1∶10隧道锚缩尺模型的变形及应力特性

DEFORMATION AND STRESS CHARACTERISTICS OF TUNNEL-TYPE ANCHORAGE MODEL ON SCALE 1∶10

在隧道锚现场缩尺(1∶10)模型试验中,通过多点位移计监测锚碇及围岩的变形,通过应变仪监测锚碇的应变,通过声发射监测锚碇及围岩变形发展过程,然后,对监测到的变形、应变与锚碇及围岩的声波特性进行对比分析,并结合三维数值模拟预测成果,确定隧道锚模型的变形及应力特性。研究结果表明,当荷载小于5.8~7.1 MN时,锚碇模型处于弹性变形阶段;当荷载小于19.5 MN时,锚碇模型处于弹塑性变形阶段;当载荷大于19.5 MN且小于23.7 MN时,锚碇模型处于屈服阶段;当载荷大于23.7 MN时,锚碇模型处于流变阶段。且根据塑性区的发展变化,可判断隧道锚最可能的潜在滑移面是锚碇下部与岩体之间的接触面;其次,后锚面的上部岩体有可能因拉应力过大而导致隧道锚失稳。

During field scale model test of tunnel-type anchorage,the deformation of anchorage and surrounding rock are monitored by multipoint displacement meter,the strain of anchorage are monitored by strain gauge,the deformation and its history of anchorage and surrounding rock are monitored by AE. Then,3D numerical simulation of test are also performed,the analysis is focused on the deformation and stress characteristics of tunnel-type anchorage. The results show that anchorage model undergo four phases in turn:When the load is less than 5.8–7.1 MN,the deformation of anchorage model is in elastic phase. When the load is less than 19.5 MN,the deformation of tunnel-type anchorage model is in elastic-plastic phase. When the load is greater than 19.5 MN and less than 23.7 MN,the deformation of tunnel-type anchorage mode is in the yield phase. When the load is greater than 23.7 MN,the deformation of tunnel-type anchorage mode is in rheological phase. And according to the developing of the plastic zone,the potential slip surface of tunnel-type anchorage is the bottom contact surface between anchorage and the rock mass. Rock mass above the rear anchorage would be damaged due to excessive tensile stress,which can lead to instability of tunnel-type anchorage.