Dynamic Characteristics Research And Seismic Compression Calculation Of Organic Matter-disseminated Sand

With the implementation of the major strategy of the Hainan International Free Trade Port in Hainan,various large-scale projects have been constructed in the port area,especially the integration and optimization of port construction.The force situation of Hainan Island offshore foundation structures is more complex,in addition to bear the weight of the building itself,but also by cyclic loading waves,earthquakes.There are differences in the dynamic deformation and damage of the building structure and the foundation.Therefore,this paper mainly studies the dynamic characteristics,cumulative deformation and seismic subsidence characteristics of the Hainan organic matter disseminated sand foundation under the action of seismic loads,and provides reference value for actual engineering construction and theoretical research.The main research results of the thesis have the following three parts:(1)Calculating and analyzing the dynamic triaxial test data,we can discuss the changes between the dynamic modulus and dynamic damping ratio of organic matter disseminated sand under different influencing factors(vibration load,natural moisture content,consolidation ratio,confining pressure and waveform)and dynamic strain.Through the analysis of the development trend of the two curves,the dynamic modulus function and the dynamic damping ratio function are established,which more intuitively reflect the changing discipline of the dynamic parameters with the dynamic strain,and the Hefei expansive soil is used to be verified.(2)The relationship between dynamic strain and vibration frequency of organic matter disseminated sand under different vibration loads,natural moisture content and consolidation ratio are studied through indoor dynamic triaxial tests.Based on the relationship curve between dynamic strain and vibration frequency,the concept of stiffness softening is introduced,the dynamic strain is converted into a softening index,and a stiffness softening model is established.The model parameter d is used as an index to evaluate the attenuation characteristics of the soil.(3)In-depth study and analysis of the calculation method of soil subsidence,while expounding the advantages and disadvantages of the numerical calculation method of soil subsidence and the empirical model of seismic subsidence.Based on previous research results and calculation methods,this paper adopts the pseudo-static method to establish the seismic subsidence model of organic matter disseminated sand,transforms the model equation,and uses εd/σult～εd and Lg(εd)～Lgt relationship curve to determine the parameter values of the seismic subsidence model of organic matter disseminated sand.