采用一种新型螺旋锚-岩石锚复合基础（即双锚复合基础）以适应山区输电线路工程广泛存在的“上土下岩”地质条件。利用圆曲线函数对受到上拔荷载的复合基础锚周土体滑动面进行模拟，并依此建立了考虑滑动面不同位置土压力系数演变的双锚复合基础极限抗拔承载力计算公式；利用Abaqus分析了材料、几何参数和工程地质条件等对双锚复合基础极限抗拔承载力的影响并据此给出了双锚复合基础在山区输电线路应用的工程建议。结果表明，本研究提出的双锚复合基础的圆曲线极限抗拔承载力计算公式精度较高；锚片数量、螺旋锚直径及混凝土强度等级对双锚复合基础的极限抗拔承载力有显著影响，锚片数量从2片增加至6片、螺旋锚体直径从0.24 m增加至0.48 m和混凝土强度等级从C30增加至C70将分别导致复合基础极限抗拔承载力提升26.9%、75.8%和62.5%；在黏聚力较小和内摩擦角较大的土体中双锚复合基础能发挥更大的抗拔承载力，相比于内摩擦角15°土体中的双锚复合基础，内摩擦角35°土体中的复合基础极限抗拔承载力将提高74.5%。

A new type of spiral anchor-rock anchor composite foundation (i.e., double-anchor composite foundation) is adopted to adapt to the geological conditions of “soil-up and rock-down” which are widely existed in mountainous areas of power transmission line projects. Using the circular curve function to simulate the sliding surface of the soil body around the anchor of the composite foundation subjected to uplift load, and accordingly established the formula for calculating the ultimate pullout capacity of the double-anchor composite foundation considering the evolution of soil pressure coefficients at different locations of the sliding surface; established a numerical model of the double-anchor composite foundation by using Abaqus and analyzed the damage modes, materials, geometrical parameters, and geological conditions of the project for the ultimate pullout capacity of the double-anchor composite foundation. The influence of material, geometric parameters and engineering geological conditions on the ultimate pullout capacity of double-anchored composite foundation is analyzed, and accordingly, the engineering recommendations for the application of double-anchored composite foundation in mountainous power transmission lines are given. The results show that the calculation formula of the ultimate pullout capacity of the double-anchor composite foundation proposed in this study has high accuracy; increasing the number of anchor disks, the diameter of helical anchors and the strength grade of concrete will significantly improve the ultimate pullout capacity of the double-anchor composite foundation, increasing the number of anchor disks from 2 to 6, the diameter of helical anchors from 0.24 m to 0.48 m, and the strength grade of concrete from C30 to C70 will result in an increase in the ultimate pullout capacity of composite foundations by 26.9%, 75.8%, and 62.5%, respectively; the double-anchor composite foundation can play a greater pullout capacity in the soils with small cohesive force and large angle of internal friction, Compared to a double-anchored composite foundation in a soil with an internal friction angle of 15°, the ultimate pullout capacity of a composite foundation in a soil with an internal friction angle of 35° is increased by 74.5%.