Layered phenomena and control method of sand pluviation on wide-graded coral soil
Liquefaction of coral soil sites is one of the typical earthquake disaster phenomena in port projects,coastal facilities,and islands.Coral soil has the characteristics of wide gradation,high fine particle content,and easy breakage.The sand pluviation method is an important modeling method for studying saturated site models and unit test liquefaction.In view of the delamination problem that occurs when the sand pluviation method is used to prepare coral soil foundation models,the independently developed large-scale sand pluviation device,high-speed camera and PFC3D discrete element numerical simulation are used.By simulation,the effects of fine particle content,flow rate,drop distance and moving speed of sand outlet on layered phenomena were analyzed.The generation mechanism of the layered phenomena was revealed,and corresponding control methods were established.The test results show that compared to the drop distance and the moving speed of the sand outlet,the fine particle content and flow rate are the main factors affecting layered phenomena.As the fine particle content increases,the layered phenomena gradually weakens.As the flow rate increases,the layered phenomena gradually becomes obvious.When the drop distance and the moving speed of the sand outlet reach a certain range,the layered phenomena will no longer increase,and the changes were not obvious.High-speed camera analysis shows that the separation of coarse and fine particles occurs when the coarse and fine particles move at the sand outlet,and there is an obvious separation boundary.The results show that the layered phenomena is caused by gravity,air drag force,and the lateral movement of the sand outlet.The PFC3D discrete element was used to simulate the process of sand pluviation molding.The simulation results were highly consistent with the results of photos taken by high-speed cameras,which proved the feasibility of the PFC3D numerical simulation method.Finally,combined with influencing factors such as flow rate,falling distance,and sand outlet moving speed,a method that can effectively control the layered phenomena of sand pluviation is proposed to provide guidance for the preparation of large-scale wide-gradation coral soil models.
NETL
NSTL
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