一种岩石节理内聚力时效性降低的断裂力学方法

A Fracture Mechanical Method for Time-independence Reduction of Rock Joint Cohesion

提出了一种断裂力学模型来论证时效性对于脆性破坏岩石的重要性。建立了一种岩石节理内聚力的时效性降低模型。利用分支裂隙扩展建立断裂力学模型,可导出节理内聚力的一种具有封闭解的时间方程。通过一个实例,分析了对于滑动面的包含许多岩桥的岩块,发现内聚力持续下降,一开始很慢,然后突然加快,当内聚力降低到某一值时导致边坡失稳。给出的第二个例子是假定某些材料参数的变化,来解决边坡破坏的概率分析,并推出破坏概率的时间方程。研究发现概率是随着时间推移而增长,从初值为5%增长到第100年时超过40%。

A fracture mechanical model is proposed to demonstrate the importance of time-dependence to brittle fractured rock. In addition, a model is developed for time-dependence degradation of rock joint cohesion. Fracture mechanical model is developed by utilizing subcritical crack growth,leading to an equation that has a closed solution for joint cohesion as a function of time. Through a real case analysis of a block containing many rock bridges subject to plane sliding, it is found that the cohesion decreases continuously, which is slow at beginning and then accelerates suddenly. The cohesion, when decreasing to certain value,will lead to slope instability. The second case is on the assumption that there are variations in some material parameters. A probability analysis of slope failure is made and the probability of failure as a function of time is predicted. It is found that the probability increases with the time, from an initial 5% increase to over 40% at the hundredth year.