Investigating Feedbacks Between Deformation and Groundwater Flow in a Slow Moving Landslide

在美国，山体滑坡每年夺去25-50人的生命，造成16 - 32亿美元的损失。虽然有些山体滑坡发生了灾难性的失败，但其他山体滑坡表现出缓慢的季节性滑坡，通常每年只有几厘米到几米。如何决定这两种不同的行为模式中哪一种占主导地位，仍然是滑坡力学和自然灾害预测中的关键问题。这个项目将调查被认为控制滑坡缓慢滑动的物理过程。具体地说，这个项目将测试两个假设，在加利福尼亚州圣何塞附近的一个大型的、活跃的、缓慢移动的滑坡（橡树岭土流）中，滑坡变形和地下水流动之间的反馈。第一个假设认为，沿着滑坡边缘滑动会导致渗透性的变化，这将导致水的保留和地下水流动的模式，这将鼓励未来在一个地方的失败。第二种假设认为，在缓慢移动的滑坡中，滑动引起了土壤孔隙空间的膨胀，从而降低了滑坡内的水压，从而稳定了基底滑动。这两种假设都表明，对滑动的反馈是滑坡破坏过程的基础。虽然每个假设都建立在良好的物理和实验基础上，但只有非常有限的现场数据可以检验每个假设。

In the U.S., landslides annually claim 25-50 lives and cause $1.6-3.2 billion in damage. While some landslides fail catastrophically, others exhibit slow seasonal slip, often amounting to only centimeters to meters per year. What determines which of these two differing modes of behavior dominates remains a key problem in landslide mechanics and natural hazard prediction. This project will investigate the physical processes that are thought to govern slow slip in landslides.Specifically, this project will test two hypotheses for feedbacks between landslide deformation and groundwater flow at a large, active, slow-moving landslide (Oak Ridge earthflow) near San Jose, CA. The first hypothesis argues that sliding along a landslide's margins causes changes in permeability that will lead both to retention of water and to patterns of groundwater flow that will encourage future failure in one location. The second hypothesis argues that sliding induces expansion of soil pore spaces in slow moving landslides, which reduces water pressure inside the slide and hence stabilizes basal sliding. Both of these hypotheses suggest feedbacks on sliding that are fundamental to the process of landslide failure. Although each hypothesis rests on a sound physical and experimental basis, only very limited field data exist to test each.