Some standard content:
ICS07.060
National Standard of the People's Republic of China
GB/T17501—2017
Replaces GB/T17501—1998
Specification for marine engineering topographic surveying
Specification for marine engineering topographic surveying2017-11-01Issued
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of ChinaStandardization Administration of the People's Republic of China
Implemented on 2018-05-01
Normative reference documents
Terms and definitions
Technical design
Plane control survey
Height control survey
Navigation and positioning
Bath measurement
Coastal topographic survey
Submarine scanning Survey
Inspection and acceptance
Results and data
Appendix A (Informative Appendix)
Appendix B (Normative Appendix)
Appendix C (Normative Appendix)
Appendix D (Normative Appendix)
Calculation formula for joint sea level measurement
Selection of good dates for water level observation
Determination of mean sea level and depth datum Correction of sound velocity·
GB/T17501—2017
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This standard was drafted in accordance with the rules given in GB/T1.1-2009. GB/T17501—2017
This standard replaces GB/T17501—1998 "Specifications for Marine Engineering Topographic Survey". Compared with GB/T17501-1998, the main technical changes of this standard are as follows:
Modified the scope of marine engineering topography (Chapter 1 of the 1998 edition, Chapter 1 of this edition); added terms and definitions such as marine engineering topography, coastline, 2000 National Geodetic Coordinate System, and 1985 National Height Datum (see Chapter 3);
Modified the plane coordinate system used for the measurement datum in the general provisions, and changed the national coordinate system to the 2000 National Geodetic Coordinate System (see 4.3.1, 4.3.1 of the 1998 edition); modified The general provisions of plane control surveying were revised, and the specific contents of trilateral surveying and GPS surveying were deleted. Instead, global navigation satellite system positioning surveying was used: (see 6.1, 6.1 of the 1998 edition); the requirements for photoelectric ranging traverse surveying and triangulation surveying in plane control surveying were revised (see 6.1.6, 6.1.7, 6.1.5.6.1.62 of the 1998 edition). The specific requirements for point selection and stone burial, horizontal angle observation, distance measurement, record arrangement and adjustment calculation of plane control surveying results in plane control surveying were revised, and the verification of trilateral surveying and trilateral surveying were deleted. The inspection and verification of traverse measurement were changed to quoting the relevant parts in GB50026 (see 6.2, 6.3, 6.4, 6.5, 6.2, 6.3, 6.4, 6.5 of the 1998 edition); the general provisions of height control measurement were modified (see 7.1, 7.1 of the 1998 edition); the requirements for leveling measurement and photoelectric ranging trigonometric height measurement in height control measurement were modified, and the specific content was deleted, and it was changed to be implemented in accordance with the requirements of GB12898 (see 7.2, 7.3, 7.2, 7.3 of the 1998 edition); the relevant content of GPS leveling was deleted (19 7.5 of the 1998 edition); added global navigation satellite system leveling (see 7.5); modified the general provisions of navigation positioning, replaced microwave ranging and GPS ranging with global navigation satellite system and polar coordinate positioning, and changed the requirements for the selection of control points (see 8.1, 8.1 of the 1998 edition); deleted microwave ranging positioning system positioning and GPS positioning (8.2 and 8.3 of the 1998 edition); added global navigation satellite system positioning, polar coordinate positioning, underwater acoustic positioning, and navigation software (see 8.2, 8.3, 8.4, and 8.5); modified the depth measurement The measurement requirements of the working level point in the measurement (see 9.1.6.3, 9.1.6.3 of the 1998 edition); added the technical requirements for measuring water depth using the global navigation satellite system tide gauge (see 9.1.10); revised the technical requirements for depth measurement (see 9.2, 9.2 of the 1998 edition); revised the technical requirements for bathymetric positioning (see 9.3, 9.3 of the 1998 edition); added the requirements for checking and sorting the simulation records (see 9.5.4.1); added the technical requirements for draft correction (see 9.5.5.1); revised the technical requirements for dynamic draft correction 1998 Edition); revised the production of topographic maps, changing the drawing of water depth maps to the production of topographic maps (see 9.6, 1998 Edition); deleted the production of survey original maps (9.7 of 1998 Edition); revised the relevant requirements for computer-aided mapping (see 9.7, 1998 Edition 9.8); revised the general provisions of coastal topographic survey (see 10.1, 1998 Edition 10.1); revised the method of fragmentary measurement in coastal topographic survey, and changed it to the total station polar coordinate method and the global navigation satellite system real-time dynamic method. Measurement, continuous operation of the benchmark network method for measurement (see 10.2, 1998 edition 10.2); - Added the definition of the coastline (see 10.3.1); iiKANiKAca
GB/T17501-2017
Modified the specific requirements for coastline measurement and dry beach measurement (see 10.3, 10.4, 1998 edition 10.3, 10.4); - Modified the technical design, scanning implementation, and data compilation in seabed scanning (see 11.2, 11.3, 11.4, 1998 edition 11.211. 3.11.4);
Revised the relevant contents of inspection and acceptance, and results data (see Chapter 12, Chapter 13, 12.1, 12.2, 12.3 of the 1998 edition); revised the calculation formula for joint sea level measurement (see Appendix A, Appendix A of the 1998 edition); revised the calculation formula for selecting good water level observation dates (see Appendix B, Appendix B of the 1998 edition); revised the calculation formula for determining the mean sea level and depth reference plane (see Appendix C, Appendix C of the 1998 edition); revised the calculation formula for sound velocity correction (see Appendix D. Appendix D of the 1998 edition). This standard was proposed by the State Oceanic Administration.
This standard is under the jurisdiction of the National Marine Standardization Technical Committee (SAC/TC283). Drafting unit of this standard: First Institute of Oceanography, State Oceanic Administration Main drafters of this standard: Zhou Xinghua, Yang Long, Feng Yikai, Li Zenglin, Chen Yilan, Ding Jisheng, Hu Guanghai, Wu Yongting, Tang Qiuhua. This standard was first issued in 1998, and this is the first revision. IV
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1 Scope
Specification for marine engineering topographic survey
GB/T175012017
This standard specifies the general principles, technical design, survey content, technical methods, inspection and acceptance, and results data of marine engineering topographic survey.
This standard applies to marine engineering topographic surveys at a scale of 1:500 to 1:50000. 2 Normative references
The following documents are indispensable for the application of this document. For all dated references, only the dated version applies to this document. For all undated references, the latest version (including all amendments) applies to this document. GB12319 China's nautical charts
GB12327-1998 Hydrographic survey specifications
GB/T12898 National third and fourth level leveling specifications GB/T18314 Global Positioning System (GPS) survey specifications GB/T20257.1 National basic scale map diagram Part 1: 1:5000 1:1000 1:2000 topographic map diagram GB/T20257.2 National basic scale map diagram Part 2: 1:5000 1:10000 topographic map diagram GB/T20257.3 National basic scale map diagram Part 3: 1: 25000 1: 50000 1: 100000 Topographic map diagram GB/T24356—2009 Quality inspection and acceptance of surveying and mapping results Engineering survey specification GB50026—2007 CH/T2009—2010 Technical specification for global positioning system real-time dynamic measurement (RTK) 3 Terms and definitions The following terms and definitions apply to this document Marine engineering topographic surveying The measurement of seabed topography and landforms required for coastal, offshore and island and reef engineering, as well as the detection of seabed surface obstacles. 3.2 Coastline The boundary between the sea surface and the land at the mean high tide. Note: Rewrite GB/T15918-2010 definition 2.3.10. 3.3
2000 National Geodetic Coordinate System Chinageodeticcoordinatesystem2000: CGCS2000 adopts the 2000 reference ellipsoid, a right-handed Earth-fixed rectangular coordinate system with its origin at the center of the earth. The Z axis is the reference pole direction of the International Earth Rotation Bureau, the X axis is the intersection of the reference meridian plane of the International Earth Rotation Bureau and the equatorial plane perpendicular to the Z axis, and the Y axis and the X axis form a right-handed orthogonal coordinate system [GB/T14911-2008 defines 2.32
1985 National Vertical Datum 1985, named and promulgated in 1987, using the Qingdao leveling origin and the average sea level of the Yellow Sea determined according to the tide gauge data of Qingdao Tide Station from 1952 to 1979 1
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, the starting elevation of the leveling origin is 72.260m. [GB/T14911-2008 definition 2.24]
Depth datum depth datum
The starting surface of depth in marine survey is the starting surface of depth contained in nautical charts, water depth charts and various water depth data. Note: Rewrite GB/T15918-2010 definition 2.5.6.3.6
Theoretical lowest normal lowwater The specific implementation form of the depth datum of my country's nautical charts is the lowest tidal water level that may occur in theory, and its height is calculated from the local average sea level.
4 General provisions
4.1 Tasks of marine engineering topographic survey
The purpose of conducting topographic and geomorphic surveys and obstacle detection in the sea areas where marine engineering is implemented is to provide basic topographic maps and micro-topographic data for marine engineering design and construction.
2 Contents of marine engineering topographic survey
Main contents include:
plane and elevation control survey;
water level observation;
seafloor topography mapping;
seafloor micro-topography mapping;
seafloor surface obstacle detection;
coastal, island and reef topography mapping.
4.3 Use of datum
4.3.1 Coordinate system
The plane coordinate system shall adopt the "2000 National Geodetic Coordinate System" (CGCS2000). Other plane coordinate systems may be adopted according to engineering needs, but a conversion relationship must be established with CGCS2000. 4.3.2 Elevation datum
The elevation shall adopt the "1985 National Elevation Datum". For islands and reefs far away from the mainland, the elevation datum may adopt the local average sea level. 4.3.3 Depth datum
The depth datum should adopt the "theoretical lowest tide level". If other datums are adopted according to the needs of the project, the relationship between the adopted datum and the theoretical lowest tide level and the "1985 National Height Datum" should be given. For islands and reefs far away from the mainland, the depth datum can adopt the local average sea level. 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; 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. HiiKAoNiKAca
4.4.2 Elevation Control Accuracy
GB/T17501—2017
The elevation control accuracy of the working level 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 specified in GB12898.
4.4.3 Positioning Accuracy
In depth measurement, when the mapping scale is 1:500, the mean error of the positioning point is less than or equal to 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 mean error of the positioning point is less than or equal to 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 mean error of the positioning point is less than or equal to 0.5mm on the map; for offshore positioning measurement with special requirements, the positioning accuracy shall be determined according to the design requirements of the project. 4.4.4 Depth measurement accuracy
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 less than or equal to 1% of the measured depth. 4.5 Cartographic accuracy
4.5.1 The error of the length of the outline 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 map4.5.2 The accuracy of the control point display is checked by the distance between the control points. The number of check edges for each control point should not be less than two, and the check edge intersection angle should be between 30°150°, and the edge length error is less than or equal to 0.3mm on the map. 4.6 Projection and Framing
4.6.1 The projection shall be Gauss-Krüger projection. The 1.5° band projection shall be used for the mapping scale greater than or equal to 1:2000, the 3° band projection shall be used for the mapping scale greater than 1:5000 to 1:10000, and the 6° band projection shall be used for the mapping scale less than 1:10000. Other projections may also be used according to the needs of the project. 4.6.2 Framing shall be internationally unified framing or free framing. 4.7 Graphical Symbols
The graphic symbols for sea and land areas shall meet the relevant requirements of GB12319 and GB/T20257.1, GB/T20257.2 and GB/T20257.3 respectively.
Instrument Verification
The measuring instruments used for marine engineering topographic survey shall be verified or calibrated according to the relevant requirements. They can only be used if they are qualified for verification or calibration and within the validity period.
5 Technical Design
5.1 Basis of Technical Design
The main basis for technical design includes the task book, contract, relevant laws, regulations, specifications and technical standards, as well as on-site investigation and technical equipment conditions. 5.2 Project Design
The main contents of project design include:
Survey area scope, surveying and mapping scale and division of maps; - Main technical methods and measures in surveying work: 3
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Project design book:
- Draw relevant drawings.
5.3 Professional design
5.3.1 Data collection and on-site investigation of the survey area
The following survey area data should be collected:
Social conditions, natural geography, hydrology and meteorology; working conditions such as transportation, communication, ship use and sheltered anchorage; the latest published relevant maps of land and sea areas; plane and elevation control results and their descriptions; other relevant information.
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
Based on 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 measurement method and measurement accuracy from the known elevation point to the elevation control point or tide gauge station to be measured. 5.3.2.3
Water depth measurement
The following should be considered in the design of water depth measurement: according to the needs of the project and the on-site survey, select the appropriate survey ship and survey instrument; determine the survey line interval and number according to the survey scale, and determine the survey line layout direction according to the direction of the known data contour line; 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; determine the location of the tide gauge station and the water level correction plan; determine the inspection and measurement method of the positioning system and the sounding instrument. 5.3.2.4 Coastal and island topography survey
Main contents include:
Map division;
Layout of plane and elevation control;
Determination of mapping method.
Micro-topography survey and obstacle detection
Main contents include:
Determination of survey scope;
Select appropriate surveying instruments and determine survey line layout plan according to the requirements of water depth and coverage rate of the measured sea area. 5.4 Field Implementation Plan
The following factors should be considered when determining the field implementation plan: Determine the field work time;
-Main instrument equipment:
-Technical personnel selection and division of labor;
-Vehicle and ship use plan and solution; Carry out technical preparation work according to the requirements of the technical design document; -Quality control measures and safety emergency plans during field work 6 Plane control measurement
6.1 General provisions
GB/T17501—2017
6.1.1 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 specified in 4.4.1 can be used as points of the same level.
6.1.2 Plane control points should be developed on geodetic control points. For example, in areas without geodetic control points, an independent control network can be established. 6.1.3 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. 6.1.4 Plane control points can be divided into primary control points, secondary control points and topographic control points according to their accuracy. 6.1.5 Plane control measurement can use traverse measurement, triangulation measurement and global navigation satellite system (GNSS) positioning measurement methods. 6.1.6 Traverse measurement shall be carried out in accordance with the requirements of 3.3 of GB50026-2007. 6.1.7 Triangulation measurement shall be carried out in accordance with the requirements of 3.4 of GB50026-2007. 6.1.8 When using GNSS positioning measurement method to lay out plane control points, static or fast static relative positioning measurement methods are generally used, and phase difference or precise single point positioning method can also be used. The main technical requirements and accuracy indicators of GNSS positioning measurement shall comply with the relevant provisions of GB/T18314.
6.2 Site selection and stone burial
Site selection and stone burial shall comply with the requirements of Chapter 3 and Appendix B of GB50026-2007. 6.3 Horizontal angle observation
Horizontal angle observation shall comply with the requirements of 3.3 of GB50026-2007. 6.4 Distance measurement
Distance measurement shall comply with the requirements of 3.3 of GB50026-2007. 6.5 The recording, arrangement and adjustment calculation of the survey results The recording, arrangement and adjustment calculation of the survey results shall be carried out in accordance with the relevant contents of Chapter 3 of GB50026-2007. 7 Height Control Survey
7.1 General Provisions
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 elevation system can be used; when joint survey in remote survey areas is difficult, an assumed elevation system can be used, or the elevation datum can be determined through water level observation, GNSS fitting and other methods. 7.1.2 The height control measurement should be no less than the fourth grade, and the accuracy should meet the requirements of 4.4.2. In special cases, out-of-grade leveling can be arranged: each grade can be used as the first-level height control of the survey area as needed. 7.1.3 Leveling can be used for height control measurement, three 7.1.4 The primary network should be laid out as a ring network. When the network requires to be denser, it should be laid out as a network of attached routes or nodes. Only in special difficult circumstances is it allowed to lay out branch lines.
7.2 Leveling
Leveling shall be carried out in accordance with the requirements of GB12898. 7.3 Trigonometric height measurement
Trigonometric height measurement shall be carried out in accordance with the requirements of GB12898. 7.4 Cross-sea height measurement
7.4.1 The cross-sea height measurement in this standard refers only to the sea level leveling joint measurement that uses the characteristics of the mean sea level for height transfer. Cross-sea leveling is carried out using optical instruments, trigonometric height measurement and GNSS leveling method, according to G The relevant requirements in B12898 shall be implemented. 7.4.2 The accuracy of cross-sea elevation 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 tides, meteorology, tide gauge station and other data of the survey area and adjacent sea areas and the onshore elevation control measurement data of the survey area shall be fully collected and analyzed, and the accuracy requirements for elevation measurement shall be proposed and confirmed with technical documents. 7.4.4 For joint sea level measurement, short-term tide gauge stations or temporary tide gauge stations may be established according to the accuracy requirements and the nature of the project. 7.4.5 The establishment of tide gauge stations, the joint measurement of tide gauge stations and leveling points, and the requirements for water level observation shall be implemented in accordance with 9.1. 7.4.6 The internal calculations of sea level measurement shall collect the adjacent More than one long-term tide gauge station in the sea area shall be correlated with the water level observation data during the joint survey. When the correlation coefficient is greater than 0.75, it shall be included in the calculation and used as a calibration condition. 7.4.7 Regression analysis can be used to calculate the zero elevation of the water gauge of an unknown tide gauge station at sea. When using the univariate regression analysis method, the correlation coefficient shall be calculated according to Appendix A.
5GNSS leveling
GNSS leveling shall be carried out in accordance with the requirements of 4.4 of GB50026-2007. 8 Navigation and positioning
8.1 General provisions
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 used: - GNSS positioning method;
- Polar coordinate positioning method;
- Other positioning methods.
8.1.2 The requirements for positioning accuracy shall comply with the provisions of 4.4.3. 8.1.3 Select or arrange control points above the E-level GPS points classified in GB/T18314 as reference points or control points, and use the control points to determine the coordinate conversion parameters between the coordinate system used in the project and CGCS2000 according to the project needs. 8.1.4 The requirements for the coordinate system and projection selection of navigation positioning shall be implemented in accordance with 4.3.1 and 4.6.1. 8.2 GNSS positioning
8.2.1 GNSS positioning shall adopt single-machine positioning or differential positioning according to the positioning accuracy requirements of the project. 8.2.2 Static or dynamic real-time positioning accuracy tests shall be performed on the control points before positioning work, and the test conditions and results shall be attached to the technical work report.
8.2.3 The GNSS antenna on board shall be set up in a place with good clearance conditions to minimize the impact of multipath effects. 63 Horizontal angle observation
Horizontal angle observation shall be carried out in accordance with the requirements of 3.3 of GB50026-2007. 6.4 Distance measurement
Distance measurement shall be carried out in accordance with the requirements of 3.3 of GB50026-2007. 6.5 The recording, arrangement and adjustment calculation of the survey results The recording, arrangement and adjustment calculation of the survey results shall be carried out in accordance with the relevant contents of Chapter 3 of GB50026-2007. 7 Height Control SurveybzxZ.net
7.1 General Provisions
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 elevation system can be used; when joint survey in remote survey areas is difficult, an assumed elevation system can be used, or the elevation datum can be determined through water level observation, GNSS fitting and other methods. 7.1.2 The height control measurement should be no less than the fourth grade, and the accuracy should meet the requirements of 4.4.2. In special cases, out-of-grade levels can be arranged: each grade can be used as the first-level height control of the survey area as needed. 7.1.3 Leveling can be used for height control measurement, three 7.1.4 The primary network should be laid out as a ring network. When the network requires to be denser, it should be laid out as a route-attached or node network. Only in special difficult circumstances is it allowed to lay out branch lines.
7.2 Leveling
Leveling shall be carried out in accordance with the requirements of GB12898. 7.3 Trigonometric height measurement
Trigonometric height measurement shall be carried out in accordance with the requirements of GB12898. 7.4 Cross-sea height measurement
7.4.1 The cross-sea height measurement in this standard refers only to the sea level leveling joint measurement that uses the characteristics of the mean sea level for height transfer. Cross-sea leveling is carried out using optical instruments, trigonometric height measurement and GNSS leveling method, according to G The relevant requirements in B12898 shall be implemented. 7.4.2 The accuracy of cross-sea elevation 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 tides, meteorology, tide gauge station and other data of the survey area and adjacent sea areas and the onshore elevation control measurement data of the survey area shall be fully collected and analyzed, and the accuracy requirements for elevation measurement shall be proposed and confirmed with technical documents. 7.4.4 For joint sea level measurement, short-term tide gauge stations or temporary tide gauge stations may be established according to the accuracy requirements and the nature of the project. 7.4.5 The establishment of tide gauge stations, the joint measurement of tide gauge stations and leveling points, and the requirements for water level observation shall be implemented in accordance with 9.1. 7.4.6 The internal calculations of sea level measurement shall collect the adjacent More than one long-term tide gauge station in the sea area shall be correlated with the water level observation data during the joint survey. When the correlation coefficient is greater than 0.75, it shall be included in the calculation and used as a calibration condition. 7.4.7 Regression analysis can be used to calculate the zero elevation of the water gauge of an unknown tide gauge station at sea. When using the univariate regression analysis method, the correlation coefficient shall be calculated according to Appendix A.
5GNSS leveling
GNSS leveling shall be carried out in accordance with the requirements of 4.4 of GB50026-2007. 8 Navigation and positioning
8.1 General provisions
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 used: - GNSS positioning method;
- Polar coordinate positioning method;
- Other positioning methods.
8.1.2 The requirements for positioning accuracy shall comply with the provisions of 4.4.3. 8.1.3 Select or arrange control points above the E-level GPS points classified in GB/T18314 as reference points or control points, and use the control points to determine the coordinate conversion parameters between the coordinate system used in the project and CGCS2000 according to the project needs. 8.1.4 The requirements for the coordinate system and projection selection of navigation positioning shall be implemented in accordance with 4.3.1 and 4.6.1. 8.2 GNSS positioning
8.2.1 GNSS positioning shall adopt single-machine positioning or differential positioning according to the positioning accuracy requirements of the project. 8.2.2 Static or dynamic real-time positioning accuracy tests shall be performed on the control points before positioning work, and the test conditions and results shall be attached to the technical work report.
8.2.3 The GNSS antenna on board shall be set up in a place with good clearance conditions to minimize the impact of multipath effects. 63 Horizontal angle observation
Horizontal angle observation shall be carried out in accordance with the requirements of 3.3 of GB50026-2007. 6.4 Distance measurement
Distance measurement shall be carried out in accordance with the requirements of 3.3 of GB50026-2007. 6.5 The recording, arrangement and adjustment calculation of the survey results The recording, arrangement and adjustment calculation of the survey results shall be carried out in accordance with the relevant contents of Chapter 3 of GB50026-2007. 7 Height Control Survey
7.1 General Provisions
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 elevation system can be used; when joint survey in remote survey areas is difficult, an assumed elevation system can be used, or the elevation datum can be determined through water level observation, GNSS fitting and other methods. 7.1.2 The height control measurement should be no less than the fourth grade, and the accuracy should meet the requirements of 4.4.2. In special cases, out-of-grade levels can be arranged: each grade can be used as the first-level height control of the survey area as needed. 7.1.3 Leveling can be used for height control measurement, three 7.1.4 The primary network should be laid out as a ring network. When the network requires to be denser, it should be laid out as a route-attached or node network. Only in special difficult circumstances is it allowed to lay out branch lines.
7.2 Leveling
Leveling shall be carried out in accordance with the requirements of GB12898. 7.3 Trigonometric height measurement
Trigonometric height measurement shall be carried out in accordance with the requirements of GB12898. 7.4 Cross-sea height measurement
7.4.1 The cross-sea height measurement in this standard refers only to the sea level leveling joint measurement that uses the characteristics of the mean sea level for height transfer. Cross-sea leveling is carried out using optical instruments, trigonometric height measurement and GNSS leveling method, according to G The relevant requirements in B12898 shall be implemented. 7.4.2 The accuracy of cross-sea elevation 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 tides, meteorology, tide gauge station and other data of the survey area and adjacent sea areas and the onshore elevation control measurement data of the survey area shall be fully collected and analyzed, and the accuracy requirements for elevation measurement shall be proposed and confirmed with technical documents. 7.4.4 For joint sea level measurement, short-term tide gauge stations or temporary tide gauge stations may be established according to the accuracy requirements and the nature of the project. 7.4.5 The establishment of tide gauge stations, the joint measurement of tide gauge stations and leveling points, and the requirements for water level observation shall be implemented in accordance with 9.1. 7.4.6 The internal calculations of sea level measurement shall collect the adjacent More than one long-term tide gauge station in the sea area shall be correlated with the water level observation data during the joint survey. When the correlation coefficient is greater than 0.75, it shall be included in the calculation and used as a calibration condition. 7.4.7 Regression analysis can be used to calculate the zero elevation of the water gauge of an unknown tide gauge station at sea. When using the univariate regression analysis method, the correlation coefficient shall be calculated according to Appendix A.
5GNSS leveling
GNSS leveling shall be carried out in accordance with the requirements of 4.4 of GB50026-2007. 8 Navigation and positioning
8.1 General provisions
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 used: - GNSS positioning method;
- Polar coordinate positioning method;
- Other positioning methods.
8.1.2 The requirements for positioning accuracy shall comply with the provisions of 4.4.3. 8.1.3 Select or arrange control points above the E-level GPS points classified in GB/T18314 as reference points or control points, and use the control points to determine the coordinate conversion parameters between the coordinate system used in the project and CGCS2000 according to the project needs. 8.1.4 The requirements for the coordinate system and projection selection of navigation positioning shall be implemented in accordance with 4.3.1 and 4.6.1. 8.2 GNSS positioning
8.2.1 GNSS positioning shall adopt single-machine positioning or differential positioning according to the positioning accuracy requirements of the project. 8.2.2 Static or dynamic real-time positioning accuracy tests shall be performed on the control points before positioning work, and the test conditions and results shall be attached to the technical work report.
8.2.3 The GNSS antenna on board shall be set up in a place with good clearance conditions to minimize the impact of multipath effects. 6
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