川藏铁路巴玉隧道开挖二次应力分布特征与岩爆风险分析  

Secondary Stress Distribution Characteristics and Rockburst Risk Analysis of Bayu Tunnel in Sichuan-Tibet Railway

作　　者：吴春成 WU Chuncheng(China Railway Qinghai-Tibet Group Co.,Ltd,Xining 810007,China)

机构地区：[1]中国铁路青藏集团有限公司,西宁810007

出　　处：《铁道标准设计》2021年第7期131-135,142,共6页Railway Standard Design

基　　金：中国铁路总公司科技研究开发计划项目(2017G006-B)。

摘　　要：川藏铁路巴玉隧道施工中岩爆灾害突出,有必要分析该隧道施工过程的岩爆风险。采用数值模拟研究巴玉隧道开挖二次应力分布和损伤特征,基于Hoek判据评估开挖过程中的岩爆风险,分析隧道平行错开掘进对岩爆风险的影响。结果表明:数值模拟的塑性区与声波测试的损伤区结果较为一致;隧道开挖后最大主应力分布于拱顶与拱肩,具有强烈岩爆风险。边墙发生应力卸载,多表现为拉剪破坏的剥落与片帮;相比独头掘进,超前开挖平导降低了正洞即时型岩爆风险。但正洞与平导间出现的“马鞍形”应力升高区,引起平导边墙的破坏,甚至诱发平导时滞型岩爆。巴玉隧道大部分岩爆发生于拱顶和拱肩,与评估结果较为一致,边墙发生了岩板弯曲鼓折和岩片剥落。研究结论为深埋硬岩隧道的岩爆灾害分析预测和防控提供参考。As the rockburst hazard is prominent in the construction of Bayu tunnel on Sichuan-Tibet Railway, it is necessary to analyze the rockburst risk. In this paper, numerical simulation is used to study the secondary stress distribution and damage characteristics of Bayu Tunnel. Based on Hoek Criterion, rockburst risk during excavation process is evaluated, and the influence of parallel-stagger excavating on the rockburst is analyzed. The results show that the plastic zone of numerical simulation is consistent with the damage zone using acoustic testing. After tunnel excavation, the maximum principal stress is distributed in the vault and spandrel with intense rockburst risk. The stress unloading of side wall is mainly manifested as spalling of tension shear failure. Compared with single heading excavation, the parallel pilot’s advanced excavation can effectively reduce the immediate rockburst risk at main tunnel. However, the"saddle shaped" stress rise zone between the main tunnel and the parallel pilot may cause the failure at the side wall of the parallel pilot, and even induce time-delayed rockburst. Most of the rockburst occur at the vault and spandrel in Bayu Tunnel, which is consistent with the evaluation results. The bending and bulging of rock plate and spalling of rock slice exist at the side wall. The research provides some references for the analysis, prediction and mitigation of rockburst disaster in deep hard rock tunnels.

关 键 词：铁路隧道 岩爆风险 开挖二次应力 平行错开掘进 Hoek判据 

分 类 号：U451[建筑科学—桥梁与隧道工程] U459.1[交通运输工程—道路与铁道工程]