盾构隧道中细砂液化特性的小型振动台试验研究

Study on Liquefaction Characteristics of Medium-fine Sands in Shield Tunnelling with Small-size Shaking Table Test

  • 摘要: 文章以福州地铁5号线沿闽江段盾构隧道<2-5>中细砂地层为试验对象,开展了9个正交设计工况下的小型振动台试验,探究闽江砂土液化特性。结果表明:激振初期不同深度处的超孔隙水压(及超孔隙水压比)均快速累积至峰值,后略微下降并保持平稳直至激振结束;各地震动因素对砂土液化的影响程度依次为输入波振幅>输入频率>砂土饱和度;浅部砂土地层的液化可能性更大,在设计地震、罕遇地震、巨震作用下分别发生轻微液化、中等液化、完全液化。该试验结果可为后续数值模拟的参数标定提供依据,为闽江沿岸的工程建设提供参考。

     

    Abstract: As for the <2-5> medium-fine sand stratum, in which the shield tunnel section of Fuzhou Metro Line 5 along Minjiang River locates, the small shaking table tests are performed under 9 orthogonal design conditions to explore the liquefaction characteristics of Minjiang sands. The results show that the excess pore water pressures and excess pore water pressure ratios at different depths quickly accumulate to the peak values in the initial excitation stage, then drop slightly and finally remain stable until the end of the excitation; the influence degrees of various factors on liquefaction of sands are ranked as follows: input wave amplitude>input frequency>soil saturation; for the sand stratum at shallow depth, it has higher liquefaction possibility, and slight, medium and complete liquefaction events might occur under action of designed earthquake, rare earthquake and huge earthquake, respectively. The test results can provide a basis for the parameter calibration in subsequent numerical simulations and a reference for engineering construction along the Minjiang River.

     

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