Experimental Research On Dynamic Characteristics Of Soft Foundation Of Tangshan Offshore Wind Farms

Taking the offshore wind power project in Tangshan coastal area as the research background,aiming at the cyclic load generated by the soil around the pile foundation under the action of wave load,the dynamic characteristics of the soil around the pile foundation are studied.The dynamic three-axis test was carried out to analyze the dynamic elastic modulus,dynamic strength and dynamic damping ratio of Tangshan coastal soft soil under different loading frequency,confining pressure and dry density.In order to further study the initial dynamic parameters of coastal soft soil in Tangshan area.The research contents and achievements of this paper are divided into the following aspects:First of all,Based on the geological survey report and the field sampling of soft soil foundation in the field,the test was carried out to study the macro mechanical properties of the soil.In addition,scanning electron microscopy(SEM),energy chromatography analysis(EDS),X ray diffraction(XRD)microscopic characterization testing techniques were used to reveal the intrinsic relationship between microstructure and macro mechanical properties of soil.Secondly,based on the DDS-70 dynamic triaxial test system,the dynamic characteristics of coastal soft soil under cyclic loading are studied.According to the variation law of soil dynamic strength parameters in the field,the range of critical dynamic stress ratio of soft soil in the field is clarified.Based on the analysis of the experimental data,the influence of the dynamic elastic modulus and the dynamic variable amplitude of the dynamic damping is evaluated,and the dynamic response characteristics of the coastal soft soil in Tangshan area are summarized.Then,the dynamic elastic modulus and dynamic damping ratio of coastal soft soil under different loading frequency,confining pressure and dry density are studied.The results show that the trend of cumulative dynamic strain of coastal soft soil follows the Monismith index model.The trend of the modulus characteristic is in accordance with the hyperbolic variation.Based on the calculation and analysis of the experimental data,the maximum dynamic elastic modulus Edmax and the maximum dynamic shear modulus Gdmax of the soil under different test conditions are clarified.Finally,through the experimental study of this system and summarizes the characteristics of the dynamic response of offshore wind farms in Tangshan coastal soft foundation;applied to dynamic characteristic parameters of foundation soil of the project,provide the basis for pile foundation seismic design,seismic isolation,seismic design.