Fundamental study on single anchor and anchor-reinforced systems.

摘要

Anchors have been successively used for in-situ soil reinforcement, slope stabilization and deep excavation support. Understanding of the behavior of an anchor and the performance of the anchor reinforced structures is essential to achieve an efficient design. In this study, focus is placed on the fundamental study of the load-carrying and load-displacement behavior as well as the performance of the anchor reinforced system.; First, the analytical solutions based on the linear elastic-perfectly plastic model for the interface between the anchor and soil was derived. The parametric study has been extensively carried out, which provides insights into the anchor-soil load transfer mechanism. Secondly, the soil dilatancy effect was described based on both lab and field observations. Considering this effect, the anchor-soil interface models have been developed for the hardening and softening behavior. Using the developed interface model, the forward and backward calculation algorithms have been formulated and applied to predict the anchor performance for the given interface parameters, and to determine the interface parameters from the given anchor pull-out test, respectively. Thirdly, combining the derived analytical solutions for the anchor-soil interaction, a displacement-based approach for the stability analysis of anchor reinforced slope has been developed. The procedure allows for evaluation of the working forces in the anchor, the global factor of safety, and the limits of the anchor working force. Finally, a tieback wall system was studied via a simple finite element based computational algorithm, which allows for taking into consideration of construction sequence such as excavation, installation of tiebacks, and pre-stressing of the tendon.; The main contributions of this dissertation work consist of (i) the development of a comprehensive soil-anchor model, taking into account of the effects of dilatancy, influence zone, and confining pressure, and (ii) the development of truly displacement based analytical solution for soil nail structure, which determines the global and local factor of safety of the system as a function of slope movements. Both contributions will allow engineer to analyze and design the anchor reinforced structures with more appropriate analytical tools.