Due to the sudden change of the geological conditions,collapse occurs to the exit section of Nama tunnel,which is an integral part of Qian-Gui railway capacity-expansion and reconstruction works.

• 详细介绍了黔桂铁路扩能改建工程中那马隧道由于地质突变导致隧道出口坍方的基本情况、坍方原因和坍方处理施工方案。