Controlling role of Ta-d pumice on the coseismic landslides triggered by 2018 Hokkaido Eastern Iburi Earthquake
Controlling role of Ta-d pumice on the coseismic landslides triggered by 2018 Hokkaido Eastern Iburi Earthquake
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DOI：
10.1007/s10346-020-01349-y
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发表时间：
2020-01
期刊：
影响因子：
6.7
通讯作者：
Ran Li;Fawu Wang;Shuai Zhang
中科院分区：
文献类型：
--
作者：
Ran Li;Fawu Wang;Shuai Zhang
2018 年北海道胆振东部地震引发了火山碎屑沉积物中的大规模山体滑坡。其中大部分是浅层碎片滑道。根据现场勘察，浅部泥石流进一步分为陡峭平移滑动、平缓平移滑动和V形汇聚滑体动员三种类型。通过纵向剖面、垂直地层剖面和原位硬度试验，对这三类浅层滑坡进行了深入研究。研究发现，这三种类型的浅层滑坡都是从弱Ta-d浮石层的液化破坏开始的，并进一步演化为沿液化滑动带叠加的火山碎屑沉积物的整体流动。为了验证其控制作用并研究弱Ta-d浮石层的剪切行为和抗液化强度，对滑带周围的土体进行了一系列的室内试验（基本物理试验和三轴试验）。试验结果表明，中砂质Ta-d浮石MS和脆性Ta-d浮石CS的抗剪力和抗液化强度均低于其他层位，在强烈地震动下很容易液化。 Ta-d 浮石下方的一层古土壤层渗透性低，导致 Ta-d 浮石风化和水土流失，导致 Ta-d 浮石层中广泛存在脆弱和中砂质浮石层。此外，同震滑坡密度与Ta-d浮石厚度之间的正相关关系从宏观上说明了Ta-d对Iburi滑坡发生的控制作用。
The 2018 Hokkaido Eastern Iburi Earthquake triggered massive landslides in the pyroclastic fall deposits. Most of them are shallow debris slides. Based on the field reconnaissance, the shallow debris slides were further categorized into three types: steep translational sliding, gentle translational sliding, and mobilization of V-shaped convergent sliding masses. The three types of shallow landslides were investigated in depth through longitudinal sections, vertical stratigraphic sections, and in situ hardness tests. All three types of shallow landslides were found to initiate from the liquefied failure of the weak Ta-d pumice layer and further evolve to the overall mobilization of the superimposed pyroclastic fall deposits along the liquefied sliding zone. To testify the controlling role and to study the shear behavior as well as the anti-liquefaction strength of the weak Ta-d pumice layer, a series of laboratory tests (basic physical tests and triaxial tests) were conducted on the soils around the sliding zone. The test results indicate that the medium sandy Ta-d pumice MS and the fragile Ta-d pumice CS have lower shear resistance and anti-liquefaction strength than other layers and they can be easily liquefied under intense ground motion. One paleosol layer underlying the Ta-d pumice shows low permeability and enables weathering and soil erosion of the Ta-d pumice, resulting in the widespread existence of the fragile and medium sandy pumice layers in Ta-d. In addition, the positive relationship between coseismic landslide density and Ta-d pumice thickness demonstrates the controlling role of the Ta-d on Iburi landslide occurrence from a macro perspective.