管底到坑底的距离大于500mm（石方段距离大于等于300mm），必须人

The distance from the bottom of the pipe to the bottom of the pit is greater than 500mm (the distance from the stone section is greater than or equal to 300mm), which must be carried out manually. When the soil above the weld is cleaned, manual cleaning must be used. Set up anti-collapse shed under the operation pit or use pile driving and support to reinforce the operation pit, and mechanically and manually excavate pedestrian passages with a slope of less than 15 ° along both sides of the axial end of the weld. During the excavation of the operation pit, in order to ensure the operation safety of the pipeline in service, a safety officer must supervise the whole station during the excavation process.

The distance from the bottom of the tube to the bottom of the pit is greater than 500mm (the distance of the stone section is greater than or equal to 300mm), must be carried out manually, and manual cleaning must be used when cleaning the soil above the weld. Under the operation pit, the anti-collapse shed is placed or the operation pit is reinforced with piling and support, and the axial passage smaller than 15 degrees is excavated by mechanical and manual excavation of the slope by mechanical and manual excavation at both ends of the welding port. In order to ensure the safety of the operation of the operation of the operation of the operation pit, the excavation process must have the safety personnel to supervise the side station.

The distance between the pipe bottom and the pit bottom is more than 500mm (the distance between the stonework section is more than or equal to 300mm), which must be carried out manually. When cleaning the soil above the welded junction, it must be cleaned manually. The anti collapse shed shall be placed under the operation pit or the operation pit shall be reinforced by piling and supporting. At both sides of the axial end of the welded junction, the pedestrian passage with a slope of less than 15 ° shall be excavated by machinery and labor along the axial direction. During the excavation of operation pit, in order to ensure the operation safety of the pipeline in service, the safety officer must be on site for supervision throughout the excavation process.