拱脚局部加长锚杆锚固洞室抗爆模型试验研究

MODEL TEST STUDY OF ANTI-EXPLOSION CAPACITY OF ANCHORED TUNNEL WITH LOCAL LENGTHENING ANCHORS IN ARCH SPRINGING

根据Froude相似理论,开展拱脚局部加长锚杆和等长锚杆加固洞室抗爆对比模型试验,分析各洞室受力变形特性和围岩破坏形态。研究结果表明:与等长锚杆相比,在爆心离洞室很近的极端情况下,拱脚局部加长锚杆起到"密闭"爆炸荷载的作用,增大洞室拱部的爆炸荷载,带来洞室拱顶底板相对位移的快速增长;在爆心离洞室较远的一般情况下,拱脚局部加长锚杆具有承担或转移较多爆炸荷载的作用,不仅能明显减小洞室附近的爆炸压力、洞室拱顶底板相对位移、拱脚压应变峰值和残余值,而且还能明显减少和减轻围岩裂缝数量和开裂程度,有效阻断裂缝的发展和延伸,有利于提高洞室的抗爆能力。

Based on Froude similarity law,contrast model test on anti-explosion capacity of reinforced tunnels with local lengthening anchors in arch springing and equal length anchors is carried out.Mechanical and deformation characteristics and failure patterns of anchored tunnels are analyzed in the test.The research results indicate that,compared with equal length anchors,on one hand,under the extreme condition,when explosion center is very close to the tunnel,local lengthening anchors in arch springing have a closure effect on explosion load;and it can increase the explosion load on arch and the increment speed of relative displacement between vault and footwall.On the other hand,under the general condition,when explosion center is slightly far away from the tunnel,local lengthening anchors in arch springing can share or divert more explosion load;and consequently explosion pressure around tunnel,relative displacement between vault and footwall,the peak and residual values of compression strain at arch springing are decreased radically.Furthermore,the number of cracks in adjacent rock can be decreased and cracked degree are alleviated by preventing cracks from engendering and extending;namely it is propitious to enhance anti-explosion capacity of the tunnel.