Abstract: Branch-type anchor is a new type of bolt independently developed by the authors, which has broad application prospects. In order to explore the load-bearing characteristics of branch-type anchors, an indoor test model was constructed, and a series of pull-out tests was carried out for different embedding depths, branch diameters, and double-branch spacing. The corresponding load-displacement curves were obtained, and non-dimensional processing for part of the data was conducted to obtain the relationship curve between the buried depth ratio and the load factor. Finally, a simplified mechanical model was used to derive the calculation formula for the end resistance and the pull-out ultimate bearing capacity of the branch-type anchor. The research results show that there is a nonlinear relationship between the embedment depth and the ultimate bearing capacity, and a critical embedment depth exists. The plate diameter has the most significant impact on the pull-out bearing capacity, which has a linear growth relationship with the ultimate bearing capacity. The ultimate bearing capacity is 2?5 times higher than that of a straight bolt. The bearing capacity of the double plate can be fully used when the separation distance of the double plate is 4 times of the plate diameter. Since the soil is mainly sheared at the initial stage of loading, the initial slope of the load-displacement curve of the double-branch anchor is much larger than that of the single-branch anchor. The sudden change point of the slope of the relationship between the embedment depth ratio and the load factor is the critical embedment ratio, which is 3.02. The results obtained by this formula are basically consistent with those of the four testing groups, which verifies the validity of the calculation formula. The research results have important theoretical and practical significance for the design and engineering application of the branch-type anchor.

Key words: branch-type anchor, ultimate bearing capacity, pull-out tests, end resistance, clay