The Model Test Of The Self-anchored Loading Test Technology And Results Analysis

With the increasing request of the superstructure to bearing capacity and settlement of the foundation, pile foundation has extensive application in engineering practices because of its much merit. Using an economical and effective method to test the vertical bearing capacity of pile, is not only the requirement of existing criterions, but also the topic of important theoretical and practical significance in the area of pile foundation. Presently, self-anchored loading test technology of pile foundation is a new application technology. There is a deficiency of systematic and thorough research on the mechanics property of the anchoring bolt under pile toe and the pile-soil-bolt interaction. By integrating with the Construction Technology Projects of Hunan Province(NO.200403), this paper discussed the uplift mechanism and design method of bolt, also the bearing capacity of pile foundation, in the self-anchored system. Mainly research and investigation are done as the following:Firstly, Through comprehensive analyses of the domestic and world related references and experimental data, an in-depth study and summarization of the pile-soil load transfer behavior and the uplift mechanism of bolt is obtained. Based on Introducing the calculation method offered by Code for the rock socketed pile and the bolt ultimate strength calculation method, leading the axial Winkler model into the calculation of bolt-deformation, derived the expression of the slope of the P~s curve of the bolt, based on the in-depth analyses of the pile-soil load transfer behavior and the uplift mechanism of bolt, the theoretical explanation of pile-soil-bolt interaction in the self-anchored system is obtained. And the enhanced action mechanism that the bolt under pile toe do to the pile end bearing capacity and the pile side resistance have been researched on the base of Meyehof presumption and Touma's arch-formation theory.In order to study the self-anchored test of pile-anchor interaction, based on the theory above, design and do the vertical pile-bearing capacity of self-anchored test in the laboratory, completed a single vertical pile-bearing capacity test, a single bolt pull-out capacity test, pile-anchor combination system bearing capacity test and pull-out test, have been derived the load-displacement curve of the pile in different depth in the rock , the load-displacement curve of the anchor under the different drawing load and axial force distribution, the load-displacement curve of the pile-anchor system and compared with the theoretical value. At the same time studying the effect of e the length of the bolt at the bottem of the pile on the ultimate bearing capacity of the pile.Finally, based on the ADINA software of the finite element analysis, established the two-dimensional plane model of the self-anchored system, according to the results of numerical simulation and combined with the test data, derived the receempirical relationship between the length of anchor bolt at the bottem of pile and the slope of the Q~s curve and ultimate bearing capacity of the pile.