为获取土岩复合地层最优锚固长度，采用室内试验、数值模拟、工程测试等方法，围绕是否穿过黏性土砾砂岩层，针对2类锚固长度（12 m、8 m）工况进行研究。结果表明： 1）在张拉载荷作用下，剪应力峰值由锚固段起始点向尾部转移，而锚固在含黏性土砾砂岩层中的剪应力峰值低，轴力衰减速率高。2）随张拉载荷的增大，锚固在黏性土砾砂岩层中的锚固段由拉应力区逐渐转化为压应力区，应力向深处的传递速率低，锚固体具有抵抗外载荷能力差、变形量大的特点。3）锚索轴力可分为预应力损失、上升、波动3个演化阶段，而锚固段穿过黏性土砾砂岩层时，预应力在波动阶段出现损失，且在不同方向上的预应力呈现非均匀分布特征。4）在锚索穿过土岩复合地层时，应避免锚固在含土砾砂地层中。
To obtain the optimal anchorage length for soilrock
composite strata, indoor tests, numerical simulations, and engineering tests
are conducted to investigate the working conditions for two types of anchorage
lengths (12 m and 8 m). The results show the following: (1) The peak shear
stress transfers from the beginning to the end of the anchorage section under
the tension load, while the peak shear stress is low and the axial force decay
rate is high in the anchorage in clayey soil gravel sandstone layer. (2) With
the increase of tension load, the anchorage section in clayey soil gravel
sandstone layer gradually transforms from tensile stress zone to compressive
stress zone, the transfer rate of stress to the depth is low, and the anchorage
solid has the characteristics of poor resistance to external load and high
deformation. (3) The anchor cable axial force can be divided into three
evolutionary stages: loss of prestress, rise, and fluctuation, and when the
anchorage section passes through the clayey soilgravel
sandstone layer, the prestress is lost in the fluctuation stage, and the
prestress is nonuniformly distributed in different
directions. (4) It is recommended to avoid anchoring in the soilgravel sandstone layer when the anchor cable passes through the soilrock composite strata.
