A multidimensional stability model for predicting shallow landslide size and shape across landscapes.
A multidimensional stability model for predicting shallow landslide size and shape across landscapes.
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DOI：
10.1002/2014jf003135
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发表时间：
2014-11
期刊：
影响因子：
--
通讯作者：
Dietrich WE
中科院分区：
文献类型：
--
作者：
Milledge DG;Bellugi D;McKean JA;Densmore AL;Dietrich WE
浅层滑坡的规模是控制其危险性和地貌重要性的根本因素。现有的模型要么无法预测滑坡的大小，要么计算量太大，因此无法实际应用于各种景观。我们推导了一个适合于自然斜坡的模型，该模型能够预测浅层滑坡的大小，但足够简单，可以应用于整个流域。它通过使用土压力理论表示作用在潜在滑坡的每个边缘上的力，并通过将根系加固表示为土壤深度的指数函数来说明侧向阻力。我们测试了我们的模型预测观测到的滑坡失败的能力，其中相关参数受到现场数据的很好约束。该模型预测了观察到的疤痕几何形状的失效，并发现较大或较小的保形形状更稳定。数值实验表明，相对于单纯的根黏聚力，潜在滑坡边界上的摩擦大大增加了侧向加固的强度。我们发现在粘性和无粘性土中都存在一个临界深度，导致最小破坏尺寸，这与观测到的尺寸-频率分布一致。此外，潜在滑坡边界上的差异阻力导致了临界滑坡形状的长度大于宽度，这与观测到的纵横比一致。最后，我们的结果表明，最小尺寸随破坏面深度的近似平方而增加，与观测到的滑坡深度面积数据一致。
The size of a shallow landslide is a fundamental control on both its hazard and geomorphic importance. Existing models are either unable to predict landslide size or are computationally intensive such that they cannot practically be applied across landscapes. We derive a model appropriate for natural slopes that is capable of predicting shallow landslide size but simple enough to be applied over entire watersheds. It accounts for lateral resistance by representing the forces acting on each margin of potential landslides using earth pressure theory and by representing root reinforcement as an exponential function of soil depth. We test our model's ability to predict failure of an observed landslide where the relevant parameters are well constrained by field data. The model predicts failure for the observed scar geometry and finds that larger or smaller conformal shapes are more stable. Numerical experiments demonstrate that friction on the boundaries of a potential landslide increases considerably the magnitude of lateral reinforcement, relative to that due to root cohesion alone. We find that there is a critical depth in both cohesive and cohesionless soils, resulting in a minimum size for failure, which is consistent with observed size-frequency distributions. Furthermore, the differential resistance on the boundaries of a potential landslide is responsible for a critical landslide shape which is longer than it is wide, consistent with observed aspect ratios. Finally, our results show that minimum size increases as approximately the square of failure surface depth, consistent with observed landslide depth-area data.