饱和大厚度砂土地基中长短碎石桩屏蔽效应及其抗液化评价

Shielding effect and evaluation of liquefaction resistance of long-short gravel piles in saturated large-thick sand foundation

针对阿喀公路AK-3标段饱和大厚度砂土地基存在的地震液化问题,虽然工程中采用强夯法处理但抗液化检测表明并不能解决地基液化。碎石桩是一种有效的地基液化处理措施,但采用经济的长短碎石桩在处理饱和大厚度砂土地基中抗液化性能评价的相关研究较少。本研究提出了经济、合理的长短碎石桩加固大厚度砂土地基的方案,基于弹塑性动力固结理论和三维动力固结有限元程序FEMEPDYN,对比分析了天然地基和长短碎石桩加固地基的震陷、动孔压分布及超静孔压比。研究结果表明,采用长短碎石桩加固处理后的饱和大厚度砂土地基震陷降低了86. 7%,动孔压降低了89. 3%,超静孔压比降低了89. 5%,路基两侧长碎石桩对地震波传播具有一定的屏蔽效应。长短碎石桩加固方案对砂土地基抗液化效果明显,长短碎石桩处理饱和大厚度砂土地基是一种经济有效的处理措施。

In order to solve the earthquake liquefaction problem in the saturated large-thick sand ground,the dynamic compaction was assumed in the AK-3 section of the Aka Highway,but the anti-liquefaction test showed that the threat of foundation liquefaction was still existed. Although the gravel pile is an effective treatment measure for anti-liquefaction,there are less corresponding researches on the evaluation of the anti-liquefaction performance about the long-short gravel piles in dealing with saturated large thickness sand foundation. In this study,an economical and reasonable long-short gravel pile to reinforce the large-thick sand foundation was proposed. Based on the elastic-plastic dynamic consolidation theory and the three-dimensional dynamic consolidation finite element program FEMEPDYN,the dynamic responses of the natural foundation and the reinforcement foundation were compared and analyzed,including seismic subsidence,dynamic pore pressure and excess pore pressure ratio. The results show that the seismic subsidence of saturated large-thick sands treated with long-short gravel piles is reduced by 86. 7%,the value of dynamic pore pressure is decreased by 89. 3%,and the ratio of excess pore pressure is reduced by89. 5%. Long gravel piles on both sides of the roadbed generate a certain shielding effect on the propagation of seismic waves. The anti-liquefaction effect is obvious on sand foundation by long-short gravel pile reinforcement scheme,which is a cost-effective treatment method for treating saturated thick sand foundation.