对于竖井开挖 ，尤其是大断面 深竖井开挖 ，出碴这一环节 ，往往是决定掘进速度快慢的关键因素。
The spoiling is a key factor influencing the advance speed for the shaft excavation, especially for the excavation of large cross section and deep shaft.
此外，覆盖土的厚度、隧道线形、掘进距离、工期、竖井用地、邻近构造物等调查也至关重要。
Besides, it points out that it is also important to survey the cover coat thickness, the tunnel line shape, the dig in distance, the working …
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