抗滑桩静力与动力破坏离心模型试验对比分析
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摘要
在探讨边坡中抗滑桩的加固效果时,应该重视混凝土抗滑桩不同条件下破坏规律的研究。采用研制的微混凝土抗滑模型桩,通过动力离心模型试验研究了两种情况下的破坏特点。一种情况是混凝土抗滑桩一侧静力开裂后受地震作用继续开裂至完全断桩,另一种情况是静力条件下稳定的边坡加固桩在地震作用下桩底发生开裂。根据试验观察以及试验结果对比分析了微混凝土抗滑桩在两种不同条件下开裂破坏过程中弯矩分布特点:静力开裂后在地震作用下桩底嵌固约束转化为活动铰约束,其弯矩始终呈抛物线形分布,只是其峰值随时间发生变化;静力条件下稳定的加固桩在地震作用下,其弯矩先有较大增加然后又由于桩底一侧开裂而下降较多,并且小于震前静态弯矩。
The effect of crack failure of stabilizing piles on the global static and dynamic stability of soil slopes should be properly evaluated in order to check the design in practice.Two dynamic centrifuge tests on soil slopes reinforced by model concrete piles were performed.In model test 1,cracks occurred at the ends of piles due to the static load and the piles were broken completely after the excitation of an earthquake.In model testz,the piles worked well during the static state and the cracks occurred at the ends of piles during the earthquake.According to the observation and the test results,the characteristics of moment distribution in the two different crack failure patterns could be compared.In model test 1,because of cracks due to the static load,the moment distribution in model concrete piles presented the trends of parabola shape from the beginning of the excitation of the earthquake,and the fixed ends of piles converted to the hinge joints.In model test 2,the moment in piles increased firstly and then decreased owing to the cracks resulted from the earthquake and finally the residual moments were less than the values in the static state.
The effect of crack failure of stabilizing piles on the global static and dynamic stability of soil slopes should be properly evaluated in order to check the design in practice.Two dynamic centrifuge tests on soil slopes reinforced by model concrete piles were performed.In model test 1,cracks occurred at the ends of piles due to the static load and the piles were broken completely after the excitation of an earthquake.In model testz,the piles worked well during the static state and the cracks occurred at the ends of piles during the earthquake.According to the observation and the test results,the characteristics of moment distribution in the two different crack failure patterns could be compared.In model test 1,because of cracks due to the static load,the moment distribution in model concrete piles presented the trends of parabola shape from the beginning of the excitation of the earthquake,and the fixed ends of piles converted to the hinge joints.In model test 2,the moment in piles increased firstly and then decreased owing to the cracks resulted from the earthquake and finally the residual moments were less than the values in the static state.
引文
[1]BOULANGER R W,CURRAS C J,KUTTER B L,et al.Seismic soil-pile-structure interaction experiments and analyses[J].Journal of Geotechnical and Geoenvironmental Engineering,1999,125(9):750–759.
[2]TAJI Y,SATO M,YANAGISAWA E.Modeling of a prototype soil-pile-structure system during seismic ground liquefaction[C]//Centrifuge 98.Rotterdam:A A Balkema,1998:283–288.
[3]SATOH H,OHBO N,YOSHIZAKO K.Dynamic test on behavior of pile during lateral ground flow[C]//Centrifuge 98.Rotterdam:A A Balkema,1998:327–332.
[4]于玉贞,邓丽军.抗滑桩加固边坡地震响应离心模型试验[J].岩土工程学报,2007,29(9):1320–1323.(YU Yu-zhen,DENG Li-jun.Centrifuge modeling of seismic behavior of slope reinforced by stabilizing pile[J].Chinese Journal of Geotechnical Engineering,2007,29(9):1320–1323.(in Chinese))
[2]TAJI Y,SATO M,YANAGISAWA E.Modeling of a prototype soil-pile-structure system during seismic ground liquefaction[C]//Centrifuge 98.Rotterdam:A A Balkema,1998:283–288.
[3]SATOH H,OHBO N,YOSHIZAKO K.Dynamic test on behavior of pile during lateral ground flow[C]//Centrifuge 98.Rotterdam:A A Balkema,1998:327–332.
[4]于玉贞,邓丽军.抗滑桩加固边坡地震响应离心模型试验[J].岩土工程学报,2007,29(9):1320–1323.(YU Yu-zhen,DENG Li-jun.Centrifuge modeling of seismic behavior of slope reinforced by stabilizing pile[J].Chinese Journal of Geotechnical Engineering,2007,29(9):1320–1323.(in Chinese))
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