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。施工实践表明，该坍方处理方案安全、合理、可行，效果良好。可为类似地质条件下的施工提供借鉴和参考。

 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. The situations, reasons and treatment construction plan of the collapse are presented. The construction practice shows that the collapse treatment plan is safe, reasonable and feasible and good results are achieved. The paper can provide reference for works construction under similar conditions in the future.