In the last 22 years, four large (between approximately 1000 and 5000 m³) flowslides in anthropogenic fill materials have occurred in residential areas of the greater Wellington region, New Zealand. Such failures are relatively rare, given that there are over 1600 mapped fill bodies, formed between the early 1900s and present day within the region. Nonetheless, their performance under strong earthquake shaking has yet to be tested, given no strong ground motions (>0.15 g) have shaken the region since their construction. In this study, we used remote sensing techniques, borehole investigations, geotechnical testing and numerical modelling to investigate two fill bodies that are characteristic of those constructed across the Wellington region. This paper presents the results from the dynamic analysis of these two sites under strong earthquake shaking.

The maximum anthropogenic fill thicknesses at both sites ranged between 20 m and 30 m. The fills tested varied from sandy gravel with some silt to clayey gravelly silt sand (D50 from 0.02 mm to 10 mm and D90 from 5 mm to 50 mm). Based on the field mapping, site investigation and laboratory results, two-dimensional geotechnical cross-sections of the sites were generated and used as the basis for the numerical simulations. Accelerograms recorded from eleven local and overseas earthquakes were used as inputs for the modelling. These were selected and scaled to simulate the amplitude and frequency content of the different types of earthquake shaking that could affect the sites up to 2.5 g, which represents a peak ground acceleration with an approximate annual exceedance probability of 0.00005. The results indicate simulated permanent ground displacements, due to sliding of the fill in the range of 0.01 m to >10 m, with the amount of displacement increasing with increasing Peak Ground Acceleration (PGA). Although at small displacements it is unlikely the fill slopes would fail catastrophically to form flowslides, the simulated permanent displacements are large enough for an earthquake with a free field PGA of >0.6 g (annual exceedance probability (AEP) of 0.002) to potentially disrupt buried elastic pipe utilities (especially the water pipes). Such deformation could lead to the leakage of water from broken pipes, and an increase in pore-water pressure within the fills, which could in turn lead to the development of post-earthquake flowslides. After a major earthquake, such cascading hazards may pose a major problem for recovery activities.

在过去的22年中，有4个大型项目（约1000至5000 m ³人为填充材料中发生的流滑发生在新西兰大惠灵顿地区的居民区。鉴于该地区1900年代初至今天之间形成了1600多个映射的填充体，因此此类失败相对罕见。但是，由于自建造以来没有强烈的地面震动（> 0.15 g）震动过该区域，因此其性能尚待测试。在这项研究中，我们使用了遥感技术，钻孔研究，岩土工程测试和数值模型来研究两个填充物，它们是惠灵顿地区构造的填充物的特征。本文介绍了这两个地点在强震下的动力分析结果。

两个地点的最大人为填充厚度为20 m至30 m。测试的填充物从含一些粉砂的砂砾到黏性砂砾粉砂（D50为0.02 mm至10 mm，D90为5 mm至50 mm）。根据现场测绘，现场调查和实验室结果，生成了现场的二维岩土横截面，并将其用作数值模拟的基础。从11次本地和海外地震中记录的加速度图被用作建模的输入。对这些地震波进行了选择和缩放，以模拟不同类型的地震波的振幅和频率含量，这些震荡波可能影响到2.5 g以下的地点，这代表着地面加速度峰值，每年的超出概率为0.00005。结果表明，由于填充物在0.01 m至> 10 m范围内滑动，模拟的永久性地面位移，位移量随峰值地面加速度（PGA）的增加而增加。尽管在小位移情况下，填方坡度不可能灾难性地形成滑坡，但模拟的永久位移足够大，足以使自由场PGA> 0.6 g（年超出概率（AEP）为0.002）的地震有可能破坏埋藏物弹性管道工具（尤其是水管）。这种变形可能导致水从破裂的管道漏出，并且填充物中的孔隙水压力增加，这又可能导致地震后流动滑坡的发展。大地震过后