黄河三角洲沉积体的工程不稳定性

ENGINEERING INSTABILITY OF THE DEPOSITION BODIES IN THE YELLOW RIVER DELTA

对多年来黄河三角洲的调查资料分析表明 ,三角洲的不稳定性比较突出 ,对海洋工程设施危害极大 ,主要表现在以下几个方面 :1工程软弱层是三角洲不稳定的根本因素 ,是形成海底刺穿、大型海底滑坡等灾害体的基础 ,尤其是极端条件下触发软弱层流动 ,所产生的大型海底滑坡带来的灾害是巨大的 ;2水下斜坡是三角洲上主要的工程不稳定区 ;3海底冲刷和年内的动力调整在海底形成的活动层对海底铺设的管线和海岸大坝构成危害 ;4应高度重视三角洲下沉产生的工程危害 ,造成三角洲整体下沉的主要因素是构造、均衡、压实下沉和海平面上升 ,这些因素耦合下沉量比较大 ,估计未来 10 a将下沉 80 cm,大大降低了已有工程设施的设计标准 ,同时 ,将陆地测量基准系统破坏。

Deltas are the important parts in the coastal zone.The geological change and hazard in the delta area is closely related with the human activity.Based on the analysis of the measurement data in the Yellow River delta,the result shows that the delta instability is very grave and its harm to the engineering buildings is large.These harms are the following:(1)The engineering soft stratum is the fundamental factor that results in the delta instability.It is the cause to form the diapirisim and landslide in seabed.Under extreme condition (quake,storm),the soft stratum is triggered and moves.Meanwhile,the large scale seabed landslide is formed.(2)The delta subaqueous front slope is the major area of engineering instability.(3)The marine erosion and the active stratum of the seabed due to the dynamic adjustment are harm to the oil tube in seabed and the dams along the coastal line.(4)The delta subsidence value due to geologic tectonics,gravity equilibrium,sediment compression and sea level rising will access 80 cm in 10 years.It causes the design standard of the project establishment to be reduced and the geodesic datum plane system to be destroyed.