高地应力隧道岩爆破坏特征物理模型试验研究

Failure Characteristics Analysis on Physical Model of Rock Burst in High In-situ Stress Tunnel

采用岩爆相似材料制作大尺寸物理模型,自主研制隧道开挖装置,进行二维应力隧道岩爆物理模型试验,研究高地应力条件下(侧压力系数λ=2)隧道围岩岩爆等脆性破坏特征。试验结果表明:隧道开挖后,围岩有较明显的压应变波动和突变现象,拱墙处局部出现拉应变;同时,声发射能量表现出剧烈增大现象,在应变、声发射特征这两方面均表现出高应力区隧道岩爆的征兆。高地应力条件下(侧压力系数λ=2),隧道拱顶和拱底压应力集中明显而最早发生破坏,拱墙出现拉应力作用,产生张拉裂缝。围岩脆性破坏从颗粒弹射开始,随后变为碎块剥落和裂缝扩展,其变形破坏特征表现出一定的岩爆特性。

In order to study the brittle failure characteristics of tunnel such as rockburst under high in-situ stress conditions(the lateral pressure coefficient λ = 2),a type of similar material of rockburst was selected to produce a large-size model and the tunnel excavation system was fabricated to perform the physical simulation test of rockburst under two-dimensional stress and high in-situ stress conditions. Some test results are as follows: after excavation,the surrounding rock respectively produce the obvious catastrophic phenomena of compressive strain and tensile strain occurred on the partial of side walls,and the acoustic emission energy of surrounding rock also increase rapidly during this period,showing the clear precursor characteristics of rockburst. Stress concentration at the the arch crown and dome of tunnel leads to the earliest failure,and cracks appear on account of the tensile stress at the side walls. Brittle failure of the surrounding rock begins with the particle ejection,then pieces peeling and cracks propagating,and the deformation and failure characteristics show certain amount of feature of rock burst.