裂缝冰胀力作用下高寒危岩体失稳破坏机理

Collapse Mechanism of Extreme Cold Dangerous Rock at High Altitude Under Expansive Force of Crack Ice

高海拔极寒山体危岩的失稳崩塌是川藏山区最常见的山地灾害类型之一,但目前有关其力学机制还不清晰,难以很好地进行诊断和防治。为此,基于川藏高寒危岩体实际结构特征,借助岩石力学及断裂力学知识,构建了高寒危岩裂缝的冰胀力表达,分析了不同危岩体裂缝的断裂模式、启裂条件和扩展方向,并给出了扩展量的计算方法,明晰了高寒裂缝冰胀力诱发岩体崩塌的力学机制。算例分析表明,在环境升温幅度大于临界温升后,冰裂缝开始扩展,并最终在多轮季节性温度升降后贯通危岩体形成崩塌。

As one of the most common mountain hazards,the collapse of dangerous rock at high altitude with freezing temperature in Sichuan-Tibet Mountains presents a serious threat to the driver traffic safety and people survival. Based on the true structure of danger rock and based on the rock fracture mechanics,an expression was developed to calculate the expansive force of crack ice. Then by analyzing the condition and process of crack propagation,the instability mechanism of dangerous rock under ice expansive force was studied clearly. Furthermore,the calculation formula for critical rise temperature and propagation length were also suggested. At last,an example was given to prove the theory. The result showed that the cracks on danger rock can propagate and develop when the temperature rises higher than the critical value,which results in the collapse occasion at last.