基于透明土的隧道上浮过程结构与土相互作用模型试验

Model Test on Upward Moving Tunnel and Soil Interaction Using Transparent Soil

上覆土地基弹簧系数取值是盾构隧道纵向上浮计算的关键问题之一,该值的选取取决于隧道与土的相互作用特征,但该特征较为复杂且研究缺乏。为研究上浮过程隧道与土的相互作用特征,基于透明土设计了模拟盾构隧道上浮过程的小比尺室内模型试验系统,可得到不同上浮量下的抗浮力,同时结合PIV系统可实现非接触式地观测隧道上浮过程中土体内部连续位移场。通过一模型试验对系统功能进行了详细描述,并基于该组试验分析了抗浮力随上浮量变化规律及隧道周围土体位移场变化规律。研究结果表明:抗浮力随着上浮量增大而增大,但增大速率减小,当上浮量达0.1倍隧道外径时,抗浮力达峰值;隧道周围局部范围土体位移场近似呈现为漩涡状。

The stiffness selection for foundation spring of overburden soil, as one of the intractable problems in longitudinal upward movement analysis of shield tunnel, depends on tunnel and soil interaction, which is complex and in lack of deep research at present. To probe into upward moving tunnel and soil interaction, based on a small-scale model indoor test system simulating shield tunnel upward movement, this study got anti-buoyancy during upward moving and non-contact observation of internal displacement field with PIV technology. On the basis of a model test for a detailed description of the system＇s functions, it finally analyzed the relationship between anti-buoyancy and upward displacement and soil displacement field features around tunnel. Results show that the anti-buoyancy increases with the increase of upward displacement of the model tunnel, but the increasing rate decreases. And the anti-buoyancy reaches peak value when the model tunnel upwardly moves to 0.1times of the outer diameter of the model tunnel. The results also show that the displacement field around the model tunnel presents an approximately swirling pattern.