砂卵石地层盾构开挖面失稳破坏模型试验研究

Model Test Study on Instability and Failure of Shield Excavation Face in Sandy Cobble Stratum

为了探究砂卵石地层盾构掘进过程中地表沉降规律及开挖面失稳破坏机理,以清华园隧道盾构工程为依托,利用ф280 mm模型盾构试验平台开展盾构掘进模型试验.试验结果表明:盾构掘进过程中,由于刀盘的旋转扰动,砂卵石地层横断面地表沉降槽关于隧道中心线非对称分布,且地层损失越大非对称分布越显著;另一方面,盾构开挖面失稳破坏由地中发展至地表存在滞后现象,同时刀盘的旋转方向对地表塌陷坑的位置有直接影响,塌陷坑中心位于刀盘旋转的切线垂直向上时的一侧,在实际盾构隧道工程中需要对该问题重点关注.

To explore the surface settlement law and the instability and failure mechanism of excavation face during shield tunneling in sandy cobble stratum, based on the shield project of Tsinghua Park tunnel, a shield tunneling model test was carried out in sandy cobble stratum by using the ф280 mm model shield test platform. The test results show that the transverse surface settlement trough is distributed asymmetrically towards the tunnel axis in sandy cobble strata, and the greater the stratum loss, the more significant the asymmetric distribution due to the rotation of the shield cutter head. On the other hand, the face active instability and failure develops from ground to surface with a lagging phenomenon. Meanwhile, the rotation direction of the cutter head has a direct effect on the location of the surface collapse pit. The center of the collapse pit is located on the side where the tangent of the cutter head rotates vertically upwards, which needs to be paid attention to in actual shield tunnel engineering.