The excavation of the rock mass will have a great influence on the characteristics of the caverns under extremely bad geological conditions. According to the characteristics of the engineering geology, several groups of the caverns are designed to be excavated in the rock mass with three sets of through joints. Based on the summary of the failure mechanism and the failure pattern, the classification method of the failure modes is done for the flat large-span underground cavern with three sets of through joints. The classification method takes into account the control factors of the surrounding rock instability, failure mechanism, distribution of the disturbed zone, and characteristics of the rock weakness, etc. The failure modes of the flat large-span caverns contain six types: the relatively stable, the partial area falling, and the partial collapse of vault, the zigzag failure of rock stratum, the V-shaped failure, and the large-scale collapse. The change law of the vertical stress is first increasing and then decreasing for the surrounding rock in the disturbed zone. The horizontal stress shows an exponential change trend with an increase in the distance from the vault. Influenced by the failure degree of the caverns, the change law of the vertical displacement for the vault can be divided into two types. The horizontal displacement decreases with an increase in the distance from the sidewall, and there is an exponential relationship between them.

中文翻译：

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节理岩体中扁平大跨度洞室的稳定性评价

在极端恶劣的地质条件下，岩体的开挖将对洞穴的特征产生很大的影响。根据工程地质特点，设计了三组贯通缝在岩体中开挖几组洞穴。在总结了破坏机理和破坏模式的基础上，对三套贯通节点的扁平大跨度地下洞室进行了破坏模式分类。分类方法考虑了围岩失稳的控制因素，破坏机制，扰动带的分布以及岩石弱点的特征等。平坦大跨度洞室的破坏模式分为六种：相对稳定的，部分区域下降，拱顶部分塌陷，岩层之字形破坏，V形破坏和大规模塌陷。扰动区内围岩的竖向应力变化规律是先增大后减小。水平应力随着离金库距离的增加而显示出指数变化趋势。受洞室破坏程度的影响，拱顶垂直位移的变化规律可分为两种。水平位移随着距侧壁的距离的增加而减小，并且它们之间存在指数关系。扰动区内围岩的竖向应力变化规律是先增大后减小。水平应力随着离金库距离的增加而显示出指数变化趋势。受洞室破坏程度的影响，拱顶垂直位移的变化规律可分为两种。水平位移随着与侧壁的距离的增加而减小，并且它们之间存在指数关系。扰动区内围岩的竖向应力变化规律是先增大后减小。水平应力随着离金库距离的增加而显示出指数变化趋势。受洞室破坏程度的影响，拱顶垂直位移的变化规律可分为两种。水平位移随着与侧壁的距离的增加而减小，并且它们之间存在指数关系。