A hybrid investigation of geometrical effects on landslide-tsunamis: Generic hazard assessment and numerical benchmark test cases

建议的研究涉及水体几何形状对滑坡-海啸的影响的调查。为了预测这样的事件，至少可以采用三种方法：(I)物理模型试验，(Ii)数值模拟和(Iii)经验方程。传统的经验公式建立在物理模型试验的基础上。遗憾的是，该模型试验大多是在窄波航道(2D)中进行的，并没有系统地研究水体几何形状的影响。对这种猛烈的自由表面流动的数值模拟直到最近才进入实用阶段。光滑粒子流体动力学SPH是解决这些问题的一种很有前途的计算方法。这项拟议的工作采用了所有这三种方法，使用物理模型测试来验证和改进SPH代码，并开发出迄今为止最通用的经验公式。这项工作直接建立在PI之前通过他的危险评估手册在物理滑坡-海啸建模和真实世界应用方面的成功之上。海啸不仅由地震活动引起，如2011年日本和2004年印度洋海啸灾难，还由其他质量运动引起，如山体滑坡、岩石坠落或冰裂。例如，这种滑坡-海啸(或湖泊或水库中的脉冲波)发生在公元前6100年影响苏格兰的挪威海岸外，1963年造成约2,000人死亡的Vaiont灾难，或1998年在巴布亚新几内亚造成2,100人死亡。在奥地利、加拿大、中国、意大利、挪威、瑞士和土耳其等山区国家，冲击波也经常发生，因此在水库规划阶段需要进行危险评估。英国也经历过类似的情况，例如在苏格兰，它可能受到源自加那利群岛拉帕尔马的潜在滑坡-海啸的影响，在冰川崩塌的背景下，它与航运和石油和天然气行业的相关性越来越大。与地震-海啸相反，在理想条件下，用经验公式可以相对较好地预测滑坡-海啸。然而，这些方程主要是在波浪通道(2D)和波浪盆地(理想3D)中开发的，其中基于2D和理想3D的方程预测的波高因相同的滑动特征而相差一个数量级。目前，人们对由相同的滑动特征产生的2D海啸和理想化3D海啸之间的区别知之甚少。基于2D数据的公式和基于理想化3D数据的公式哪个更适用于特定的原型形状，以及对中间几何形状(例如，大坝侧面的滑动冲击)的一般预测，也根本不清楚。尽管众所周知，在滑坡-海啸(冲击波)预测中，水体几何形状是导致严重低估或高估的原因，但到目前为止还没有系统地讨论水体几何形状的重要影响。拟议的工作将采用(实验-数值)混合方法系统地研究水体几何形状的影响。物理模型实验将在内部波浪水槽和波浪水池中进行，从而消除了显着的尺度效应。独特的测量组合将包括整个滑块运动学、滑块前沿的压力记录和波形特征。这将产生高质量的基准测试案例，对于处理流体-结构相互作用应用和剧烈自由表面流动的数值模型界来说是有价值的。最近发布的功能将通过Blender在SPHyics中包括复杂的几何图形，这将使在2D、理想化的3D和纯数字的中间几何图形中进行额外的测试成为可能。来自这种混合方法的数据集将被用来开发迄今为止最通用的预测滑坡-海啸(脉冲波)的经验公式，从而大大改进对湖泊、水库、峡湾和海洋的预测。

The proposed research concerns the investigation of the effect of the water body geometry on landslide-tsunamis. To predicting such events, at least three approaches may be adopted: (i) physical model testing, (ii) numerical simulations and (iii) empirical equations. Traditionally empirical equations are based on physical model testing. Unfortunately, this model testing has mostly been conducted in narrow wave channels (2D), and did not systematically address the effects of the water body geometry. Numerical simulations of such violent free surface flows have only recently come into practical reach. A promising computational method for solving these problems is Smoothed Particle Hydrodynamics SPH. The proposed work adopts all three methodologies, using physical model testing, to validate and advanced SPH code, and develop the most generic empirical equations to date. The work directly builds upon the PI's previous success in physical landslide-tsunami modelling and real-world applications through his hazard assessment manual.Tsunamis are not only caused by seismic activities such as in the 2011 Japan and 2004 Indian Ocean tsunami catastrophes, but also by other mass movements such as landslides, rock falls or ice calving. Such landslide-tsunamis (or impulse waves in a lake or reservoir) occurred, for instance, off the coast of Norway affecting Scotland in 6100 BC, in the 1963 Vaiont catastrophe with a death toll of about 2,000 or in Papua New Guinea in 1998 with 2,100 fatalities. Impulse waves occur also quite frequently in mountainous countries such as Austria, Canada, China, Italy, Norway, Switzerland and Turkey such that a hazard assessment is required in the planning phase of reservoirs. The UK also experiences similar cases e.g. in Scotland, it may be affected by a potential landslide-tsunami originating at La Palma on the Canary Islands and it is of increased relevance for the shipping and oil and gas industries in the context of ice calving.In contrast to seismic-tsunamis, landslide-tsunamis may be relatively well predicted with empirical equations under idealised conditions. However, these equations were mainly developed in wave channels (2D) and wave basins (idealised 3D) where the wave height predictions with equations based on 2D and idealised 3D differ up to an order of magnitude by identical slide features. At present the differences between 2D and idealised 3D tsunamis generated by identical slide features is poorly understood. It is also not well understood whether formulae based on 2D or idealised 3D data apply better to a specific prototype shape and generic predictions of intermediate geometries (e.g. slide impact at dam flank) are unknown at all. The important effect of the water body geometry was not systematically addressed to date even though it is widely known to be responsible for considerable under- or overestimations in landslide-tsunami (impulse wave) predictions.The proposed work will systematically investigate the effect of the water body geometry with a hybrid (experimental-numerical) approach. The physical model experiments will be conducted in the in-house wave flume and a wave basin thereby excluding significant scale effects. The unique combination of measurements will include the entire slide kinematics, pressure recordings at slide front and wave features. This will result in high quality benchmark test cases valuable for the numerical modelling community dealing with fluid-structure interaction applications and violent free surface flows. The recently released feature to include complex geometries via Blender in SPHysics will make it possible to conduct additional tests in 2D, idealised 3D and intermediate geometries purely numerically. The data set from this hybrid approach will be used to develop the most generic empirical equation to predict landslide-tsunamis (impulse waves) to date resulting in considerably improved predictions in lakes, reservoirs, fiords and the sea.