Study On The Anchor Load Transfer Mechanism And Bearing Behavior

Anchor is widely applied in civil engineering and hydraulic engineering due to its advantages such as construction convenience,strong adaptability in various sites,great bearing capacity of single anchor,high anti-seismic ability,and good stability.In the recent twenty years,studies in anchoring characteristic of anchor are extremely active,in which the load transfer mechanism of anchor is one of the emphasis.Because of the complexity in engineering geological condition,studies considering the influence of rock and soil body material features to anchor bearing characteristic and in anchor interaction rules in group anchors are subjects of important theoretical and practical significance in current engineering anchor technology studies. By integrating National Natural Science Foundation (50878082), Hunan Natural Science Foundation (09553104) and Communication Ministry Western Project (200631880237),this paper takes intensive research in load transfer mechanism of single and group anchor.Firstly,Through comeprehensive analysies of the domestic and wold related refernces and experimental data,an in-depth study and summariztion of the anchor-soil load transfer behavior and the uplift mechanism of bolt is obtained,morevoer, under different conditions, the nature of the changes of rock and soil is obtained.Secondly, according to the mechanical characteristics of tensile anchor, this text introduces the transfer function of bilinear load, puts forward a analysis method of anchor, which is suitable for any bolt model, establishes the calculation analytical solution of anchor displacement and pull-out resistance,puts forward a judging method of anchor under different conditions, analyzes the change law of anchor load-displacement under different bolt model, and explores the effect characteristics of anchor pull-out resistance under different bolt model with examples.Thirdly,According to the law of soil parameters changing with the depth,the limited shaft resistance and the shear stiffness coefficient is assumed to be varied linearly with depth,the analytical solution of displacement and the axial force is deduced.Also in this paper,the influence of the changing of the limited shaft resistance and the shear stiffness coefficient on the displacement and axial force of anchorage body is analyzed. At last,this applied to the analysis of an experiment,and the results show that the caculated results are closed to the test value,what shows that the proposed methed is reasonable.At last,The load transfer mechanism of anchor groups is deeply analyzed based on the similar load transfer between anchor groups and piles, and the Concept of reinforcement effects for anchor groups is introduced. Based on the analysis of displacement behavior considering reinforcement effects, a basic differential equation served as the formula for the displacement calculation of anchor groups is set up, thereafter a new calculation method for the displacement calculation of anchor groups is established'with a more comprehensive consideration of anchor-anchor interaction. Also in this paper, via changing anchor intervals, diameters and lengths of anchorage body, the influence of these parameters on the displacement of anchor groups is analyzed. At last, this new method is applied to the analysis of an experiment, and the results show that the calculated results are closed to the test value. This method can be easily applied in the practical engineering and can decrease the cost of calculation.