Displacement mechanisms of slow-moving landslides in response to changes in porewater pressure and dynamic stress
Displacement mechanisms of slow-moving landslides in response to changes in porewater pressure and dynamic stress
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DOI：
10.5194/esurf-7-707-2019
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发表时间：
2018-10
影响因子：
3.4
通讯作者：
J. Carey;C. Massey;B. Lyndsell;D. Petley
中科院分区：
文献类型：
--
作者：
J. Carey;C. Massey;B. Lyndsell;D. Petley
抽象的。尽管缓慢移动的山体滑坡构成了巨大的危险，但人们对其详细机制的了解仍然相对较少。我们已经进行了一套创新的实验室实验，使用新的设备，以模拟一系列的孔隙水压力和动态应力的情况下，从一个缓慢移动的滑坡复杂的样品在新西兰。我们试图了解地震期间孔隙水压力和地面加速度的变化如何影响缓慢移动的滑坡的运动模式。我们的实验表明，在孔隙水压力升高期间，位移速率受两个分量的影响：第一个绝对应力状态分量（正常有效应力状态）和第二个瞬态应力状态分量（正常有效应力的变化率）。在动态剪切循环期间，位移速率由作用在剪切表面处的力超过屈服加速点处的应力状态的程度控制。结果表明，在强震加速度作用下，结构的应变会迅速增加，而不平衡力的增加相对较小。通过增加孔隙水压力产生的运动也有类似的行为。我们的研究结果表明，剪切带变形的机制如何控制大型缓慢移动平移滑坡的运动模式，以及它们如何被强震和重大降雨事件所动员。
Abstract. Although slow-moving landslides represent a substantial hazard, their detailed mechanisms are still comparatively poorly understood. We have conducted a suite of innovative laboratory experiments using novel equipment to simulate a range of porewater pressure and dynamic stress scenarios on samples collected from a slow-moving landslide complex in New Zealand. We have sought to understand how changes in porewater pressure and ground acceleration during earthquakes influence the movement patterns of slow-moving landslides. Our experiments show that during periods of elevated porewater pressure, displacement rates are influenced by two components: first an absolute stress state component (normal effective stress state) and second a transient stress state component (the rate of change of normal effective stress). During dynamic shear cycles, displacement rates are controlled by the extent to which the forces operating at the shear surface exceed the stress state at the yield acceleration point. The results indicate that during strong earthquake accelerations, strain will increase rapidly with relatively minor increases in the out-of-balance forces. Similar behaviour is seen for the generation of movement through increased porewater pressures. Our results show how the mechanisms of shear zone deformation control the movement patterns of large slow-moving translational landslides, and how they may be mobilised by strong earthquakes and significant rain events.