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阿尔及利亚边缘是一个地震活动很活跃的地区,上个世纪以来,发生了多个高震级的地震。本研究用数值模拟的方法把岩土工程技术和沉积学的数据结合起来,量化评价当今阿尔及利亚边缘的斜坡稳定性问题。动三轴液化试验、固结试验和十字板剪切试验等土力学试验,被运用在研究区收集来的沉积岩芯上。结果显示,对于2003年5月21日MW=6.8级的布米尔达斯地震,理论评估在距离震中30km开外的沉积柱仍具有发生液化的潜能。正如对钻孔岩芯中沉积物的描述那样,我们指出薄层的粉砂质岩层是导致沉积岩在地震中变形和发生液化的主要原因。数值计算表明,斜坡破坏可能发生在地震的峰值地面加速度(PGA)超过0.1g时,并且当地震的峰值地面加速度低于0.2g时,浅层的粉砂质沉积物可能会引发砂土液化。另外,把预测的斜坡破坏和海底地形图观测出的破坏迹象作比较可以得出,地震和随后的大量位移能够解释如今这个区域的地形形成过程。
The edge of Algeria is a region where seismic activity is very active. Since the last century, several high-magnitude earthquakes have taken place. In this study, the geotechnical engineering and sedimentology data were combined by numerical simulation to quantitatively evaluate the slope stability problems on the edge of Algeria nowadays. Soil mechanics tests such as dynamic triaxial liquefaction test, consolidation test and cross-shear test are applied to sedimentary cores collected from the study area. The results show that for the MW = 6.8 class of the Mayr Mudas earthquake on May 21, 2003, it is theoretically estimated that sedimentary columns that are 30 km away from the epicenter still have the potential to liquefy. As the description of sediment in boreholes, we point out that the thin layer of siltstone is the major cause of sedimentary deformation and liquefaction in the earthquake. Numerical calculations show that slope failure may occur when the PGA of the earthquake exceeds 0.1 g and shallow sediments may initiate sand liquefaction when the peak ground acceleration of the earthquake is less than 0.2 g. In addition, comparing the predicted slope damage to the sign of damage observed on the seafloor topographic map, it can be concluded that earthquakes and the subsequent mass displacement explain today’s terrain formation.