排水管管沟开挖
Excavation of drainage pipe trench
根据现况管线的分布和实际地质情况，采用人工和机械开挖两种方法，对管线埋深较浅和管径较小的工段采用人工进行管沟开挖；用机械和人工开挖分别采用1:0.25和1:0.33的放坡系数,开挖沟底比设计基底每侧加宽0.5m，以保证基础施工和管道安装有必要的操作空间，开挖弃土置于挖沟槽边线1m以外，以减少坑壁荷载，避免对坑壁的扰动，保证基坑稳定；沟槽开挖期间还将加强对其标高的测量，以防止超挖。采用机械开挖时，将用挖掘机沿开挖管线进行反铲开挖，开挖至设计管底标高以上0.2m时，即停止机械作业，改用人工开挖至设计标高。
According to the current distribution of pipelines and the actual geological conditions, the manual and mechanical excavation methods are adopted to excavate the pipe trench for the sections with shallow buried depth and small pipe diameter; the grading factors of 1:0.25 and 1:0.33 are adopted for mechanical and manual excavation respectively, The trench bottom is 0.5m wider than each side of the designed base to ensure the necessary operation space for foundation construction and pipeline installation. The excavated spoil is placed 1m away from the side line of the trench excavation to reduce the load on the pit wall, avoid disturbance to the pit wall, and ensure the stability of the foundation pit. During the trench excavation, the elevation measurement will be strengthened to prevent over excavation. When mechanical excavation is adopted, backhoe excavation will be carried out along the excavation pipeline with excavator. When the excavation reaches 0.2m above the design pipe bottom elevation, mechanical operation will be stopped and manual excavation will be used to reach the design elevation.