分级荷载下压力型土层锚杆承载特性试验研究

Experimental Investigation into Load Bearing Features of Compression-Type Soil Anchors Under Step-Loading

通过室内模型试验,模拟了人工土质边坡中压力型锚杆在地面荷载作用下的工作状态,研究了分级荷载作用下各层锚杆的轴向应变特征及其随荷载作用时间的变化规律.结果表明:对于人工边坡,地面荷载作用的最危险阶段出现在荷载传递过程中,边坡的压实过程也会使锚杆承受额外荷载.小荷载作用时,处于被压实范围土体内的底层锚杆在压实作用下整体发生向下的位移,基本不受轴向力,处于压实范围外的上层和中层锚杆锚固段分担由于滑坡体发生向下相对位移而引起的较小拉力;中级荷载作用时,土体仍然处于被压实过程,各层锚杆的轴向应变沿长度分布变化不大;高荷载作用下,各层锚杆锚固段逐渐起到了加固边坡的作用,整个锚固系统共同承担坡体的下滑力,直至最后发生破坏.

By model tests, the working condition of compression-type anchors in a man-made soil slope is simula- ted under the surface-loading. Then, the axial strain characteristics of the anchor bars in each row are investigated under the step-loading, and the changes of the strain with the loading time are also discussed. The results show that （ 1 ） for a man-made slope, the most dangerous stage under the surface loading appears during the load trans- ferring, and an additional load will be added to the anchors when the slope is compacted by the surface-loading; （ 2 ） under a small load, the bottom anchors in the range of the compacted soil integrally move downward under the compaction and bear no axial force, but the top and middle anchors with their grouted sections beyond the compac- ted soil are loaded with less tension that is caused by the landslide displacement; （3） under a middle load, the soil is still in the compacted process, and the axial strain distribution of each anchor along its length shows little change ; and （4） under a high load, the anchorage sections of all anchors play a gradually active role in strengthe- ning the slope and jointly bear the slope sliding force until the slope failure.