Surface Deformation In Deep Backfill Area And The Influence On Tower

High voltage transmission line is the main channel for long-distance power transmission.When the line is running,it needs to be safe and reliable.Due to the wide backfilling range and large backfilling depth,the backfill area will have a large settlement under the pressure of self-gravity stress and large area backfill,and the surface deformation is particularly complex.It is urgent problems to analyze and evaluate the stability of the tower,the stability of the tower and the scientific analysis and evaluation of the stability of the transmission lines,to predict the deformation of the transmission lines through the deep backfill zone.In this paper,the surface deformation of the deep backfill area and its influence on the transmission tower were studied taking the typical open backfilling site in Ordos as examples.The main contents are as follows.In this paper,the basic geotechnical tests on the backfill materials of an opencast in Ordos area were carried out,and the parameters such as density,moisture content,shear strength and maximum dry density of the backfilled materials were measured.The basic mechanical properties of the backfill were also obtained.The relationship between compaction coefficient,bearing capacity and settlement of backfill foundation was studied by indoor confined plate test.A typical backfill site model was established by FLAC^3D finite element software to analysis the surface deformation law of backfill area at different depths.The deformation results on the longitudinal central axis of backfill showed that the overall surface deformation law of backfill area was similar;the ground surface was vertical and sinks downward U-shaped symmetrically;and the maximum subsidence value grows linearly with the increase of backfilling depth.At the same time,the surface slope deformation presented the trend of first increasing and then decreasing,the curvature deformation might change direction;the change of the surface horizontal displacement was more complex;the horizontal displacement at the edge was fluctuating,while the middle region was relatively gentle.The influence of material properties and parameters of backfill material on surface subsidence was studied by FLAC^3D finite element.The influence of the physical and mechanical parameters of the soil（rock）layer,such as elastic volume modulus,elastic shear modulus and density,on the surface subsidence in the common range of values were obtained.The ANSYS finite element method was used to study the influence of different surface deformation on the internal force,deformation and failure form of the transmission tower.The ultimate bearing deformation values of transmission towers under different surface deformations were obtained,which provides reference for safety evaluation of the transmission tower under the surface deformation.The horizontal displacement of the limit bearing displacement of the transmission tower was translated and compared with the simulation results of the backfill site.At the same time,the virtual iron tower was set up at the special deformation point.The internal force changes of the pole parts at the most disadvantageous position of the transmission tower in the backfilling site were analyzed respectively.Considering the adverse layout of transmission lines,the influence of uneven settlement on conductor layout was analyzed.