Interactions among topographically induced elastic stress, static fatigue, and valley incision
Interactions among topographically induced elastic stress, static fatigue, and valley incision
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地形引起的弹性应力、静态疲劳和山谷切口之间的相互作用
DOI：
10.1029/2003jf000097
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发表时间：
2004
影响因子：
--
通讯作者：
P. Molnar
中科院分区：
文献类型：
--
作者：
P. Molnar
[1] 作用在地形上的重力会产生差异应力，对于足够高、陡峭的地形，可能会破坏完整的基岩。如果静态疲劳控制压裂的时间依赖性，则景观切割和压裂之间应该存在反馈。静态疲劳的时间尺度随着不同应力呈指数下降。通过形成更深、更陡的山谷，切口会增加应力差，从而加速完整岩石的破裂。由于河流系统和山坡输送断裂岩石的能力比侵蚀完整岩石然后输送其产物的能力要容易得多，因此地形引起的断裂可能在景观演化中发挥至关重要的作用，尤其是在陡峭地形中。然而，预测对地貌学一般规则有用的差异应力似乎很困难，部分原因是应力分布敏感地取决于地形的精确形式，也许更重要的是，因为特定地形的差异应力不仅大小不同，而且泊松比的微小差异的符号也可能不同。然而，在河流能够足够快地移动河床荷载的陡峭地形中，切割的速率限制过程可能是由于重力作用在邻近地形上而导致的岩石在应力下的静态疲劳。
[1] Gravity acting on topography creates differential stress, which, for sufficiently high, steep topography, can fracture intact bedrock. If static fatigue governed the time dependence of that fracturing, a feedback should exist between incision of the landscape and fracturing. The timescale for static fatigue decreases exponentially with differential stress. By creating deeper, steeper valleys, incision should increase the differential stress and, as a result, accelerate fracturing of intact rock. Because both fluvial systems and hillslopes can transport fractured rock much more easily than they can both erode intact rock and then transport its products, topographically induced fracturing could play a crucial role in landscape evolution, especially of steep terrain. Predicting differential stress useful for general rules in geomorphology, however, appears to be difficult, in part because the stress distribution depends sensitively on the precise form of the topography and, perhaps more importantly, because the differential stress for specific topography can differ not only in magnitude but also in sign for small differences in Poisson's ratio. Nevertheless, it appears possible that in steep terrain where rivers are capable of moving bed load sufficiently rapidly, the rate-limiting process for incision might be static fatigue of the rock under stress due to gravity acting on the adjacent topography.