锁固段之间的力学作用模式

MODES OF MECHANICAL ACTION BETWEEN LOCKED SEGMENTS

天然锁固段主控锁固型斜坡稳定性和构造地震演化过程,其按照承载力从低到高的次序依次断裂(宏观破坏)。因此,研究某一锁固段断裂时下一个锁固段的力学响应机制,对预测后者的断裂行为具有重要意义。研究表明,锁固段在体积膨胀点处产生的高能级特征破裂事件(标志性事件)可作为该点的判识标志,亦为锁固段的断裂前兆。我们构建了剪切作用下断层中包含两个锁固段的力学模型,基于理论分析和数值模拟讨论了具有不同承载力的锁固段组合导致的力学行为,指出天然锁固段之间的力学作用遵循强作用模式,即当前锁固段被加载至峰值强度点时,再经历一个可忽略的剪切位移增量或应变增量,伴随的荷载转移可使下一个锁固段演化至其体积膨胀点。该模式能够合理解释多种地震观测现象和实验结果。

Natural locked segments dominate the stability of locked-segment-type slopes and the evolutionary process of tectonic earthquakes.They fail in order of bearing capacity from low to high.Therefore,it is very important to study the mechanical response mechanism of the next locked segment while the current locked segment is broken,and predict the fracture behavior of the latter.We found that a high-energy-level characteristic cracking event(characteristic event)at the volume-expansion point of locked segment can be viewed as both the indicator of the point and the precursor to the rupture of locked segment.We established a mechanical model consisting of two locked segments that are subjected to shear loading,discussed the mechanical behavior resulted from different combinations of locked segments bearing capacity based on the theoretical analysis and numerical simulations,and stated that the mechanical action between natural locked segments follows a strong action mode.In other words,when the current locked segment is loaded to reach its peak-stress point,the load applied to it will be transferred to the next locked segment;the load transfer with a negligible increase in shear displacement or strain can make the latter evolve to its volume-expansion point.The mode can well explain many kinds of seismic observation phenomena and experimental results.