工人们开挖一条壕沟，在沟内砌好隧道的衬砌，然后用土覆盖，或用最初挖出的土石方回填。

Workers excavate a trench, inside of which the lining for the tunnel is built. It is then covered over with the earth or other fill that was originally removed.

youdao

工人们开挖一条壕沟，在沟内砌好隧道的衬砌，然后用土覆盖，或用最初挖出的土石方回填。

Workers excavate a trench, inside of which the lining for the tunnel is built. It is then covered over with the earth or other fill that was originally removed.

youdao