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| 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#br# |
| ZHANG Jian1，LI Yurun1，2，YAN Zhixiao1，RONG Xian1，2#br# |
(1. School of Civil and Transportation Engineering，Hebei University of Technology，Tianjin 300401，China；2. Civil Engineering Technology Research Center of Hebei Province，Hebei University of Technology，Tianjin 300401，China)
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Abstract 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.
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2020, Vol. 39 
