Stability Analysis Of Sea-bed Slope Around Artificial Island Offshore Caofeidian

Caofeidian Island is located in the east of Hebei Province,the center of the Bohai Rim.It is an important port for import and export of goods in the Northeast and North China and the core of the National Coastal Strategy of Hebei Province.Current data of water depth,substrate,suspended sand and the tide are from the field survey in 2015.The distribution characteristics and changes of various indicators before and after the construction of the artificial island are analyzed by the long-term monitoring of Caofeidian.The evaluation partition of submarine topography and geomorphology stability is obtained by assigning value to factors that affect the stability of the seafloor.The safety factor of the seabed profile using GEO-SLOPE is calculating and obtained to investigate the possibility of landslides in Caofeidian Region.Through the above research,the characteristics of Caofeidian's submarine slope are obtained and summarized as follows:(1)As for the characteristics of tides,there is no large change in the tidal current field after sea reclamation,only the tidal current field have partly undergone significant changes;As for the characteristics of the seabed sediment,there is a trend of refinement on both sides of the east and west of Caofeidian,but Caofeidian Front sea area is stable.As for the water depth change characteristic,Caofeidian Front sea area shows erosion;the west side of Caofeidian area shows siltation;the east side shows washout and siltation.As for the wave characteristic,the effect of water depth on the wave is relatively large.the wave height is large in open sea area,whilearound the cofferdam project and the sand island area,the wave height decreases due to obstruction.(2)Most areas in the Caofeidian sea area show good geomorphological stability.The areas near the coast have better stability,mainly locating in the inner harbor,the beach on the east side of Caofeidian Front,and the northern side of Dragon Island.The areas with moderate stability are distributed in tidal creeks,mainly locating in Laolonggou,deep sea troughs of Bohai and the Nanpu.The areas with poor stability are rarely distributed,less than 1%of the study area,mainly lcocating at the southwestern of Dragon Island,end of the breakwater,and a small block at the southeast side of Caofeidian Front.(3)For the Landslide stability for slopes in the study area,under the daily operating conditions,the stability of the landslide in the seabed of Caofeidian area is good with a large safety reserve.The most dangerous area of the seabed slope in the Caofeidian area is located near the 50,000-ton bulk cargo terminal.Analysis of No.3 Profile revealed that in the event of failure,the plastic yield zone of the entire model was mainly within the 200m-400m off-shore bank(the steepest in the study area),and it affected shallow soil layers.According to the study on the influencing factors of slope stability,the slope is a main influencing factor of the slope stability.The influence of the wave load has less effect on the slope stability.The influence of submarine slope topography on stability is greatly reduced under the earthquake loads.