对盾构施工引起的隧道轴线上方土体超孔隙水压力和工后地面沉降进行研究,提出盾构隧道施工引起的土体应力释放率计算方法。基于Henkel超孔隙水压力理论,推导与隧道衬砌相邻的土体初始超孔隙水压力值。假定与衬砌相邻的各点具有相同的应力释放率,得到隧道拱顶处土体的超孔隙水压力计算方法。运用应力传递理论,提出隧道轴线上方土体的超孔隙水压力分布模式。假定压缩层厚度为隧道覆土厚度,采用太沙基一维固结理论,得到隧道轴线上方地面工后固结沉降理论计算公式。算例分析结果表明,该方法的预测值与实测值非常吻合。
Excess pore pressure and post-construction consolidation settlement of soil above tunnel axis caused by shield tunneling were studied. A calculation method for stress release rate caused by shield tunneling was put forward. Based on the Henkel pore water pressure theory, the excess pore water pressure of soil adjacent to the tunnel lining was deduced. Supposing that the points around the lining have the same stress release rate, the calculating method for excess pore water pressure of soil at tunnel arch crown was obtained. Using the theory of stress transfer, the distribution mode of excess pore water pressure above the tunnel axis was proposed. Assuming that the thickness of compressed soil equals that of the soil above tunnel, the theoretical calculation formula for consolidation settlement of ground above the tunnel axis was suggested based on Terzaghi's one-dimensional consolidation theory. The results of case study show that the calculated results are in good agreement with the measured data.