| Located in the hengduan mountain range and nianqing tanggula mountain region in the central and eastern part of Tibet,the research area of tibetan-china interconnection project is a power grid project with the most complex and severe geological environment in the world due to its harsh climate,complex terrain,developed structure and frequent geological disasters.Frequent geological disasters are a great challenge to the safe operation of the network project in central Tibet.The study on the destruction mode of the tower under the action of geological disasters and the warning of tower disasters is a very effective disaster prevention and reduction work.Based on the Tibet-China networking project and on the investigation of geological disasters on the transmission lines of the Tibet-China networking project,this paper analyzes the positional relationship between geological disasters and transmission towers,and the functional relationship between geological disasters and towers,and summarizes and puts forward the failure modes of towers in the Tibet-China networking project.The landslide in Zhuba village of Baxoi County was selected.Starting from the single landslide,FLAC3 D numerical simulation software was used to study the landslide deformation under the load of the tower.The deformation parameters of flour on the top of foundation were obtained.The deformation parameters of flour on the top of foundation were used as the bearing displacement directly acting on the foot of the tower.ANSYS numerical simulation software was used to study the failure mode of the tower under the surface deformation of landslide.The relationship between ground displacement and tower failure is also studied,and the limit displacement value leading to tower failure is taken as an early warning index for tower disaster.The main achievements and understanding are as follows:(1)Through remote sensing interpretation and field investigation,a total of 39 geological disasters threatening the line were identified and investigated,including 14 landslides,10 collapses,7 debris flows,7 unstable slopes and 1 ice avalanche.Based on the analysis of the investigated disaster samples,the failure modes of transmission towers in the tibetan-china Internet project are summarized,which are deformation-destruction-type and impact-silt type.(2)The landslide in Zhuba village of Baxoi County was selected for key analysis.Through geological investigation and drilling,the basic characteristics of the landslide were found out.The volume of landslide accumulation was about 6140×104m3,and the main material was gravel soil.The elevation of the front edge of the landslide was 3491 m,the elevation of the rear edge was about 3640 m,and the elevation difference was nearly 341 m m.The longitudinal length of the landslide slope is about 980 m,the maximum is about 1050 m,and the transverse width is about 1160 m m.The average thickness of the sliding body is 54 m.The deformation mechanism of the landslide and the failure mode of the tower are analyzed.The landslide is defined as push-type landslide and the failure mode of the tower is deformation failure type through the profile shape of the landslide,the characteristics of sliding flour and the thickness distribution of accumulation body.(3)FLAC3D software is used to predict the foundation deformation under the combined action of tower and landslide,and the displacement curve of foundation under the action of landslide deformation is obtained.Through the curve,it is found that foundation colleagues are undergoing horizontal deformation and vertical deformation under the action of landslide,with Z direction(vertical direction)as the main deformation,Y direction(vertical line)as the second movement,X direction(along line)as the smallest deformation,and foundation's deformation mode is the three foundation settlement under the action of horizontal displacement.(4)Based on the deformation parameters of the flour at the top of the foundation as the displacement of the support directly acting on the tower foot of the tower,the failure mode of the tower under the landslide deformation is studied.It is found that under the landslide surface deformation,the tower topples along the line and the main material of the tower reaches the yield state first.(5)ANSYS software is used tostudy the relationship between surface displacement and tower failure.Through the established tower failure criteria,the corresponding foundation displacement threshold is calculated when the tower fails.The foundation displacement threshold is taken as the early warning index of tower disaster,and the early warning grade is divided. |
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