CAJ | 학술논문

建立现浇 X 形桩(XCC 桩)桩-土体系三维有限元模型，对 XCC 桩低应变检测动力响应进行数值模拟，得到完整桩和缺陷桩的桩顶速度响应结果，并分析完整桩及缺陷 XCC 桩桩顶速度响应特性及规律。计算结果表明：XCC 桩低应变瞬态动测时桩顶速度响应存在明显的三维效应，桩心(激振点)附近点的入射波峰值较大，且到达时间较早；距离桩心越远点的入射波峰到达时间越滞后，入射波峰值从桩心到尖角边界先减小后增大。桩顶距桩心距离相同的环向上各点的入射波和反射波区别不大，而各点所受的高频干扰情况并不相同。变模量桩的入射波和完整桩相同，反射波峰值较完整桩小，反射波峰对应时间较完整桩滞后。局部缺陷桩桩顶距桩心距离相同环向各点的第一个缺陷反射波有微小差别，而第二个缺陷反射波有较大差别。
건립현요 X 형장(XCC 장)장-토체계삼유유한원모형，대 XCC 장저응변검측동력향응진행수치모의，득도완정장화결함장적장정속도향응결과，병분석완정장급결함 XCC 장장정속도향응특성급규률。계산결과표명：XCC 장저응변순태동측시장정속도향응존재명현적삼유효응，장심(격진점)부근점적입사파봉치교대，차도체시간교조；거리장심월원점적입사파봉도체시간월체후，입사파봉치종장심도첨각변계선감소후증대。장정거장심거리상동적배향상각점적입사파화반사파구별불대，이각점소수적고빈간우정황병불상동。변모량장적입사파화완정장상동，반사파봉치교완정장소，반사파봉대응시간교완정장체후。국부결함장장정거장심거리상동배향각점적제일개결함반사파유미소차별，이제이개결함반사파유교대차별。
A three dimensional finite model of an X-section cast-in-place concrete pile-soil system is established to simulate wave propagation in a low strain integrity X-section cast-in-place concrete pile (XCC pile).Velocity responses in the time domain at the top of the intact and defective piles are obtained.The velocity response characteristics of the intact pile are analyzed in addition to the velocity response curves of the defective piles.The results reveal that the velocity response at the top of the XCC pile during low strain integrity testing shows serious 3D effects,resulting in the peak value of the incident wave close to the pile center being largest,and the arrival time of the peak value of the incident wave close to the pile center being earliest.The farther a point is from the pile center,the more hysteretic is the peak of the arriving incident wave.The peak value of the incident waves first increases and then reduces from the pile center to the pile boundary.The inci-dent and reflected waves at different points along the ring direction at the top of the intact pile are very similar,but the disturbing waves of different points are not the same.The arrival time of the incident waves in the pile with variable modulus are the same as those in the intact pile,but the arrival time of the peak of the reflection wave at the bottom of the pile with variable modulus is later than that in the intact pile,and the peak value is smaller.The first defective reflected waves at different points along ring direction at the top of the defective XCC pile shows little differ-ences,but the second one shows larger differences.