Analytical Method for Interfacial Slip Failure Processes Based on UFL Bond-Slip Model: Study of Grout/Soil Anchorage Interfaces in Earthen Sites

The slip debonding of grout/soil interface is the main reason for the failure of pressure-type anchorage system in earthen sites. In practical engineering, the mechanical behavior of these systems varies with the interface roughness. However, the existing analytical methods of anchorage mechanism are mainly based on the fixed-form interface bond-slip models, limiting its applicability to different types of interfaces. Thus, a unified four-linear (UFL) bond-slip model based on adjustable piecewise slope is proposed, by which the characterizations of bi-linear elastic-perfectly plastic, tri-linear plastic softening, and four-linear plastic hardening–softening models that may occur at the grout/soil interface are unified. Based on the UFL model, an analytical method for the full-range bond-slip process of interface is established. Meanwhile, the formula of bond stress distribution for each stage is derived, and the analytical solution of ultimate bearing capacity is given. The theoretical values of load–displacement curves before peak load are nearly in line with the experimental values. Moreover, anchorage length, modulus of grout, main energy-dissipation stage and slopes will significantly affect the mechanical behavior of anchorage system. Finally, the feasibility of applying this method to other four types of established bond-slip models is studied, further extending its applicability to different types of interfaces.