深埋隧道白云岩试样岩爆模拟实验研究
Simulation experimental investigation on rockburst of dolomite specimens at great depth tunnels
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摘要: 基于深埋隧道开挖工程的高应力条件及构造应力发育特征,利用深部岩爆实验系统,模拟了两种构造应力条件下白云岩的岩爆过程:三向应力作用下板状试件瞬间卸载一个方向应力,保持其他两向应力不变或保持其中一向应力,增加另一向应力.实验获得了应力-时间、应力-应变、声发射特征及岩爆破坏规律.研究表明:本工程区内构造应力引发白云岩岩爆的可能性较大,岩爆临界深度为290m.竖向构造应力引发的岩爆表现为局部片状崩落,从卸载后发生时间看属于滞后岩爆;水平构造应力引发的岩爆强度更高,表现为块状弹射后整体破碎,属于瞬时岩爆.声发射峰值均出现在岩石裂隙发育段,而密集度最高值对应岩石破裂段.声发射峰值处的最大主应力约为岩石破裂时最大主应力的77.4%.Abstract: Based on the high-stress condition and the development characteristic of tectonic stress in excavating deep buried tunnels, the rockburst process of dolomite was simulated with a deep rockburst experimental system in two kinds of tectonic stress conditions:instantaneously unloading the minimum principal stress on a rectangle specimen, keeping others unchanged or maintaining the intermediate principal stress and increasing the maximum principal stress. The stress-time curve, the stress-strain curve, the acoustic emission characteristic and the rockburst law were tested. The results show that the possibility of dolomite rockburst caused by tectonic stress in the project area is striking. The critical depth of rockburst is 290 m. Rockburst caused by vertical tectonic stress shows partial sheet avalanche, belongs to lag rockburst. The intensity of rockburst caused by horizontal tectonic stress is stronger, shows massive ejection and overall fragmentation, and belongs to instantaneous rockburst. The acoustic emission (AE) peak presents in the crevice growth section, and the highest value of AE density occurs in the rock rupture segment. The maximum principal stress corresponding to the AE peak is 77.4% of that corresponding to the rock breakdown stage.