注浆抬升技术是盾构隧道不均匀沉降治理的有效措施之一,但目前尚存在隧道抬升过程上覆土压力计算困难而无法估算抬升引起的隧道受力变形的问题。利用透明土结合PIV观测技术设计研发了模拟盾构隧道抬升的小比尺室内模型试验系统,通过试验获得了隧道抬升过程极限上覆土压力及上覆土速度场,根据上覆土的剪切滑移特征将上覆土分成了4个不同的运动区域,进而结合相关联流动法则,提出了隧道抬升作用下极限上覆土压力计算模型,并基于虚功平衡方程,推导了极限上覆土压力计算表达式。将计算所得的极限上覆土压力值与试验结果进行对比,两者有较好的吻合度,计算误差在4%~15%之间。
Grouting lifting technique is considered as an effective method to dispose uneven settlement of shield tunnel; but the overlying earth pressure on the shield tunnel during lifting is complex and has not been investigated deeply, which makes it hard to estimate the stress and deformation condition of the shield tunnel lining. A small scale model test system is firstly developed to simulate shield tunnel lifting in the laboratory, in which the transparent soil and PIV technology are applied. The limit overlying earth pressure as well as velocity field of the overlying soil layer are obtained through the tests. Then the shear-slipping features are studied, which indicate that the overlying soil layer could be divided into four different motion regions. A calculation model of limit overlying earth pressure is established based on the associated flow rules together with velocity field of overlying soil layer; then the calculation formulas are derived on the basis of virtual work equation. It turns out that the calculated limit overlying earth pressures are 4%-15% higher than the results obtained from model tests.