【摘要】 随着海洋工程的发展,海底滑坡作为一种潜在的地质灾害逐渐成为人们关注的热点.本文采用二维极限平衡法计算并分析了海底斜坡稳定性问题.通过对斜坡模型在各种条件下安全系数的计算,定量分析了斜坡内在因素(如斜坡角度、主要土力学参数)和主要触发机制(地震、快速堆积等)对安全系数的影响.理论计算表明,静态条件下,均质斜坡角度小于20°时,均处于稳定状态;对于含软弱层的斜坡,快速堆积等引起的不排水状态下斜坡安全系数明显降低,斜坡角度大于14°时就会发生失稳.拟静态条件下,当地震动峰值加速度(PGA)小于0.15g时,对于角度小于20°的均质斜坡处于稳定状态,但PGA大于0.25g时,角度大于13°的斜坡即处于失稳状态;对于含软弱层斜坡,PGA为0.1g时,角度大于10°的斜坡即处于不稳定状态;当PGA大于0.3g时,3°以上的海底斜坡即处于失稳状态,发生海底滑坡.结合南海北部陆坡海底地形、地貌特征,在静态条件下,均处于稳定状态;但在地震加载的拟静态下,根据南海北部地震动峰值加速度分布,台湾浅滩段则处于不稳定状态.这解释了该区域大陆坡折带处海底滑坡广泛发育的原因,也表明了地震是引发南海北部滑坡最主要的触发机制之一.更多还原

【Abstract】 With the development of ocean engineering,submarine landslide becomes a focus topic for its potential harmfulness.In this paper,the stability of submarine slope in the northern South China Sea is analyzed using 2D limit equilibrium method.Based on calculation of safety factors under various conditions,the influence of slope internal factors(such as slope angle,the main parameters of soil mechanics) and main trigger mechanisms(earthquakes,rapid accumulation,etc.) on safety factor is analyzed quantitatively.Theoretical calculations show that,homogeneous submarine slopes with angle less than 20° are stable under static conditions.For submarine slopes with a weak layer,excess pore pressure generated by rapid accumulation can significantly reduce safety factor,which causes the slope instability with an angle greater than 14°.Under pseudostatic conditions,when the earthquake peak ground acceleration(PGA) is less than 0.15 g,the homogeneous slope with the angle less than 20° is stable.However,with the PGA greater than 0.25 g,the slopes with angle greater than 13° are in unstable state;For case of having a weak layer,when PGA=0.1 g,the slope with angle greater than 10° will be in an unstable state;when the PGA≥0.3 g,the submarine slopes with angle greater 3° will be instability.Combining with the topography,geomorphology characteristic,the northern slope of the South China Sea are stable under static conditions.However,in the case of earthquake loading,the Taiwan Bank section will be unstable,according to the distribution of PGA on the northern slope of the South China Sea.This is a reason for submarine landslides developed extensively in this area.In addition,results show that earthquake is one of the most important trigger mechanisms in the northern slope of the South China Sea.更多还原