南海北部陆坡表层沉积物强度特征研究

SURFACE SEDIMENT STRENGTH IN BED-SLOPE OF NORTHERN SOUTH CHINA SEA

随着海洋开发活动由浅海走向深海，南海北部陆坡的沉积物强度特性逐渐成为关注热点。本文通过参与2015年与2016年共享航次计划，在南海北部莺琼陆坡、神狐陆坡、东沙陆坡、台湾浅滩陆坡进行沉积物重力取样与箱式取样，并现场剖样，用以进行沉积物强度测试。地质取样结果表明东沙陆坡砂含量相对较高并发现直径约22cm黑色气孔状碳酸盐结核。在神狐陆坡沉积物表层发现活体壳类生物，在110cm深度处发现壳类生物遗骸。十字板剪切试验与笔式贯入试验结果表明南海北部陆坡，沉积物强度差异较大。但总体而言，除东沙陆坡外，莺琼陆坡、神狐陆坡、台湾浅滩陆坡表层沉积物强度一般较低。0～20cm范围内，笔式贯入阻力一般小于0.1N，十字板剪切强度最大一般不超过10kPa。0～300cm深度范围内，沉积物强度沿深度方向大致呈递增趋势，个别站位递增趋势不明显。台湾浅滩陆坡等南海北部陆坡表层沉积物存在强度分层：分层界面以上，沉积物强度较低；分层界面处，沉积物强度骤增。该分层界面可能是海底滑坡的潜在滑动面。

With the rapid development of marine exploitation activities, the sediment strength in the bed slope of Northern South China Sea has attracted more and more attention. The vane shear tests and penetration tests are conducted on ship with the sediment samples collected by gravity corer and box corer in the Yingqiong Slope, Shenhu Slope, Dongsha Slope and Taiwan Slope. Sampling results show that the sediments in Dongsha Slope are sandy and the carbonate nodules with the diameter of 22cm are found. Besides, living bivalve is found on the seabed and the organic remains are found 110cm below the seabed in the Shenhu area. The sediment strength results show that the penetration resistance is less than 0.1N and the vane test strength is no more than 10kPa within 20cm below the seabed. Generally, the sediment strength increases with the depth below the seabed. Furthermore, sediment strength stratification is found within 200cm below the seabed, especially in the Taiwan Slope. The sediment strength is low above the interface and increases sharply under the interface. The sediment strength interface is the potential sliding surface.