1.What is the main purpose of underground pipeline systems?
1.埋地管道系统的核心作用是：
2.Excavation principles do NOT include:
2.开挖工程的核心原则不包括：
3.First step before excavation is:
3.开挖前必须完成的第一步是：
4.Excavation must comply with:
4.加州开挖施工必须遵循：
5.When must excavation permits be obtained?
5.开挖许可必须在什么时候取得？
6.Slope in soft soil areas is:
6.软土地区边坡一般为：
7.Rock excavation slope is:
7.岩层开挖坡度为：
8.Main pipeline burial depth is at least:
8.主干管埋深要求至少：
9.Branch pipe minimum depth is:
9.支管最小埋深为：
10.Subgrade bearing capacity must be:
10.基底承载力要求为：
