隧道锚抗拔作用机理的室内模型试验

通过室内模型试验对隧道锚的抗拔作用机理和承载能力进行了研究,设计加工了隧道锚室内模型装置,通过多种配比材料的强度和变形试验确定了用于模拟隧道锚区现场围岩的相似材料,采用多种监测手段进行了隧道锚拉拔荷载作用下地表和围岩内部的变形、应变和应力监测.结果表明:在拉拔荷载的作用下,锚塞体顶部靠近地表的岩体先进入拉破坏,随着锚塞体的传力作用,锚塞体与围岩接触部位侧摩阻力逐渐达到极限,然后荷载逐渐传递到围岩内部,锚塞体附近围岩进入剪切破坏,个别部位为拉破坏,围岩破坏形态为从锚塞体底部向上发散的倒锥型破坏面.隧道锚承载能力由两部分组成:1锚塞体和围岩接触面的极限摩阻力;2围岩剪切-拉破坏的极限阻力,即夹持效应.50倍设计缆力下围岩处于弹性阶段,这表明目前的隧道锚设计是偏于保守的,存在进一步优化的空间.

Laboratory Model Test Study of Pullout Mechanism of Tunnel Anchorage

Abstract： A laboratory model test of tunnel anchorage was conducted to investigate its pullout mechanism and bearing capacity. First, a laboratory model test device was designed and produced. Second, through the strength and deformation test, the material ratio was determined to simulate tunnel rock. Third, the surface and rock deformation, strain and stress were measured during the entire test process. The results show that, under pulling loads, tensile failure first occurs in top surface rock near the anchorage, then shear failure occurs in the rock around the anchorage. The failure surface is inverted cone from the anchorage bottom. The bearing capacity of the tunnel anchorage consists of two parts. The first part is the ultimate friction resistance in the interface of anchorage and rock while the second part is the rock shear tensile resistance namely clamping effect. Under 50 times design cable force, the tunnel rock is in elastic stage, suggesting that the current tunnel anchorage design is quite conservative and can be further optimized.