硐室片状危岩体病害机理分析与评价方法

Mechanism analyses and evaluation methods of schistose dangerous rock mass in cavern

长屿硐天遗址公园遗留了大量危岩体,造成较为严重的安全隐患。经现场勘查发现,长屿硐天景区存在12处片状危岩体,其结构特征和形成机理与常见的危岩体存在显著的不同。以W42危岩体为例,通过FLAC数值模拟计算,分析了片状危岩体的应力特征和卸荷作用,发现卸荷作用对开挖面3 m以内围岩影响较大;采用断裂力学方法,分析了应力强度因子K_I与岩体内原生裂隙倾角α、原始裂隙开裂角θ_0、原生裂隙长度c之间的关系和影响规律,得出了开裂角θ_0在78°左右时,岩体原生裂隙更容易扩展开裂的规律。这些规律能够较为合理地解释片状危岩体的形成机理和结构特征,以及研究区域节理多为陡倾或直立的原因。

There are many dangerous rocks in the Changyu ruins park, which will be the hidden hazards to serious safety. 12 schistose dangerous rocks are found. Its structural characteristics and formation mechanism are different from those of the common and dangerous rock mass. On the basis of detailed field investigation, the W42 dangerous rock is calculated by FLAC numerical simulation as an example, and the stress characteristics and unloading effect of the schistose dangerous rock mass are analyzed. It is found that the unloading effect is mainly influenced by the surrounding rock within 3 m of the excavation face. With the fracture mechanics method, the relationship and the influence law between the stress intensity factor K1 and primary fracture dip angle α, initial fracture fracture angle θ0, initial fracture length c are analyzed. The results show that the fracture of rock mass is more likely to crack when the crack angle 00 is about 78°. It is close to the inclination of the structural plane of the W42 dangerous rock. The stability of the W42 dangerous rock is analyzed using the stability formula. These laws can reasonably explain the formation mechanism and structural characteristics of schistose dangerous rock masses. They also explain the regional joints tendency to he steep or upright .