采空塌陷区地表变形作用下门型拉线塔破坏机理的试验研究OA

Ground deformation induced by mined-out subsidence can cause the displacement of transmission tower foundations,posing a serious threat to the safe operation of power lines.Guyed portal towers are particularly vulnerable to such deformation due to their structural characteristics including a wide foundation span and hinged joints at the column bases.This study selects a typical guyed portal tower as the research object to develop a scaled steel structural model and a three-dimensional ground deformation hydraulic servo loading system based on similarity theory.Using measured field deformation data,destructive loading tests are conducted to simulate the coupled effects of differential settlement and horizontal ground movement.By monitoring and analyzing the responses of guy wire tension,support reactions,tower-top displacement and member strain,the study systematically reveals the complete failure mechanism of the tower.The results show that at the early stage of ground deformation,when the differential settlement reaches approximately 31 mm,the guy wires begin to slacken,leading to a significant reduction in the tower's lateral restraint stiffness.With increasing out-of-plane horizontal displacement of the foundation,the cross-arms and tower legs gradually rotate,and when the displacement reaches 290 mm,the structure exhibits a pronounced coupled inclination-torsion deformation.The strain measurements indicate that no material yielding occurred in any members and the failure mode is dominated by overall instability induced by large geometric deformations.The proposed scaled model testing method can effectively simulate stress and failure mechanism under the effect of three-dimensional compound ground deformation.The findings provide technical references for the structural optimization,safety assessment,and operational monitoring of portal towers in the mined-out subsidence areas.