Methods of tunnel excavation in unconsolidated formations and the collapse zone treatment are intro-duced according to the formation properties fo exit section of Yangzong No.

• 针对阳宗海一号隧道出口段的地层特点，介绍了在松散土体地层中遂道施工方法的选择及在施工中出现坍塌的处理方法。