Simulation experimental investigation on rockburst of dolomite specimens at great depth tunnels
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摘要: 基于深埋隧道開挖工程的高應力條件及構造應力發育特征,利用深部巖爆實驗系統,模擬了兩種構造應力條件下白云巖的巖爆過程:三向應力作用下板狀試件瞬間卸載一個方向應力,保持其他兩向應力不變或保持其中一向應力,增加另一向應力.實驗獲得了應力-時間、應力-應變、聲發射特征及巖爆破壞規律.研究表明:本工程區內構造應力引發白云巖巖爆的可能性較大,巖爆臨界深度為290m.豎向構造應力引發的巖爆表現為局部片狀崩落,從卸載后發生時間看屬于滯后巖爆;水平構造應力引發的巖爆強度更高,表現為塊狀彈射后整體破碎,屬于瞬時巖爆.聲發射峰值均出現在巖石裂隙發育段,而密集度最高值對應巖石破裂段.聲發射峰值處的最大主應力約為巖石破裂時最大主應力的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.
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Key words:
- rock mechanics /
- rockburst /
- acoustic emission /
- deep tunnel /
- dolomite
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