大断面隧道模型试验水压模拟加载方法

首先采用结构力学方法确定隧道拱部、仰拱部分不等值环箍力模拟水荷载,研制了马蹄形断面隧道模型试验的全周密闭非均匀水压加载装置,实现“灯泡型”水压模拟加载。在此基础上进行模型试验,所得结论与数值模拟在关键部位受力结果相吻合,从而验证了水压模拟加载方法的正确性,成功解决了隧道结构试验中水压模拟加载“瓶颈”问题。在水压作用下,衬砌底部弯矩大于拱部,仰拱向内和墙脚向外弯矩最大,处于大偏心受拉截面,成为高水压隧道衬砌关键控制部位。确定了高速铁路双线隧道衬砌水压极限承载力,墙脚先发生压剪破坏,接着仰拱出现压弯破坏。研究成果可为高水压隧道主体结构设计、施工提供参考。

LOADING SIMULATION OF WATER PRESSURE FOR MODEL TEST OF LARGE-SPAN TUNNEL

Based on structural mechanics, the different hoop forces on upper and under a tunnel are determined to simulate water pressure in the first place. The fully-sealed hydraulic loading device for horseshoe-section tunnel-model tests was manufactured, which implements non-uniform hydraulic loading successfully. A model test were carried out to investigate its mechanical characteristics. The test conclusions are consistent with those of numerical simulation for controlled safe locations, which would verify the validity of the loading simulation for water. It solves the ‘bottleneck’ problem of water pressure loading during the model test of a tunnel. Under water pressure, the moment at the invert is more than that at the arch. The moment at the invert towards interior and that at the wall-footing is outwardly. A large eccentric tensile crack appears. The invert and wall-footing are deemed as controlled safe locations of lining. The ultimate bearing capacity of two-lane tunnel lining for high-speed passenger railway is determined under water pressure. Compressive-shearing damage takes place at the wall-footing. The bending destruction appeared at the invert. The results can provide a reference for the design and construction of a tunnel subjected to high water pressure.