基于频谱分析的饱和砂土场地直斜群桩承台--土体耦合作用下桩身弯矩分布规律研究  

Study on the distribution law of the bending moment of vertical and batter piles in saturated sand under cap and soil coupling based on frequency analysis

作　　者：张健 李雨润 闫志晓[1] 戎贤 ZHANG Jian;LI Yurun;YAN Zhixiao;RONG Xian(School of Civil and Transportation Engineering,Hebei University of Technology,Tianjin 300401,China;Civil EngineeringTechnology Research Center of Hebei Province,Hebei University of Technology,Tianjin 300401,China)

机构地区：[1]河北工业大学土木与交通学院,天津300401 [2]河北工业大学河北省土木工程技术研究中心,天津300401

出　　处：《岩石力学与工程学报》2020年第4期829-844,共16页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(51778207);河北省自然科学基金资助项目(E2018202107);河北省研究生创新能力培养计划(CXZZBS2019041)。

摘　　要：地震荷载作用下,群桩结构受到承台和土体共同作用,不同桩型的桩身弯矩会发生明显变化,尤其在饱和砂土条件下。因此,为研究上述问题,利用浙江大学ZJU400土工离心机进行饱和砂土场地直斜群桩地震动力响应试验,并通过频谱分析的方法,对饱和砂土场地和直斜群桩桩顶承台的频谱成分进行详细分析,之后根据得出的不同频率成分分别对直斜群桩桩身弯矩分布情况进行详细研究。研究结果表明:地震荷载作用下饱和砂土液化前后土体特征频率发生明显变化,液化后土体的特征频率明显变小;随着振动强度的增加,斜桩顶承台特征频率也发生了减小的现象,而直桩桩顶承台特征频率则始终保持在0~2Hz,未发生明显变化;不同振动强度下,不同频率成分对于直斜群桩桩身弯矩包络图的影响发生了较大的变化,在0.05 g工况下0~2 Hz频谱成分对斜群桩桩身弯矩影响要小于2~5 Hz,但其他工况下0~2 Hz频谱成分对于直斜群桩桩身弯矩的影响均最为明显。同时,随着振动强度的增加,土体埋深范围内直群桩桩身弯矩包络图的峰值位置发生了下移。因此,在实际工程中应考虑此问题,适当增加弯矩较大值位置附近的桩身抗弯刚度。Under the action of seismic load,pile group is subjected to the joint action of cap and soil,and the bending moment of pile body of different pile types will change obviously,especially under the condition of saturated sand. In order to study these problems,the seismic dynamic response tests of vertical and batter pile groups in saturated sand were carried out by ZJU400 geotechnical centrifuge of Zhejiang University. The spectral components of the saturated sand and the pile cap were analyzed in detail through the method of spectrum analysis and then,the distribution of the bending moment of the piles were discussed in detail. The results show that,under seismic loading,the characteristic frequency of the saturated sand decreases obviously after liquefaction. With increasing the vibration intensity,the characteristic frequency of the pile cap of the batter pile reduces while the characteristic frequency of the pile cap of the vertical pile keeps at 0–2 Hz without significant change. Under different vibration intensities,the influence of different frequencies on the bending moment envelope of the vertical and batter pile groups is different. The influence of the frequency of 0–2 Hz on the bending moment of the piles is most obvious except for the case of 0.05 g where the influence of 0–2 Hz is less than that of 2–5 Hz. At the same time,with increasing the vibration intensity,the position of the peak bending moment of the straight group piles in the buried depth range of the soil moves down. In practice,it is suggested to appropriately increase the bending rigidity of the pile near the position where the bending moment is larger.

关 键 词：桩基础 频谱分析 直斜群桩 饱和砂土 桩身弯矩 承台–土体耦合作用 

分 类 号：TU43[建筑科学—岩土工程]