1.0.1 This Code is formulated with a view to unifying technical standards of dredging engineering, enhancing work quality and technical level of design and construction of dredging engineering and adapting to dredging development and engineering management requirements.
1.0.2 This Code is applicable to the design and construction of capital and maintenance dredging and reclamation engineering along the coast, at inland ports and channel. Such engineering as construction of artificial island, beach protection and bank protection, excavation and coverage of submarine pipe ditch as well as water resources dredging, environmental dredging and sand excavation may refer to this Code. This Code is not applicable to reinforcement of reclamation foundation.
1.0.3 The design and construction of dredging engineering shall not only comply with those specified in this Code, but also shall meet the requirements of JTJ/T 320 Classification of Rocks and Soils to be Dredged, JTJ/T 321 Standard for Measuring of Quantities of Soils and Rocks in Dredging Works, JTJ 203 Specifications for Port and Waterway Engineering Survey and JTJ 312 Technical Code of Regulation Works for Navigation Channel etc.
2 Terms
2.0.1 Dredging engineering
Underwater earthwork excavation engineering conducted in order to widen and deepen water area by manpower, hydraulic or mechanical method.
2.0.2 Reclamation
The operation of conveying the sand excavated by a dredger to designated place via discharge pipeline.
2.0.3 Capital dredging
Constructed, renovated or extended dredging for opening new channel and port etc. or increasing their dimensions and improving navigation conditions.
2.0.4 Maintenance dredging
Dredging of removing underwater deposits in order to maintain or restore the original dimension of a certain designated water area.
2.0.5 Low cost dredging
Dredging operation conducted by simple dredging equipment or dredging method.
2.0.6 Fluid mud layer
A silt layer between upper-layer clear water and river bottom or seafloor, consisting of flocculated sludge and of specified density and fluidity.
2.0.7 Over-depth
Depth increased from design depth due to construction error, in order to reach designed dredging depth.
2.0.8 Calculated over-depth
Calculated average over-depth counted in dredging engineering quantity in accordance with the design or construction arrangement.
2.0.9 Allowable over-depth
Maximum over-depth allowed within the dredge area, as specified in the design in accordance with engineering property.
2.0.10 Calculated over-width
Average over-excavation width required to be increased due to construction error in order to reach the bottom width as specified in the design in accordance with the design or construction arrangement.
2.0.11 Allowable over-width
Maximum over-width allowed of the dredge area bottom, in the completion acceptance according to engineering property requirements.
3 Field Investigation and Survey
3.1 General Requirements
3.1.1 Prior to the design and construction of dredging and reclamation engineering, investigations and surveys shall be conducted at the engineering site, mainly including the following basic contents:
(1) Water depth and topographic survey;
(2) Hydrological conditions;
(3) Meteorological conditions;
(4) Geological survey and rock-soil test;
(5) Soil disposal site investigation;
(6) Dredging and environmental impact investigation;
(7) Investigation on construction organization conditions.
Detailed degree of field investigation and survey shall be determined according to such conditions as engineering property, scale, importance and available information; and sources and reliability degree of its information shall be analyzed.
3.1.2 Investigation and survey work shall meet the requirements of engineering design and construction. Large-scale or complex engineering may be conducted in two stages of design and construction.
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For small-scale engineering covering an area of less than 3×105m2, its design stage may not be divided and its scale should be adopted as 1:500~1:1 000.
3.2.2 Plan control network should be arranged in a densified way within the national-level control network. Uniform rectangular plane coordinate system of Gauss conformal projection shall be adopted. In small survey area where control system is not established, simplified method may be adopted to directionally establish independent coordinate system. In the same survey area, the same coordinate system shall be adopted.
3.2.3 "1985National Elevation Datum" shall be adopted as the elevation datum. If other elevation datum is adopted, its relationship with national elevation datum shall be obtained.
For the depth datum for survey of water depth, in coastal and tidal reach, the theoretically lowest tide level counted from multi-year mean sea level shall be adopted; in the inland river, navigational datum shall be adopted. Where other depth datum is adopted, its relationship with local elevation datum shall be obtained. For the map of the same engineering, the same datum shall be adopted.
3.2.4 In the surveying and positioning by global positioning system (GPS), GPS local engineering network shall be established as the control network of the survey area and conversion parameter of WGS-84 coordinate and coordinate system used in the engineering shall be obtained. Where the elevation measured by GPS is converted to normal height, 1985 National Elevation Datum or local original elevation system shall be adopted as its elevation system.
