| Fabricated anchor cable frame beam is a new slope reinforcement structure developed based on cast-in-situ anchor cable frame beam.It has the advantages of high mechanization,controllable component quality,short construction period and low labor cost.It can effectively reduce the landslide risk during construction.It is one of the new directions of the development of slope disaster prevention technology.In order to implement the national policy of prefabricated construction industry and complete the target task of "all access" project of county Expressway in Yunnan Province,a largescale field experimental study of prefabricated anchor cable frame beam was carried out in a bid section of Mengzi Pingbian Expressway in Honghe Prefecture,Yunnan Province,to study the internal force calculation method of new anchor cable frame beam and the mechanical performance of prefabricated anchor cable frame beam.The feasibility of using fabricated anchor cable frame beam for slope reinforcement is verified by field test,which can replace the cast-in-situ anchor cable frame beam.In the aspect of theoretical research,the following work is carried out: 1.considering the influence of shear modulus on the internal force of beam,the difference of stress and deformation of frame beam calculated by Euler Bernoulli beam theory and Timoshenko beam theory is analyzed.2.Based on Timoshenko beam theory and considering the interaction of adjacent anchoring forces,the iterative method is used to calculate the anchoring force distribution,and a new calculation method of the anchoring force distribution of frame beam is studied,which is verified by combining the slope anchoring project of Yunnan mengping Expressway and the slope anchoring project of Gansu Chunchang Expressway.3.The numerical model is established by using ABAQUS finite element simulation software to analyze the reliability of Euler Bernoulli beam theory and Timoshenko beam theory.The comparison results show that the theoretical calculation results are consistent with the numerical calculation results in the analysis of settlement deformation,shear and bending moment.Further analyze other factors affecting the internal force of frame beam: Winkler foundation model and elastic half space foundation model,Overall stiffness of frame beam,etc.In the field test analysis,the following results are obtained: 1.carry out the field engineering test of slope anchorage of Yunnan Mengzi Pingbian expressway.The test is mainly divided into three test stages: post tensioning prefabrication of reinforced concrete beam,hoisting and transportation and slope anchorage.There is no crack in the beam during anchorage loading,which meets the design requirements.2.Collect the test data of each stage of concrete anchor cable dynamometer,reinforcement stress meter,concrete surface strain gauge and earth pressure box,and analyze the internal force of three different frame beams by ABAQUS numerical simulation.3.The monitoring data and calculated bending moment of the steel bar meter embedded on the beam are analyzed,and the internal forces of the fabricated unconnected beam,the fabricated coupling beam and the cast-in-situ beam are compared.The comparison results show that:(I)all three can bear the design anchoring force of 600 k N;(II)the stress of reinforcement and anchoring force are basically linear,and the three beams are in the elastic range;(III)the maximum bending moment of fabricated connected beam and fabricated unconnected beam is lower than that of cast-in-situ beam.4.ABAQUS modeling is used to simulate the internal forces of fabricated non connected beam,fabricated connected beam and cast-in-situ beam.Compared with the internal forces obtained from field measurement and analysis,the two are in good agreement. |
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