Model Test Research On The Interaction Between Coral Sand And Pile Under Horizontal Load

When onshore land resources become scarce and the strategy of strengthening the country by the sea becomes imperative,the use of coral sand and other marine sands can be regarded as a way to reduce the marine environment for the construction of marine engineering such as coastal engineering,offshore engineering,and deep-sea engineering.impactful and economical solutions.However,the key issues of offshore infrastructure engineering include studying the mechanical properties and the pile-soil interaction mechanism when horizontal loads such as wind and wave loads act on the pile foundation under different conditions,using coral sand and other sea sand as the foundation soil.In this thesis,an indoor model test device is used,taking rigid piles and coral sand as the research objects,and controlling the three variables of the length of the pile,the particle size of the coral sand,and the distance between the active and passive piles.The method of horizontal grading loading is adopted,the mechanical parameters of the pile body are collected,and the initial displacement image is processed by the particle image velocimetry technology.Using a variety of analysis methods,including pile bending moment distribution curve,coral sand resistance curve,load-pile top displacement curve,pile displacement curve,p-y curve,cloud map and value line map,etc.,the interaction mechanism and law between coral sand and piles under horizontal loads were explored,the results of the experimental study are as follows:Based on the analysis of the single pile model test,under the premise of the density of0.3,as the particle size of the coral sand decreases,the peak value of the soil resistance provided by the coral sand increases,the bending moment of the rigid pile body also increases,and the rotation center of the rigid pile will move upward.When the top of the rigid pile is subjected to a small horizontal load,the coral sand with larger particles can provide greater soil resistance in its shallow layer,that is,the ability to limit the displacement of the top of the pile is enhanced.When the horizontal load is constant,the longer the length of the rigid pile body,the greater the peak value of the pile body bending moment,and the shorter the length of the rigid pile body,the greater the peak value of the soil resistance.Based on the model test analysis of active piles and passive piles,under the premise of a compactness of 0.3,when the active piles move towards the passive piles under horizontal load,as the pile spacing decreases from 3 times the pile diameter to 2 times the pile diameter,both the active pile body bending moment and the soil resistance provided by coral sand increased exponentially,and the increase of both increased with the increase of coral sand particle size.The bending moment of the passive pile increases to a constant value with the decrease of the pile spacing,and the action position of the soil stress of the coral sand between the piles on the passive pile moves upward with the decrease of the pile spacing.When the active pile is moved away from the passive pile under horizontal load,under the condition that the pile spacing is 2 times the pile diameter,the larger the coral sand particles,the greater the disturbance to the passive pile.When the active pile is moved away from the passive pile to 3times the pile diameter,the disturbance degree of the coral sand around the active pile to the passive pile can be ignored.It can be seen from the soil displacement images processed by the image technology of PIV technology that in the single pile model test,the image formed by the movement of the pile body makes the surface coral sand around the pile move in the shape of a spindle.The larger the particle size of the coral sand,the larger the affected area of the coral sand and the slower the decay of the movement speed.In the model test of active pile and passive pile,the larger the coral sand particle size is,the farther the coral sand will spread in the longitudinal direction between the piles,that is,a more obvious soil squeeze effect will be formed.