Reaserch On The Characteristics Of Marine Engineering Geology And The Depth Of Pile Penetration In Caofeidian Shoal

Caofeidian Shoal is a part of the ancient Luan River Delta which was formed in the mid-Holocene. After Luan River estuary shifting eastward, the sediment source was cut off. The loose surface sediments in the region was reformed by the wave and the tidal factors and formed a barrier island lagoon system. From west to east it zonally distributed Caofeidian, Yaotuo, Caomutuo, Hatuo and other bars. Sstudy area is the Jidong Oilfield's main offshore oil and gas exploration block. The topography and ocean dynamic environment is complex in this area.Therefore, by studying the shoal's characteristics and laws it can reduce the impact on marine production.According to its different dynamic sediment environment, the study area can be further divided into three parts: the in-barrier tidal flat areas,the out-barrier shallow water areas and the large-scale tidal channel.The surficial sediments in study area is divided into fine sand and silt area, clay silt area, silty clay (mud) area. Fine sand and silt is dense, silt and mud silt is relatively soft.According to the drilling and shallow stratigraphic section information, the strata can be is divided into 8 layers within 40 m, top-down followed by: sandy muddy silt, sandy silt, sandy muddy silt, silty sand, sandy muddy silt, muddy silt, silty sand. And the⑥layer's top interface can divide the strata into two parts according to l4C dating information: over the interface the age <1 million years (3280±70 and 8840±250 a.), below the interface the age> 1 million years (10850±100 And ll230±150 a.).The②layer sandy silt is thick, stable in horizontal, dense and the large area exposed to the sea bottom and have a great impact on the marine drilling platform penetrating depth. By analyzing the physical and mechanical property of the silt ,we make an adjustment of the mechanical parameters in applying the formula of Terzaghi ultimate bearing capacity of foundation .The calculated depth we got is in accords with the practical penetration depth well. This method can also be used in solving the similar problem later.