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以中国西南地区地质作用最复杂的高黎贡山越岭隧道为例,在隧道工程地质条件分析的基础上,对最可能发生岩爆的花岗斑岩进行真三轴岩石力学试验测试,并结合原位地应力测量结果,确定不同工况下岩爆模拟试验的三向应力量值和加载、卸载方式。岩爆模拟试验结果表明,单纯卸载和卸载–加载方式都可以出现岩爆,但卸载–加载方式的岩爆明显比单一卸载方式的岩爆要强烈,说明隧道开挖后二次应力分布引起的应力集中对岩爆的发生起着十分重要的作用。岩爆破坏过程通常具有渐进性,一般先在试件表面出现岩屑剥落,有时伴有裂纹的扩展,最后才会发生岩块的弹射现象。绝大多数试件岩爆具有明显的滞后性,表现为加载或卸载一段时间后才发生岩爆;而岩爆过程持续时间却非常短(1 s左右),具有明显的瞬时性。声发射监测结果显示,花岗斑岩在外部荷载作用下声发射强烈,对岩爆具有较好的前兆性。上述模拟结果和认识对于地质条件复杂的造山带深埋隧道工程建设具有重要的参考价值。
Taking the most complicated Geoligong Mountain Tunnel in Southwest China as an example, based on the analysis of tunnel geological conditions, the true triaxial rock mechanics test is carried out on the granite porphyry that is most likely to rock burst In situ stress measurement results to determine the different conditions rockburst simulation test three-way stress value and loading and unloading methods. The results of rockburst simulation show that the rockburst can occur only in the unloading and unloading-loading modes, but the rockburst of the unloading-loading mode is obviously stronger than that of the single unloading mode, which indicates that the secondary stress distribution in tunnel after excavation Stress concentration plays a very important role in rock burst. The process of rockburst destruction is usually gradual. In general, rock chip spalling occurs on the surface of the specimen first, and crack propagation sometimes accompanies it. Eventually rock ejection occurs. The rockburst of the vast majority of specimens has obvious hysteresis, which shows that rockburst occurs only after loading or unloading for some time, while the duration of rockburst is very short (about 1 s) with obvious instantaneous. Acoustic emission monitoring results show that the granite porphyry has strong acoustic emission under the external load and has good precursor to rock burst. The above simulation results and understanding are of important reference value for the construction of deep buried tunnels with orogenic belts with complex geological conditions.