Experimental Study on Liquefaction Characteristics of Threaded Pile Reinforced Aeolian Sand Foundation
Research purposes:With the continuous development of traffic construction in western China,the line project will inevitably cross the aeolian sand valley area,and the roadbed project will face the problem of foundation liquefaction.As a new type of pile foundation emerging in recent years,there are relatively few studies on the mechanical mechanism of pile-soil interaction and anti-liquefaction effect of reinforced liquefiable site under earthquake action.In this paper,the liquefaction characteristics of aeolian sand foundation reinforced by threaded pile are studied for the first time from the perspective of wavelet packet energy variation through shaking table test,and its applicability is verified.The time-frequency-energy evolution law of liquefaction-prone parts of threaded pile composite foundation is further analyzed,and the micro-liquefaction process of aeolian sand is discussed.Research conclusions:(1)Under the action of earthquake,threaded pile can improve the stiffness and overall liquefaction resistance of aeolian sand foundation,and inhibit the change or reorganization of aeolian sand skeleton structure.(2)The variation characteristics of wavelet packet energy are closely related to the liquefaction law of pore pressure response,and it is applicable to evaluate foundation liquefaction.(3)The threaded pile can transfer the liquefaction-prone area of aeolian sand foundation from the middle to the shallow layer,which is conducive to human intervention in foundation liquefaction through foundation reinforcement.(4)When the threaded pile-aeolian sand composite foundation does not liquefy,the vibration response energy is mainly concentrated in the first frequency band(0.1～6.26 Hz).When liquefaction occurs,the energy accumulated at low frequency(2～5 Hz)gradually diverges to high frequency(10～15 Hz),and new energy cusps appear at the time node.(5)At the micro level,the liquefaction process of aeolian sand is an alternating process of shear expansion and shear contraction.The particle arrangement is from close contact to mutual separation,and the thread of the threaded pile body has an inhibitory effect on the volume strain of aeolian sand and reduces its liquefaction potential.(6)The research results can provide some reference for the design of threaded pile reinforcement technology in liquefied foundation.
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