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Analogue modelling of pre-failure strain accumulation for landslide failure prediction

用于滑坡破坏预测的破坏前应变积累模拟模型

基本信息

批准号：
NE/G000050/1
负责人：
Nicholas Rosser
金额：
$ 11.21万
依托单位：
Durham University
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2008
资助国家：
英国
起止时间：
2008 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FG000050%2F1
关键词：
Analogue modelling pre failure strain

项目摘要

Landslides are one of the most destructive geological hazards, resulting in excess of 100,000 fatalities between 1990 and 2006. There is now considerable evidence that landslide impact is increasing. These effects are focussed upon mountainous areas in developing countries, where losses can be 2 / 3% of GDP per year. To undertake a full assessment of landslide hazard, an understanding of the likely location, style, size, speed and timing of the failure is needed, but the last of these remains poorly understood; a problem well illustrated by the 17th February '06 landslide at Leyte, Philippines. This event killed more than 1,100 people and occurred on slopes previously identified as potentially unstable. Prior to the landslide ten days of intense rainfall occurred, a period during which cracks on the slopes above the village were noted. After five days of rainfall the town was evacuated, but after the cessation of rain five days later, the town was re-occupied. Disastrously, the landslide occurred shortly after. The potential for a large landslide was known, precursory signs observed, but a poor understanding of landslide timing, resulted in catastrophe. One approach to understand failure timing has been developed after observations of movements, or strains, on unstable embankments by Japanese engineer, Saito. He observed that when the inverse of velocity of deformation prior to failure was plotted against time, a straight line was observed (Saito, 1965), termed 'Saito linearity'. The implication was that the linear trend could be extrapolated to a point at which velocity reached infinity, predicting of failure. More recently, others noted characteristic movement patterns in landslides, termed 'three phase creep' Varnes (1978), in which a failing slope exhibits three distinct periods of movement. Recently attempts to understand the failure mechanisms which control this pattern have used monitoring of failing slopes and novel geotechnical testing. Questions remain surrounding the application of this model to real slopes particularly with respect to the influence of slope geometry on the evolution of failure, and the complexity of interpreting strain state from real-world monitoring data. Research is proposed to observe the influence of variations in slope geometry and strength on the mechanisms of pre-failure deformation, using a newly developed technique named a vertical 'gravity accelerator' table. In this model a slope, formed from a material with elasto-brittle-plastic properties, that at scale behaves comparably to natural slope materials, is subject to cyclic-loading by dropping onto a hydraulic ram imposing a rapid acceleration in the same direction as gravity. Hence, a 2,000 m slope is simulated using a 0.4 m scale analogue. In a series of model configurations the influence of slope angle, slope length, curvature and strength will be tested. Deformation will be monitored using a high-precision 3D structured light scanner, which measures the surface deformation. In a final set of experiments the processes acting within three well-instrumented real-world landslides will be replicated. These will be the Selbourne cutting stability experiment, UK, the Ota-Mura Landslide, Japan, and the Pos Selim Landslide, Malaysia. Using 3D printing each slope will be recreated, failure simulated and deformation results compared to monitoring data, to establish the controls on the mechanisms and evolution of failure. These data will then be compared to a new database of landslide movement collated from the literature to exmaine landslide mechanisms and movement in a large number of failures. Determining the controls of slope form and material strength on landslide mechanisms and resulting pre-failure surface deformation will give enhanced understanding of deformation trends observed in landslides, mechanisms for landslide triggering and ovement, and will have implications for the use of Saito methods for slope failure prediction.

滑坡是最具破坏性的地质灾害之一，在1990年至2006年期间造成超过10万人死亡。现在有相当多的证据表明，滑坡的影响正在增加。这些影响主要集中在发展中国家的山区，每年的损失可达国内生产总值的2 / 3%。为了对滑坡灾害进行全面评估，需要了解滑坡的可能位置、类型、规模、速度和时间，但对最后一个问题仍然知之甚少;菲律宾莱特2006年2月17日的滑坡很好地说明了这个问题。这一事件造成1,100多人死亡，并发生在以前被确定为潜在不稳定的斜坡上。在山体滑坡发生前十天的强降雨，在此期间，村庄上方的斜坡上出现了裂缝。经过五天的降雨后，该镇被疏散，但五天后雨停后，该镇又被重新占领。灾难性的是，不久之后就发生了山体滑坡。大滑坡的可能性是已知的，观察到了一些迹象，但对滑坡时间的理解不足，导致了灾难。日本工程师齐藤在观察了不稳定结构的运动或应变后，提出了一种理解失效时间的方法。他观察到，当破坏前变形速度的倒数与时间成反比时，观察到一条直线（Saito，1965），称为“Saito线性”。这意味着线性趋势可以外推到速度达到无穷大的一个点，预测故障。最近，其他人注意到滑坡的特征运动模式，称为“三相蠕变”Varnes（1978），其中一个失败的斜坡表现出三个不同的运动周期。最近试图了解控制这种模式的故障机制，已使用失败的斜坡和新的土工试验监测。问题仍然围绕着这个模型的应用，特别是在真实的斜坡的影响，斜坡的几何形状上的演变失败，并解释应变状态从现实世界的监测数据的复杂性。研究提出了观察的影响，在斜坡的几何形状和强度的变化的机制，破坏前的变形，使用一种新开发的技术命名为垂直的“重力加速器”表。在这个模型中，斜坡，形成的材料与弹-脆-塑性性能，在规模上表现为天然斜坡材料，是受到循环加载下降到液压油缸施加快速加速度在同一方向上的重力。因此，使用0.4 m比例尺的模拟物模拟了2，000 m的斜坡。在一系列模型配置中，将测试坡角、坡长、曲率和强度的影响。变形将使用高精度3D结构光扫描仪来监测，该扫描仪测量表面变形。在最后一组实验中，将复制三个仪器齐全的真实山体滑坡中的过程。这些将是Selbourne切割稳定性实验，英国，大田村滑坡，日本，和波斯塞利姆滑坡，马来西亚。使用3D打印将重建每个边坡，模拟破坏并将变形结果与监测数据进行比较，以建立对破坏机制和演化的控制。然后将这些数据与一个新的滑坡运动数据库进行比较，该数据库是从文献中整理出来的，以检验滑坡机制和大量故障中的运动。确定滑坡机制和由此产生的破坏前表面变形的斜坡形状和材料强度的控制，将得到更好的理解观察到的滑坡变形趋势，滑坡触发和运动的机制，并将有影响使用斋藤方法进行边坡破坏预测。