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开展了Trapdoor试验来模拟砂土层中盾构隧道的开挖,研究了Trapdoor上部竖向土压力的转移机理,总结了国内外土拱区侧压力系数K的取值,与试验结果进行了对比并给出其建议值。分析结果表明,隧道上覆土体通过拱效应把作用在衬砌管片上的部分竖向土压力传递到两边不动土体,从而导致竖向土压力明显减小,而水平向土压力有所增加;当土拱效应充分发挥时,按侧压力系数K=1计算得到的Trapdoor上部竖向土压力与试验结果比较接近。
A Trapdoor test was conducted to simulate the excavation of the shield tunnel in the sand layer. The transfer mechanism of the upper vertical earth pressure in Trapdoor was studied. The values of lateral pressure coefficient K at home and abroad were summarized and compared with the experimental results And give its suggestion value. The analysis results show that the part of vertical soil pressure acting on the lining pipe segment is transferred to the immovable soil by the arch effect, and the vertical earth pressure decreases obviously and the horizontal earth pressure increases. When the soil arching effect is fully exerted, the upper Trapdoor earth pressure calculated by the lateral pressure coefficient K = 1 is close to the test result.