You can choose municipal quotas, which are divided into manual and mechanical excavation. Mechanical excavation generally does not distinguish between depths. You can choose 1-215~1-256 quota sub-items. Generally, a 1m^3 backhoe excavator is used. , select fixed quota subheadings 1-233~1-238.

The depth of manual excavation can be divided into 1-4~1-15 fixed sub-items; if it is man-machine cooperation, mechanical excavation shall be considered as 90% of the total amount of excavated soil, and manual excavation shall be as excavated. 10% of the total amount of soil is considered, of which manual digging is multiplied by a factor of 1.5.

In order to save earthwork, the slope rate is too steep or the slope rate is not built according to the trench depth and soil characteristics, causing the trench side to lose stability and cause landslides.

When there is a soil layer with groundwater or surface water scouring the trough, if no effective drainage and precipitation measures are taken in advance, the soil layer will be soaked, and the shear strength index of the soil will be cohesion c and internal friction angle. β decreases, and under the action of gravity, it loses stability and collapses.

Extended information:

Dig a straight trench 50 to 100cm deep, insert the sheet piles into the guide frame, arrange them closely along the edge of the bottom trench, and hammer them into the soil manually as you dig. . Use square logs tightly against the sheet piles and cross braces against the square logs. After the trench bottoms out, the position of the cross brace needs to be adjusted.

Understand the condition of the natural drainage system and existing drainage pipes, and take measures for ground drainage and diversion. When there is groundwater within the trench excavation range, drainage measures should be taken. Lower the water level to no less than 0.5m below the bottom of the tank and maintain it until the backfill is completed.

The storage location of the trenched earth should be properly arranged. Generally, they are piled on both sides of the trench. The distance between the downslope foot of the pile of soil and the trough edge should be determined based on the trough depth, soil quality, and trough side slope. Its minimum distance is 1.0m. If you plan to transport material next to the tank. When there are motor vehicles passing through, the minimum distance is 3.0m, and when the soil is soft, it shall not be less than 5.0m.

Trench excavation should be carried out in layers from top to bottom in the vertical direction. Planely speaking, it should be carried out in sections starting from the downstream, and a certain slope should be made at any time to facilitate drainage. After the trench bottoms out, the next process should be carried out promptly to prevent disturbing the foundation.

Baidu Encyclopedia--Trenches

Baidu Encyclopedia--Earthworks

Baidu Encyclopedia--Quota Sub-item