珠江口盆地海底滑坡发育特征及成因机制

Development characteristics and cause mechanism of the submarine landslides in Zhujiang River Mouth basin

海底滑坡属于海洋地质灾害的一种主要类型。国内外海洋领域学者对不同地理位置的海底滑坡做过一些建设性的研究工作,国内学者在南海北部海底滑坡的研究中主要关注的是灾害分区和成因分析,而对南海北部珠江口盆地海底滑坡的形态、类型、规模、分布特征等方面的基础性工作还缺乏系统的科学分析。通过2012年以来对珠江口盆地滑坡区海洋土的静力触探试验、十字板剪切试验及室内分析试验,揭示出珠江口盆地海洋土的垂直分布特征,根据不同深度海洋土的工程性质差异可将该区土体自上而下划分为5层。按照海底滑坡所处的地貌单元不同,把珠江口盆地水深160~1280 m范围内发育的滑坡分为4处规模较大的滑坡带,均呈NE-NEE向展布,主要为顺层型滑坡、圆弧型滑坡和崩塌型滑坡3种基本类型,规模从4 km2到800 km2不等,集中分布在北纬19°-22°,东经113°-117°范围内。通过海底地质环境、水文气象环境及力学平衡分析,指出了影响海底滑坡稳定性的主要因素包括地震活动、海流影响及沉积物质的快速堆积3个方面。

Submarine landslide belongs to a main type of marine geological disaster.Domestic and overseas scholars have made some constructive works on the submarine landslide in different locations.Domestic scholars focused on the study of disaster partition and cause analysis in the north of the South China Sea.However,the basic work of the shape,type,size,distribution characteristics about submarine landslide is lack of scientific analysis in the Zhujiang River Mouth basin in the South China Sea.Through the cone penetration test,vane shear test and laboratory analysis test in the marine soil in 2012,this paper has revealed the vertical distribution characteristics of the soil.The marine soil can be divided into 5 layers by the different properties of different depths from top to bottom.According to different units in submarine geomorphic locations,the landslide has been divided into 4 large zones.The distribution of landslide zones is NE-NEE,and the types of landslides are bedding landslide,circular arc landslides and collapse landslides,and the size range is from 4 km2 to 800 km2.They are located in 19°-22°N,113°-117°E.Through meteorological,hydrological environment and mechanical equilibrium analysis,the article has pointed out the main factors influencing the stability of submarine landslides are the seismic activity,currents and sediment quality rapid accumulation.