Abstract: The key construction procedures of the composite foundation of the expanded base pier and the rock anchor in mountainous areas include design method, installation and cost comparisons, standardized foundation design and construction procedures. The design method mainly involves the selection of the coefficient of bearing capacity. Based on the numerical simulation and the current test results, the suggestions for the selection of k1 and k2 are proposed in the paper. Under the local geological conditions, loads acting on the proposed foundations and state-of-the-practice construction conditions, the combination of expanded base pier with rock anchor is proved to be cost effective. Through the determination of design principles of expanded base pier part and anchor part, the suggestions of anchor reinforcement arrangement under different diameter of main pier are proposed. In the Luoyuan Bay Power Plant-Bili 220 kV power transmission line project, 17% of the foundations are composite foundation of expanded base pier with rock anchor, the result shows that this composite foundation receives cost, social and environmental benefits.

Key words: expanded based pier with rock anchors, coefficient of bearing capacity, standardized foundation design, construction procedures