Study On Mechanical Performance Of Anchor Cable Anchorage Section For Prestressed Concrete Spiral Case

Concrete spiral case structure is one of important part in the hydropower house.It is easy to crack under the influence of loads such as internal water pressure.The pre-stressed concrete spiral case structure can be used in order to meet the crack limiting requirements of concrete spiral case structure,which can reduce the amount of reinforcement amount and improve the stress properties.The tension load of anchor cables in pre-stressed concrete spiral case is generally large.The arrangement of the anchor cable is affected by the volute type,and the length of the anchor section is limited.Therefore,it is necessary to study the anchoring characteristics of pre-stressed anchor cables.In this paper,a 1:1 simulation model test is conducted for the vertical anchor cable of a pre-stressed spiral case,which measures the ultimate bearing capacity of pre-stressed anchor cables with different anchorage lengths,the strain change of grouting body and steel strand in anchorage section of anchorage cable in different tensile loads.The finite element software ANSYS was used to carry out numerical simulation analysis of this experiment.Comparison of experimental data and numerical simulation results to evaluate the accuracy of numerical simulation results.The main research contents of this paper are as follows:(1)For pre-stressed anchor cables with expanded anchorage cable and the anchoring segment length of 5.0m,4.5m,and 4.0m,we performed 1:1 simulation model test.The test measured the carrying capacity of the anchor cable and the strain distribution of the grouting body and steel strands of the pre-stressed anchor cables under different tension loads during the tensioning process.The result shows that the destructive form of the anchor cable is steel strand's wire was fractured and the three schemes of different anchoring segment length can all meet the design requirements.(2)Considering the material nonlinearity of the grouting body and the nonlinear contact between the grouting body and the steel lining,the tension process of model test was simulated numerically.The calculation results show that the numerical simulation method can accurately simulate the strain change of steel strand and grouting body under the action of tensile load.The use of an expanded head anchorage cable structure can effectively combine the grouting body and the concrete part under the action of tensile loads.Most of the tensile load is transmitted to the concrete by expanding the tip part of the grouting body.(3)Sensitivity analysis of the friction coefficient between the grouting body and the steel liner shows that changing the friction coefficient has no significant effect on the strain in the grouting body.