Regional variability of slope stability: application to the Eel margin, California
Regional variability of slope stability: application to the Eel margin, California
复制标题
边坡稳定性的区域变异：应用于加利福尼亚州 Eel 边缘
DOI：
10.1016/s0025-3227(98)00120-0
复制
发表时间：
1999
期刊：
影响因子：
--
通讯作者：
F. Wong
中科院分区：
文献类型：
--
作者：
Homa J. Lee;J. Locat;P. Dartnell;Kenneth Israel;F. Wong
海底斜坡失稳的位置取决于斜坡驱动力和沉积阻力的相对大小。这两种情况因区域而异，当数据在地理信息系统中组织时，其影响可以得到解决。研究区域的大陆边缘附近的鳗鱼河提供了一个很好的机会，应用地理信息系统空间分析技术的斜坡稳定性评价。在这一区域，条带测深图详细显示了海底形态和坡度分布，对70多个箱式岩芯的沉积物分析描绘了海底表面附近沉积物密度的变化。根据海底研究区的十项岩土工程研究结果，我们开发了一种算法，将表层沉积物密度与地震产生的循环荷载类型的抗剪强度相关联。强度和应力标准化程序提供的结果，在概念上是独立的浅地层深度。如果沉积物岩性没有显著变化，并且可以估计固结状态，则深度的结果是严格适用的。否则，该方法仅适用于浅层边坡破坏。区域密度，坡度和预期的地震震动信息的水平相结合，在GIS框架中产生的地图，说明了相对稳定的斜坡在面对地震引起的故障。当将预测的相对斜坡稳定性的测量结果覆盖在条带测深的斜视图上时，在沿倾伏背斜以北的中斜坡区域沿着的其他平滑斜坡上观察到该斜坡稳定性的变化。包含分散的麻点冲沟的斜坡部分的稳定性低于包含具有较尖锐边界和较陡侧面的冲沟的单独部分。这种关联表明，我们的边坡稳定性分析涉及到稳定的冲沟两侧。研究区的其余部分显示出很少有明显的迹象表明，除了一个功能，已成为众所周知的“洪堡幻灯片”，但它是太深的，是服从斜坡稳定性预测技术在此提出。在一般情况下，很少有边坡故障已被映射在鳗鱼利润研究领域，尽管高水平的地震活动，沉积物积累的相对较高的速度，以及其他人观察到的气体充电的程度。
Relative values of downslope driving forces and sediment resisting forces determine the locations of submarine slope failures. Both of these vary regionally, and their impact can be addressed when the data are organized in a Geographic Information System (GIS). The study area on the continental margin near the Eel River provides an excellent opportunity to apply GIS spatial analysis techniques for evaluation of slope stability. In this area, swath bathymetric mapping shows seafloor morphology and distribution of slope steepness in fine detail, and sediment analysis of over 70 box cores delineates the variability of sediment density near the seafloor surface. Based on the results of ten geotechnical studies of submarine study areas, we developed an algorithm that relates surface sediment density to the shear strength appropriate to the type of cyclic loading produced by an earthquake. Strength and stress normalization procedures provide results that are conceptually independent of subbottom depth. Results at depth are rigorously applicable if sediment lithology does not vary significantly and consolidation state can be estimated. Otherwise, the method applies only to shallow-seated slope failure. Regional density, slope, and level of anticipated seismic shaking information were combined in a GIS framework to yield a map that illustrates the relative stability of slopes in the face of seismically induced failure. When a measure of predicted relative slope stability is draped on an oblique view of swath bathymetry, a variation in this slope stability is observed on an otherwise smooth slope along the mid-slope region north of a plunging anticline. The section of slope containing diffuse, pockmarked gullies has a lower measure of stability than a separate section containing gullies that have sharper boundaries and somewhat steeper sides. Such an association suggests that our slope-stability analysis relates to the stability of the gully sides. The remainder of the study area shows few obvious indications of slope instability except for a feature that has become known as the `Humboldt Slide,' but it is too deep-seated to be amenable to the slope-stability-prediction techniques presented herein. In general, few slope failures have been mapped in the Eel margin study area despite the high level of seismicity, the relatively high rates of sediment accumulation, and the extent of gas charging observed by others.