Construction sequence of trench cleaning and excavation: construction preparation, survey and setting out, drainage ditch, mechanical combined with manual excavation, manual slope repair and completion acceptance.

Ditch dredging construction method:

A longitudinal drainage ditch is dug outside the silt in the drainage backbone ditch, so that water can flow back into the ditch, and soil is piled up along the ditch to form a ridge, and a small amount of river water can be discharged through the ditch. When dredging, clean it from top to bottom or from bottom to top respectively. This time, vehicles can pass through the drainage backbone ditch during the day and at night, so the dredging construction is arranged reasonably according to the silt amount and construction period. There is no big traffic road along the pond road, and the road conditions in some sections are poor, which makes it inconvenient for earthwork vehicles to pass, so the dredging efficiency is not high. Therefore, it is necessary to consider increasing transport vehicles and night construction. When the river is dredged, the river silt is manually dredged and transported ashore, and then the earth is cleaned and dredged by excavators, loaders and cars. When removing silt, immediately send someone to clean up the scattered earthwork on the road to provide a good living environment for the surrounding residents. The silt in the drainage backbone ditch in this section can only be excavated manually, then transported to the top of the green belt slope manually, and finally transported out by transportation machinery. According to the measurement,

This part of the project quantity accounts for 40% of the total project quantity. In other canal sections, we consider using digging machinery to directly dredge silt, but there is no river lane in the whole section of the river. We consider using silicon blocks to lay temporary downstream lanes at appropriate locations in the river. According to the site conditions, it is necessary to set up three downstream lanes. After the silt in the riverbed is removed, the downstream channel will be manually removed.

Trench excavation construction method:

The ditch shall be constructed by manual excavation and excavator excavation at the end of the ditch. During construction, pile inspection shall be carried out in strict accordance with the elevation and axis control, and the elevation, groove geometry and slope shall meet the design requirements. When it is close to the elevation of the ditch bottom, it will be trimmed manually to avoid over-excavation. Before trench excavation, control horizontal plate shall be used to check the center line, sideline and slope of the trench, and excavation can only be carried out after it is confirmed to meet the design requirements. During excavation, attention should be paid to the protection and retest of standard piles and horizontal slabs. During excavation, control piles should be strictly checked to ensure that the elevation and slope meet the design requirements. When the trench is excavated to the bottom of the trench, temporary piles should be added at the bottom of the trench to control the elevation, so as to prevent the natural soil layer from being destroyed due to excessive excavation. Generally, the deep soil layer of 100mm can be temporarily left when the trench is dug near the elevation, and the concrete soil at the bottom of the trench can be cleared and leveled during construction. During excavation, the distance between the earth pile and the mechanical pile and the edge of the trench should be kept at 1m to ensure the stability of the slope.