Study Of Dynamic Characteristics Of Sandy Silt In Western Jilin Province Under Cyclic Loads And Seismic Response Of Embankment Under Poor Geological Condition

Sandy silts containing both sand and silt particles are formed by rock under the action of river scouring and weathering,which result in their poor mechanical properties.These kinds of soil are prone to liquefaction due to their small cohesion and large pore ratio.Due to river scouring and weathering,sandy silts are widely distributed in the middle and lower reaches of rivers.There are many embankments and bank slopes constructed along rivers to ensure the safety of infrastructure in towns.As sanded silts are widely distributed along rivers,they inevitably exist in foundation of these engineering.Embankment foundations are always saturated due to the action of seepage and groundwater immersion.The sandy silts contained in the embankment meet the necessary conditions(saturated)for liquefaction.Therefore,liquefaction failure is easy to occur under the earthquake load,which could leads to various disasters such as landslide and dike burst.In order to explore physical and mechanical properties of sandy silts,study the pore pressure growth law and liquefaction identification method,and reveal the dynamic response and failure mechanism of sandy silts embankment under earthquake load,this paper takes the typical sandy silts in Songhua River Basin of Western Jilin Province as the research object,and takes an embankment in this area as an engineering case to carry out the research of dynamic characteristics of sandy silts in Western Jilin Province under cyclic load and seismic response of embankment with unfavorable geological conditions.The main work and research results of this paper are as follows:(1)Based on the geotechnical test,static and dynamic triaxial test,studied the physical and mechanical properties of sand silts,analyzed the stress-strain characteristics,development rule of pore pressure,stress path development regularity,development rule of dynamic elastic modulus and damping ratio of saturated sandy silts under cyclic load,revealed the failure mechanism of saturated sandy silts under cyclic load.(2)Based on the results of dynamic triaxial tests and deep learning methods,studied the effects of loading times and confining pressure on the critical dynamic stress of sandy silts liquefaction.A back propagation neural network based model of pore pressure growth of saturated silt was established.Based on this model,the liquefaction prediction and safety zone division method of saturated sandy silts were proposed.It was verified that the model has high accuracy and strong generalization ability,and the liquefaction prediction and safety zone division method based on the model are reliable and effective.(3)Taking a sandy silts embankment in the Songhua River Basin in the western part of Jilin Province as an engineering case,the dynamic response of the embankment under seismic load was studied,and the mechanism of liquefaction and the cause of disaster were revealed.