平行盾构开挖离心机模拟试验研究

通过离心模型试验模拟平行盾构隧道近接开挖施工,研究了盾构隧道近接开挖对既有隧道结构内力、管片变形和地表沉降的变化规律。结果表明:1隧道开挖引起地表沉降的大小与开挖的步骤有关,而沉降槽的范围基本不变;2既有隧道靠近新建隧道一侧受拉,这一侧弯矩出现负增量,侧向土压力也有一定的减小,且既有隧道直径水平向变大,而垂向直径基本不受影响;3由于土拱效应,新建隧道已完成开挖部分管片拱顶的土压力随开挖进程先减小后增大;4采用地层结构法可以准确模拟隧道开挖过程的隧道结构力学特性与变形规律。

Centrifugal model tests on excavation of twin parallel tunnels

The excavation construction of twin parallel tunnels is simulated by using centrifugal model tests. The internal stress and deformation variation of shield structure of the existing tunnel and the ground surface settlement are studied owing to excavation of the new adjacent tunnel. The research results show that: (1) The ground surface settlement relates with the tunnel excavation process, and the settlement trough range is independent of the tunnel excavation process. (2) The shield structure side of the existing tunnel near to the new constructing tunnel is subjected to tension and the bending moment at the same side of the existing tunnel has a negative increment, the transverse diameter increases, and the lateral earth pressure decreases at the same side of the shield near to the new construction tunnel. However, the vertical diameter of the shield structure of the existing tunnel is not affected. (3) The crown earth pressure of the just completed shield firstly decreases and then increases during the sequent excavation process. (4) The proposed method for the stratigraphic structure by the authors can be used to analyze the internal stress and deformation of the shield structure for tunnel construction.