Research On Engineering Properties Of Submarine Soil In The Yellow River Estuary Based On Seabed Cone Penetration Test

Nowadays,with the increase in marine exploration and development,there are more and more investigations on marine research and offshore engineering facilities.Whether to carry out marine engineering geological survey or submarine geological hazards evaluation,the parameters of submarine soil on physics and mechanics are essential to obtain.Cone Penetration Test(CPT)is one of the in-situ testing methods,so it has many advantages compared to the traditional drilling-sample analysis method.CPT technology brings about less disturbance to soil,and it's efficient,accurate and continuous.Additionally,the CPT testing data can reflect the initial stress-strain status of soil.In view of those advantages,CPT is increasingly being applied to the marine engineering geological survey and investigation of geotechnical properties.It is an important means to quantitatively evaluate the geological conditions of the survey area and investigate the geological hazards of the seabed.In this paper,the study area will be selected in the waters of the Yellow River underwater island,and the main oil production block in Sinopec Shengli Oilfield is located in the sea area.The number of offshore platforms is large and the submarine pipeline is close,but the submarine engineering geological conditions are extremely complicated and the marine geological disasters are frequent.Therefore,it is of great significance to study the applicability of seabed Cone Penetration Test in the sea area and the accumulation of regional experience to explore the application of static cone penetration technology in complex stratigraphic structure.According to the application of static cone penetration test in the Bohai Sea area engineering survey,this paper introduces the synopsis of the study area,the development process of the static CPT equipment,the composition and testing method of the seabed cone penetration test system.The test data is corrected and sorted out,besides,it is compared with the drilling data to comprehensively analysis some issue.The results of the study are as follows:1.Introduce the composition of the equipment and testing method about the heavy seabed static cone penetration test system-ROSON100,analyze the main factors that influence the accuracy of the test.2.According to the measured parameters of static cone penetration test data,the CPT curve is drawn,the type of soil is determined,the strata are divided,the hard soil layer and the shells are analyzed comprehensively by combining with the drilling histogram.Compared with the geological drilling data,the accuracy of stratum division by means of CPT is evaluated quantitatively.3.The correlation analysis about the Cone Penetration Test parameters and the physics-mechanics parameters of the silty clay obtained by the indoor experiment is carried out,and this paper generalize the regression equations which are suitable for the study area,afterwards the regional experience is accumulated.4.According to the cone resistance(qc),one of the CPT parameters,this paper estimates the undrained shear strength of the cohesive soils.Comparing the results with the UU Triaxial test and laboratory direct shear test data,we determine the empirical parameter(Nkt)that applies to the study area.5.The liquefaction identification method based on the cone penetration test data is used to judge the liquefaction potential of surface silt and silty sand in the study area.It is concluded that when the seismic fortification intensity is 7 degrees and 8degrees,the silt and silty sand within the depth of 15 meters under the seabed will not be liquefied.This is consistent with the results of liquefaction evaluation based on standard penetration test and dynamic triaxial test.When the seismic fortification intensity is 9 degrees,the silt layer and silty sand layer within the depth of 15 meters under the seabed will be liquefied.