project design book and draw relevant drawings.
5.3 Professional design
Comprehensively collect and analyze relevant data of the survey area, make preliminary design, conduct field surveys on this basis, modify the preliminary design, and formulate the technical design book.
5.3.1 Data collection and analysis of the survey area
- The latest published land and sea topographic maps; 804
GB 17501-1998
Plane and elevation control results and their descriptions; tidal data;
- Meteorological data,
Other relevant data.
Analyze the reliability and accuracy of the collected data and make a conclusion on whether the data can be used. 5.3.2 Contents of professional design
5.3.2.1 Plane control. According to the known points in the survey area and the scale of the survey, select the method of plane control measurement and the accuracy to be achieved. 5.3.2.2 Elevation control. Determine the survey route and measurement accuracy from the known elevation point to the elevation control point or tide gauge station to be measured. 5.3.2.3 Depth measurement
1) Determine the interval, number and direction of survey lines according to the mapping scale. 2) Determine the location of the shore station (or reference station) according to different positioning methods and means, and estimate the positioning error in the survey area. 3) Determine the location of tide gauges and hydrological points and the water level correction plan. 4) Determine the inspection and measurement methods of the positioning system and depth sounding instruments. 5.3.2.4 Coastal and island topography measurement
1) Divide the map according to the actual situation.
2) Lay out plane and elevation control.
3) Determine the mapping method according to the survey area. 5.3.2.5 Micro-topography measurement and obstacle detection 1) Determine the measurement range.
2) Determine the survey line layout plan according to the requirements of the water depth and coverage rate of the measured sea area. 5.3.3 Field survey
5.3.3.1 Social conditions, natural geography, hydrology and meteorology, transportation, communication, ship use and sheltered anchorage in the survey area. 5.3.3.2 Field conditions of known control points and tide gauge stations in the survey area. 5.3.3.3 Working conditions in the survey area.
5.3.4. Complete professional design based on field survey and submit technical design documents. 5.4 Field implementation plan
The following factors should be considered when determining the field implementation plan: Determine the time for field work;
Selection and division of labor of technical personnel;
-Equipment of major instruments and equipment;
-Ship use plan and ship solution method;
-Technical preparation work according to the requirements of the technical design document; Communication plan during field work.
6 Plane control measurement
6. 1 General provisions
Before the control measurement, the existing control point results in the survey area should be collected. All existing control point results that meet the accuracy requirements of this specification can be used as points of the same level.
6.1.1 Plane control points should be developed on the basis of national geodetic control points. For example, in areas without national geodetic control points, an independent control network can be established.
6.1.2 The layout of plane control points should follow the principle of hierarchical layout from the whole to the part, from high level to low level, and can also be expanded at the same level or laid out across levels.
6.1.3 Plane control points can be divided into primary control points, secondary control points and topographic control points according to their accuracy. 805
GB 17501—1998
6.1.4 Plane control measurement can use methods such as traverse measurement, triangulation measurement, trilateral measurement and GPS measurement. 6.1.5 Traverse measurement in this specification refers to photoelectric ranging traverse measurement, and traverse measurement shall be carried out in accordance with the requirements of 2.1.5, 2.1.6 and 2.1.7 in GB50026--1993.
6.1.6 The main technical requirements for triangulation shall be carried out in accordance with 2.1.3 and 2.1.4 of GB50026-1993. 6.1.7 The main technical requirements for triangulation shall be carried out in accordance with 2.1.8, 2.1.10 and 2.1.11 of GB50026-1993. 6.1.8 Main technical requirements for GPS measurement
6.1.8.1 When measuring plane control points using GPS, the GPS static or fast static relative positioning measurement method is generally used; when the accuracy requirements of this standard are met, the GPS real-time phase difference method may also be used. 6.1.8.2 The main technical requirements for GPS relative measurement shall comply with the provisions of Tables 1 and 2. Table 1 Main technical requirements for GPS measurement
Control point
Control point
Satellite altitude angle!
Average side length, km
GPS receiver
Single/dual frequency
Single/dual frequency
Single/dual frequency
Observation
Carrier phase
Carrier phase
Carrier phase
Table 2 Main technical requirements for GPS measurement
Effective observation
Total number of satellites
Synchronous observation
Number of receivers
Data sampling interval
15～60
Number of observation periods
Nominal receiver accuracy is better than
10 mm±3×10-°m
10 mm±3×10-° m
10 mm±3×10-m
Point geometry intensity factor
(PDOP)
6.1.8.3GPS network should be laid out in triangulated network or traverse network, or form other independent verification conditions that can be verified. 6.2 Point selection and stone burial
6.2.1 In designing and selecting points, existing points should be fully utilized and formed into a good figure. 6.2.2 The adjacent control points should have good visibility as much as possible, and the height (or distance) of the line of sight beyond (or away from) the obstacle is greater than or equal to 0.5m. When GPS positioning is used to measure and lay out control points, some adjacent points are allowed to have no visibility. 6.2.3 Major control points should be buried with markers, or fixed objects that are not easy to destroy can be used to chisel marks and point numbers instead of buried stones. 6.3 Horizontal angle observation shall be carried out in accordance with the requirements of 2.3 of GB50026-1993. 6.4 Distance measurement shall be carried out in accordance with the requirements of 2.4 of GB50026-1993. 6.5 Recording, collation and adjustment calculation of plane control measurement results 6.5.1 The records of items and original observation data in the notebook must be clear and complete. The original field records shall not be erased or copied. When using electronic books or portable microcomputers for recording, the programs used must be identified and approved, and the original record data must be retained and archived.
6.5.2 When collating field measurement data such as horizontal angle observation, distance measurement, GPS measurement, etc., necessary corrections must be added, and calculations can only be performed after inspection.
6.5.3 Verification of triangulation
6.5.3.1 The mean error of the triangulation angle measurement of the triangulation network is calculated according to formula (1): mg=±^
Where: W—triangle closure error, (\); n
Number of triangles.
6.5.3.2 The limit values of the free terms of the triangulated network polar conditions, side conditions and azimuth conditions shall be calculated according to formulas (2), (3) and (4) respectively. 806
......(1)
Wma, ,ma,
GB 17501-1998
Wgai Fu
Wbiao Yun=±2.
Zctg\p
1'setgβ+( +()
Wbiao Yun=± 2 Vnm + ma, + m2,
Mean error of angle measurement of corresponding level, (\); transmission angle;
Relative mean error of starting side length;
Mean error of starting azimuth, (\);
Number of stations for azimuth estimation route.
6.5.4 Verification of trilateral measurement
When using photoelectric rangefinder for round-trip observation, the unit weighted mean error of distance measurement is calculated according to formula (5): 6.5.4.1
Based on μ and p: Estimate the actual mean error of distance measurement of any side, and calculate according to formula (6) : mp,=±
Where: d-
Round-trip distance measurement error, m;
Number of distance measurement sides;
p;————priori weight of distance measurement, p;=μUnit weighted mean error of distance measurement.
, is the priori mean error of distance measurement, which can be calculated according to the nominal accuracy of the distance meter; 6.5.4.2 Check the difference between the observed value of an angle in the three-sided network and the angle value calculated by the distance measurement side: According to the average distance measurement relative mean error check of each side, the limit error is calculated according to formula (7): W\ =±2 N
(ctg\αa +ctg\β + ctga · ctgβ)+ m' Where: α, β are the other two angles in the triangle other than the observation angle; mg
the corresponding level of angle measurement error, (\); the average relative error of the distance measurement of each side.
6.5.4.3 The three-side network angle conditions, including the verification of the free terms of the circular angle conditions and the combined angle conditions, are calculated according to the formula (8): W\用充=± 2mp √aa]
Where: mp-
the average error of the distance measurement of the observed side, mm; a coefficient of the equation of the circular angle condition or the combined angle condition. 6.5.5 Verification of traverse measurement
The angle measurement error is calculated according to the formula (9).
Where: fs the azimuth closure error of the attached traverse or closed traverse loop, \); n—calculated f The number of stations;
N The number of attached traverses or closed traverse loops. · (2)
· (3)
(4)
(5)
· (6)
++(7)
(8)
(9)
GB175011998
6.5.6 The verification of GPS static relative measurement results shall be carried out in accordance with 11.1.5 and 11.1.6 of CH2001-1992. 6.5.7 The results of the primary and secondary plane control and topographic control measurements shall be strictly adjusted according to the least squares principle. 6.5.8 The position of the internal calculation numbers shall comply with the provisions of Table 3. Table 3 Internal calculation digital position
Horizontal angle observation direction value Various correction numbers
Height control measurement
7.1 General provisions
Side length observation value and various correction numbers
Side length and coordinates
Azimuth
7.1.1 The height system of the survey area adopts the "1985 National Height Datum". In areas where there is an elevation control network, the original height system can be used; when joint measurement in remote survey areas is difficult, an assumed height system can be used, or the height datum can be determined through tide measurement, water level observation and other methods. 7.1.2 The elevation control measurement level is divided into four levels and two levels beyond the level. Each level can be used as the primary elevation control of the survey area as needed. 7.1.3 Leveling, electromagnetic wave ranging trigonometric elevation measurement and GPS leveling can be used for elevation control measurement. 7.1.4 The primary network should be laid out as a ring network. When the network requires encryption, it should be laid out as a conforming route or node network. Only in special difficult circumstances is it allowed to lay out branches.
7.2 Leveling
7.2.1 The main technical requirements for leveling should comply with the provisions of Table 4. Table 4 Main technical requirements for leveling
Mean error of height difference per dry meter, mm
Accidental mean error
Total mean error
Number of observations
Joining with known
points
Round trips
Round trips
Attachment or loop
One time
One time
Discount value, closure error limit||tt ||Section, measuring section round trip
Height difference discrepancy value
±20VR
±30／R
Applicable route or
Loop closing error
±20／
Note: R is the length of the section or measuring section, L is the length of the applicable route or loop, and K is the length of the measured section, all in km. 7.2.2 The level and level rod used in leveling shall comply with the following provisions. 7.2.2.1 The angle between the sighting axis of the level and the axis of the level tube shall be less than or equal to 20\. 7.2.2.2 The difference between the average length of the meter interval on the level rod and the nominal length shall be less than or equal to 0.5mm. 7.2.2.3 When using a compensated automatic level, its compensation error shall be less than or equal to 0.2\. Detect the height difference of the measured line
segment
7.2.3 Each survey area should bury leveling points according to the size of the scope and engineering needs. It can also use stable buildings or natural features to carve out marks instead of leveling points. Leveling points should be set above the highest tide line, and the point position should be easy to find, preserve and measure. There should be 2 to 3 leveling points in a survey area and its surroundings. Newly buried leveling points need to be stabilized for more than one day before observation. For each level of leveling points, point records should be drawn and indicator stakes should be set when necessary.
7.2.4 The main technical requirements for leveling observations should comply with the provisions of Table 5. 808
Instrument type and
Line of sight length
DS,≤150
DS;≤100
DS:≤100
Line of sight difference
Front and rear sight
Cumulative difference
GB17501—1998
Technical requirements for leveling observation
Kiev (red and black)
Division constant difference
Kiev (red and black)
Difference of division height difference
Left and right routes
Transfer point difference
Intermittent point
Difference of height difference
When the difference of height between two observations exceeds the limit, the measurement should be repeated. When the re-measurement results are compared with the original measurement results and the difference does not exceed the limit, the average of the three results shall be taken.
7.2.6 The internal calculation of leveling shall comply with the following provisions. 7.2.6.1 If each leveling route is measured in sections, the difference in height between the round-trip measurement section of the leveling route shall be used for calculation. The accidental mean error of elevation difference for every kilometer of leveling measurement shall be calculated according to formula (10): ma
W: accidental mean error of elevation difference, mm;
△: discrepancy between round-trip elevation difference of leveling route section, mm; L: length of leveling section, km;
n: number of round-trip leveling route sections measured
(10)
7.2.6.2 Each leveling route shall be calculated according to the corresponding route and circular closure error. The total mean error of elevation difference for every kilometer of leveling measurement shall be calculated according to formula (11):
W: closure error, mm;
L: corresponding route length when calculating each W, km; N: number of corresponding routes or closed route rings. 7.2.6.3 The leveling network shall be strictly adjusted according to the least squares principle, and the total mean error of each meter of height difference shall be calculated. 7.2.7 The location of leveling observation calculation shall comply with the provisions of Table 6. Table 6 Leveling observation calculation location provisions
Surveying station reading
7.3 Photoelectric ranging trigonometric height measurement
7.3.1 Layout principle
Total of round-trip depth difference
Mean of round-trip height difference
Correction of orthometric height and ruler length
(11)
7.3.1.1 Photoelectric ranging trigonometric height control should be laid out as a connecting route or height wire network between high-level points. The fourth level should start and end at a height point not lower than the third level; the outside level should start and end at a height point not lower than the fourth level. In some difficult areas, branch lines can also be used to lay out the outside level height control points.
7.3.1.2 The length of the side of the elevation route should not exceed 1km, the number of sides should not exceed 6, and the number of sides of the branch line should not exceed 3. When the length of the side does not exceed 0.5km or is used for elevation control alone, the number of sides can be doubled. 809
GB17501-1998
7.3.1.3 Photoelectric ranging trigonometric height measurement can be used in combination with the same leveling measurement, but only one method can be used in the same measurement section. 7.3.2 The main technical requirements for photoelectric ranging trigonometric height measurement should comply with the provisions of Table 7. Table 7 Main technical requirements for photoelectric ranging trigonometric height measurement Grade
Number of rounds
Middle wire method
Note: D is the length of the electromagnetic wave ranging side, km
Three wire methodwwW.bzxz.Net
Poor index difference
Poor vertical angle
Poor difference in height difference in opposite observation Adhesion or ring closure difference mm
7.3.3 Photoelectric ranging trigonometric height measurement should adopt opposite observation, which should be carried out in a short time. When calculating, the influence of the earth's curvature and refraction difference should be considered.
7.3.4 The side length of trigonometric height measurement should be determined by a distance meter with an accuracy of not less than Class 1. The fourth grade should adopt one round trip each; the other grades should adopt one round trip.
7.3.5 The instrument height, reflector height or beautiful card height should be measured twice with a steel ruler, accurate to 1mm, and the middle number should be used when the difference between the two times is less than or equal to 4mm.
7.3.6 When doing internal calculations, the vertical angle should be accurate to 0.1\, and the elevation should be accurate to 1mm. 7.3.7 The adjustment calculation regulations for photoelectric ranging trigonometric height control shall be carried out in accordance with 7.2.6. 7.4 Cross-sea height measurement
7.4.1 The cross-sea height measurement in this standard refers to the joint sea level measurement that uses the average sea surface characteristics to transfer height. Cross-sea leveling using optical instruments shall be carried out in accordance with the provisions of Chapter 7 of GB12898-1991; photoelectric ranging trigonometric height measurement shall be carried out in accordance with 7.3. 7.4.2 The accuracy of cross-sea height measurement shall be negotiated with the engineering department, and the principle is to meet the accuracy requirements of the engineering design. Generally, no grade division is made, but there must be verification conditions, and the accuracy of the measurement results shall be evaluated. 7.4.3 The tide, meteorological, tide gauge station and other data of the survey area and the adjacent sea area and the land elevation control measurement data of the survey area should be fully collected and analyzed, and the accuracy requirements for elevation measurement should be put forward and determined by technical documents. 7.4.4 According to the accuracy requirements and the nature of the project, short-term tide gauge stations or temporary tide gauge stations can be set up for joint measurement of sea level. 7.4.5 The establishment of tide gauge stations, the joint measurement of tide gauge stations and level points and the requirements for water level observation should be implemented in accordance with 9.1. 7.4.6 Internal calculations for sea level measurement. 7.4.7 More than one long-term tide gauge station in the adjacent sea area should be collected and correlated with the water level observation data during the joint measurement period. When the correlation coefficient is greater than 0.75, it will be included in the calculation and used as a verification condition. 7.4.8 Regression analysis should be used to calculate the zero point elevation of the water gauge of an unknown tide gauge station at sea. When using the univariate regression analysis method, the correlation coefficient should be calculated; when using the binary regression analysis method, the accuracy analysis and significance test should be carried out according to Appendix A1. 7.5 GPS leveling
7.5.1 GPS leveling can be used to measure fourth-order and non-fourth-order elevation control points. 7.5.2 GPS leveling points should be arranged in a grid, loop or attached route. 7.5.3 GPS leveling should be carried out in accordance with the provisions of D-level measurement in CH2001-1992. 7.5.4 Depending on the size of the survey area and the elevation fluctuation, at least 4 or no less than 1/5 of the total number of GPS points with high-level known elevation control points should be measured jointly; when the elevation fluctuation is large, the number of joint measurement points should be increased, and the joint measurement points should evenly control the entire survey area. 7.5.5 GPS leveling should submit the following results: the overall adjustment result of GPS measurement;
-elevation anomaly map of the survey area;
normal elevation and accuracy assessment of the measuring points. 810
8Navigation positioning
8.1 General Provisions
GB 17501 --1998
8.1.1 In marine engineering surveying, depending on the conditions of the equipment and the working sea area, the following navigation and positioning methods are mainly selected: microwave ranging positioning method;
GPS positioning method;
other positioning methods.
8.1.2 The requirements for positioning accuracy shall be in accordance with 4.4.3. 8.1.3 Select or lay out control points above the second level as shore reference stations or survey stations. 8.1.4 The requirements for the coordinate system and projection selection of navigation and positioning shall be in accordance with 4.3.1 and 4.6.1. 8.1.5 The instrument sighting center or antenna center shall coincide with the positioning center, and its eccentricity shall not exceed 1/3 of the positioning accuracy, otherwise an eccentricity correction shall be made.
8.2 Microwave ranging positioning system positioning
The microwave ranging positioning system shall have at least two shore stations. The microwave line of sight distance between the shore station and the ship station shall be calculated according to formula (12): S=4.12( VH,+VH,1
Where: S is the microwave line-of-sight distance, km;
is the transponder elevation of the shore station and the ship station, respectively, in m. 8.2.2 When setting up shore station and ship station antennas, the influence of the surrounding environment should be fully considered to ensure the normal transmission and reception of signals. (12)
8.2.3 The instrument height should be measured and the time should be noted each time the shore station is set up and the instrument height is changed during work. The instrument height should be measured twice, and the difference between the two should not exceed 2 cm. The median should be used.
8.2.4 The ship station instrument height refers to the vertical distance from the ship's waterline to the antenna receiving center. It should be measured twice, and the difference between the two should not exceed 2 cm. The median should be used.
8.2.5 In order to avoid the "zero effect" (or " Ranging blind area”). After the system frequency and the height of the berth are determined, the height of the shore station can be appropriately adjusted or an anti-zero device can be used. When the distance S between the berth and the shore station satisfies formula (13), the berth will have a “zero effect”. S=2HH=/X
Where: Hship, Hshore-
-is the elevation of the berth and shore station antennas, m;
-is the microwave wavelength, m.
·(13)
8.2.6 Before positioning measurement, select two or more known triangulation points near the measurement area to calibrate the ranging factor of the microwave ranging positioning system. The corrected ranging error should meet the nominal accuracy of the instrument. 8.2.7 The slant distance S measured by the microwave ranging positioning system is converted to the Gaussian plane, and the length D is calculated according to formula (14): _H][1+ 2R(
Wherein: S'= VS2-AH\,m;
S—slope distance after various corrections, m;
AH=H±-H,m;
(Hphase+Hμ),m;
R=6356863/(1-e2sin2Bo),m;
-elevation anomaly,m;
e20.0066943216;
B.——Central latitude of the survey area, (°); Y.-
(Y+Y=),m;
（14）
△YY—Y,m.
GB 17501—1998
8.2.8 Select three or more known triangulation points near the survey area, and set up the microwave ranging positioning system after the ranging factor correction on the known triangulation points for positioning comparison. The positioning comparison error should not be greater than the positioning error calculated by formula (15). M. =± CSCw m.2+ m.
Where: M. - positioning error, m;
ms,vm.-- respectively the ranging error of the two observed distances, m; the intersection angle of the position line, ().
8.3GPS positioning
·(15)
8.3.1 When using GPS for marine engineering survey positioning, pseudo-range, real-time differential, and phase differential methods can be used for positioning. When the positioning accuracy meets the engineering requirements, post-processing differential positioning technology can be used. 8.3.2 Static or dynamic real-time positioning accuracy tests should be carried out before positioning work, and the test conditions and results should be attached to the technical work report. 8.3.3 The centering error between the center of the GPS antenna of the reference station and the known coordinate point should be less than 2.5cm. 8.3.4
The basic parameter setting requirements for GPS observation of the reference station are shown in Table 8. Table 8 Basic parameter settings for GPS reference station observation Number of observation satellites
Differential data output interval
8.3.5 The GPS antenna of the ship should be installed at a high place to minimize the influence of multipath effect and without SA
8.3.6 In navigation positioning, the WGS-84 coordinate system can be converted accordingly according to the actual needs of the project. 9 Depth measurement
9.1 Water level control
9.1.1 Types of tide stations
Long-term tide stations should have continuous observation data for one year or more; short-term tide stations should have at least 30 days of continuous observation; temporary tide stations should be set up during depth measurement; satellite elevation angle
≥5°
A fixed-point tide station at sea should at least observe 24h or 15d of water level data synchronously with relevant long-term or short-term stations during the spring tide (good date). The selection of good dates shall be carried out according to Appendix B. 9.1.2 Density of tide stations
The density of tide stations should be able to control the tidal changes in the entire measurement area. The distance between adjacent tide stations should meet the requirements that the maximum tidal height difference is less than or equal to 0.4m, the maximum tidal time difference is not greater than 1h, and the tidal properties should be basically the same. 9.1.3 When using the tidal data observed by relevant units, the following contents should be understood: the model, observation method and accuracy of the tide gauge; the location and stability of the leveling point, and its relationship with the zero point of the water gauge and the zero point of the tide gauge station (i.e. the zero point of the water level); the depth reference surface used; the calibration of the clock and watch; whether the observation was interrupted during the station establishment. 9.1.4 Principles for site selection of tide gauge stations
9.1.4.1 There should be no shoal blocking in front of the water gauge, the seawater can flow freely, and the low tide does not dry out, which can fully reflect the tidal wave propagation situation in the local sea area.
9.1.4.2 The fixed tide gauge station at sea should be selected in a place with a flat seabed, muddy bottom, small wind, waves and currents. 9.1.5 Requirements for the establishment of the water gauge
The established water gauge should be firm, vertical to the water surface, not submerged at high tide and not dry out at low tide; the connecting parts of the two water gauges should overlap by at least 0.3m. 9.1.6 Leveling at tide gauge stations
GB 17501-1998
9.1.6.1 A working level point should be buried near each tide gauge station in a geologically solid and stable place. 9.1.6.2 The working level point can be marked by chiseling on rocks, fixed docks, concrete surfaces, stone walls, and then marked with paint. If the above conditions are not met, solid wooden stakes can also be buried.
9.1.6.3 The working level point shall be measured in conjunction with the national level point according to the requirements of fourth-class leveling. 9.1.6.4 The level points and triangulation points near the tide gauge station can be used as working level points after inspection. 9.1.6.5 The zero point of the water gauge can be measured in conjunction with the working level point according to the requirements of the basic leveling. 9.1.6.6 During the water level observation, if it is found or suspected that the zero point of the water gauge has changed, the height difference measurement should be carried out. When the zero point of the water gauge changes by more than 3cm, the relationship between them should be re-determined and a new scale number should be assigned. 9.1.6.7 When the zero point of the water gauge of a fixed tide gauge station at sea cannot be measured by leveling, the elevation measurement method can be carried out according to 7.3, 7.4 and 7.5.
9.1.6.8 Different zero points of the water gauge at the tide gauge station should be normalized to the unified zero point of the tide gauge station. 9.1.7 Time requirements for water level observation
During the sounding, the observation time interval is less than or equal to 30min. The number of water level observations should be appropriately increased before and after high and low tides, and the time interval should be based on the principle of not missing the extreme water level value of the tide level.
9.1.8 Meteorological observation
During the water level observation, meteorological observations (wind direction, wind force, air pressure) should be carried out at 1h, 7h, 13h and 19h, and the weather conditions (cloudy, rainy, sunny, snowy) should be recorded.
9.1.9 Calibration of tide gauge clocks
Tide gauge clocks shall be calibrated with Beijing Standard Time at least once a day. 9.1.10 Requirements for water level observation readings
Water level observation readings shall be read to centimeters, with an error of less than or equal to 1cm; when the wind and waves are strong and the error of the water gauge reading is greater than 5cm, work shall be stopped.
9.2 Depth measurement
9.2.1 Laying out of sounding lines
The direction of the main sounding line shall be perpendicular to the general direction of the isobaths when using a single-beam sounder; when using a multi-beam sounder, it shall be parallel to the general direction of the isobaths in principle; for narrow waterways, the direction of the sounding line may be at an angle of 45° to the isobaths. In the following cases, the requirements for laying out the sounding line are as follows.
9.2.1.1 Radial lines should generally be laid out at the extension of sand spouts and stone embankments. If it is difficult to determine the extension range after laying out the radial lines, a sounding line parallel to its contour line should be laid out appropriately. 9.2.1.2 Spiral sounding lines should be laid around reefs and small islands in important sea areas. 9.2.1.3 For sawtooth coasts, the sounding lines should be at an angle of 45° to the general direction of the coastline. 9.2.1.4 Starting from 1~2m outside the dock wall, 2~3 sounding lines should be laid out parallel to the dock wall every 2mm on the map. 9.2.1.5 When using a multi-beam acoustic system for full coverage sounding, the lines should be laid out according to the water depth and instrument performance to ensure that there is a 10% overlap between the lines.
9.2.1.6 Other marine projects may adopt other layout methods according to actual needs. 9.2.2 Sounding line interval
The determination of the sounding line interval should take into account the importance of the sea area, the characteristics of the seabed topography and the depth of the sea water. In principle, the interval between the main sounding lines is 1cm~2cm on the map. The interval between the spiral sounding lines is generally 0.25cm on the map. The maximum spacing of the radial lines is 1 cm on the map, and the minimum spacing is 0.25 cm on the map.
9.2.3 Spacing between measuring points
Spacing between measuring points is 1 cm on the general map. The spacing should be appropriately increased in areas with significant changes in seabed topography, and can be appropriately relaxed in areas with flat seabed or water depth exceeding 20m.
9.2.4 Layout of inspection lines
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