Discussion on construction technology of channel dredging project

In the process of social and economic development, the transportation industry occupies a crucial position, and waterway is one of the important transportation channels. In order to improve the construction quality of waterway dredging project, this paper discusses the construction technology of waterway dredging project based on the characteristics of waterway operation.

Based on the characteristics of channel dredging projects with intensive capital and technology, it is very important to make a reasonable allocation of relevant construction technology in the course of channel dredging project implementation. The construction personnel of channel dredging should make a comprehensive analysis according to the construction standards of channel dredging engineering and the planning of channel construction area, and formulate a perfect construction design scheme based on the specific construction environment, so as to minimize the risk of channel dredging construction and improve the environmental benefits of the project.

1. Preparation for waterway dredging

 1.1 Setting-out survey

In the course of setting-out survey, the channel depth is evaluated in detail by using relevant measuring equipment, such as SDH-13d sounder, global positioning system, etc. Before the setting-out survey is carried out, the hydrological weather should be chosen as smooth as possible to ensure that the measuring accuracy of relevant measuring instruments is not affected. In the actual measurement process, the precast slab or concrete can be used to make buoys, which can not only ensure the measurement accuracy but also reduce the cost of the channel dredging project.

 1.2 Site layout

Site layout shall be conducted in accordance with the relevant specifications of the bidding materials for waterway dredging project, and in combination with the guiding principles of safety, reliability, ease of management, reduction of interference and smooth transportation. Considering regional water conservancy culture, urban overall planning, lake protection planning and other factors comprehensively, the construction site layout is carried out on the premise of maintaining the previous water system ecosystem. Channel dredging project is very professional. In the actual construction layout process need to choose reasonable dredging equipment. Choosing the appropriate wringing suction ship and it needs to be reasonable configuration grab ship, mud pump, blowing mud ship, etc., to ensure the smooth development of the overall construction at the same time according to the blowing distance and contract requirements.

2. Construction technology of channel dredging project

 2.1 Construction process management

First of all, in the process of starting the trial excavation, it is necessary to organize personnel with strong practical operation skills. Comprehensively consider the dredging impacts and quality of the channel soil, and reasonably regulate the parameters of the soil excavation equipment such as the main engine speed, lateral movement speed, gear shifting, mud concentration, cutting thickness, etc.

Secondly, the lowering depth of grab, reamer, and other components of the dredging equipment should be reasonably controlled according to the relevant data in the dredging process. Meanwhile, measures such as dredging leakage and back silt cleaning can be used to increase the excavation depth. The super-depth groove has a great influence on the actual construction. Therefore, according to the characteristics of the scale of dredging project, the upper layer can be used to dig the first and later dredging process. In the process of the trenching process, the lateral moving speed of trenching equipment and the ultra-deep groove should be gradually slowed down to maintain the stable operation of the whole system. In order to ensure the accuracy of groove excavation, after the relevant groove excavation is completed, it shall be overlapped with other grooves, and then layered construction shall be carried out successively. In order to ensure the trench excavation depth to meet the requirements, different back silting depths can be reserved according to the time limit of trench excavation to the completion of construction and combined with the timely quality inspection to ensure the quality of trench excavation in line with the construction standards.

Thirdly, in the mud transportation process, the operation of channel dredging vessels should be controlled, and the underground water pipeline should be laid to facilitate the orderly transportation of soil. Generally, the water diving pipe adopts the flexible connection mode, which is not only easy to sink and heave, but also can make the water diving pipe and water terrain cooperate well. In the laying process, the underwater submarine pipeline usually needs to be arranged above the water body for stage sinking. Before the actual laying, relevant equipment can be used to measure the underwater topography of the channel, so as to maintain the depth of the underwater submarine pipe above 2.6m. If the water depth is insufficient, the groove can be treated or re-dug. In order to ensure the continuous mud transportation, mud pump can be connected with mud conveying pipe to ensure the effective mud storage and transportation.

Finally, according to the characteristics of dredged soil, it can be treated by blow fill measure, mud disposal measure, overflow measure and side disposal measure. The side throw measure mainly uses the auxiliary dredging measure. In the process of the friction reaction between mud and water, the energy loss is gradually reduced, and the mud and soil particles continue to sink from coarse to fine. After the overall energy consumption, the mud is deposited and becomes an integral part of the riverbed. However, some mud particles with small mass expand into the water with the increase of flow velocity, and the mass of mud particles is inversely proportional to the bypass effect of mud. Therefore, in order to improve the mud deposition rate, on the basis of increasing the flow rate, a certain inclination Angle can be set between the channel and the flow direction to improve the mud edge casting effect. In the underwater mud throwing measure, attention should be paid to the selection of water areas. Generally, the water areas with large volume and small velocity should be selected, and the surrounding building facilities should be considered to be in good operation and free from congestion, such as hydraulic structures, grooves and waterways. Short distance excavation sites should be selected as far as possible to provide efficiency of soil delivery. In order to facilitate the effective operation of mud throwing equipment, attention should be paid to the mud throwing area of water depth and water area. The overflow measure mainly uses the mud pump to suck out the mud and make it enter the mud tank, and then the extra mud can enter the underwater from the overflow port on both sides of the mud tank. This measure can effectively prevent small and medium particles of mud from entering the mud tank. When the mud tank reaches the rated limit, it can be treated by mud throwing measure, so as to avoid the excavation of groove back to silt. Due to the change of function and property in the process of discharging mud, it can be diffused in a certain water basin, providing a guarantee for the improvement of the quality of side throwing construction. The dredging measure is mainly used to transport the excavated soil to the filling area. The dredging measure can not only effectively treat the dredged soil, but also improve the comprehensive utilization efficiency of soil and reduce the risk of dredged soil returning to the silt channel. The excavation direction should be reasonably selected before the implementation of the blowdown measure.

 2.2 Quality acceptance

After the completion of the channel dredging project, it is necessary to carry out such operations as the drawing of the punching surface of the completed and accepted section of the channel, internal data processing and external measurement. The section drawing for completion and acceptance of waterway mainly includes section drawing and section plan. The CAD network platform is mainly used to construct the spatial data of the overall construction topography, engineering application, geological culture, earth and stone works and other data. In this way, the data mapping and database establishment can be effectively integrated to ensure the smooth drawing of channel section after the completion of channel dredging project. In the field survey, the distance information of channel dredging section is compiled by collecting the topographic data of water shorelines and underwater topographic data, which should be combined with the effective application of channel section plans and sections such as triangle network and contour line.

3. Conclusion

In conclusion, the smooth implementation of channel dredging project is of great significance to the effective improvement of channel operating environment. Based on the characteristics of waterway operation, in the actual construction process, construction management personnel should carry out reasonable application of various construction technologies in combination with the planning situation of waterway water, so as to guarantee the construction quality in an all-round way.