软岩地质条件下浅埋隧道锚缩尺模型试验

为研究隧道锚的受力变形和锚碇承载特性等问题，在重庆几江长江大桥工程北岸现场开展1∶30缩尺模型试验。试验结果表明：从相似设计荷载240 kN 到1680 kN，双锚碇前锚面沿拉拔方向的最大位移平均值为0．020～0．808 mm，双锚碇前端上部地表岩体铅直方向的最大位移值为0．028～0．749 mm，双锚碇后端上部地表岩体铅直方向的最大位移值为0．014～0．645 mm；锚碇围岩破裂类型是拉剪复合型破坏；锚碇上方地表横桥方向参与抗拔作用的岩体范围约2～3 m，而沿锚碇轴向参与拉拔作用的岩体破坏区类似一个倒塞体形状；通过试验得到模型锚的可靠抗拉拔承载能力为1344 kN；模型锚在840 kN 下的流变趋于稳定，其长期安全系数为3．5。模型试验结果表明软岩地质条件下浅埋隧道锚具有较高的抗拉拔承载能力，证明此设计方案是可行的。

Scale model test on shallow tunnel anchorage under soft rock geological conditions

In order to study the deformation and bearing capacity of the tunnel anchorage, a field model test on the scale of 1:30 was carried out on the north shore of the Chongqing Jijiang Yangtze River bridge. The follow conclusions are drawn:From the design load (240 kN) to 1 680 kN, the average maximum displacement of the front anchor face of the anchorage along the drawing direction ranges from 0.020 mm to 0.808 mm, and the average maximum displacement of the upper rock mass above the front and the rear ends of the anchorage along the vertical direction ranges from 0.028 mm to 749 mm and 0.014 mm to 0.645 mm, respectively; The failure type of the rock-anchor system is tension-shear failure; About 2-3 m range rock mass above the lateral direction of the two anchorages participates in bearing deformation, and the damage area of the rock mass along the axis of the anchorage is similar to a plug body; The reliable bearing capacity of the anchorage model under tension is 1 344 kN through the model test; The rheological behavior of anchorage model under tension of 840 kN is stable, and its long-term stability coefficient is 3.5. The results of the model test show that the tunnel anchorage has high bearing capacity under tension, thus, the design scheme is proved to be feasible.