高地应力水平岩层隧道滞后型岩爆时空倾向性机制分析

Mechanism Analysis of Time-space Tendentiousness of Delayed Rockburst in Horizontal Rock Tunnel with High In-situ Stress

浙江杭温水平岩层隧道内滞后型岩爆频发,但目前对于其孕育机理和时空倾向性研究不足。故采用有限差分软件,通过地应力测试和统计现场岩爆资料的方法,研究分析滞后型岩爆时空特征机制。结果表明:①滞后型岩爆具有明显的时空倾向性特征。近70%的滞后型岩爆时间上发生在该区开挖6~30 d,空间上滞后于掌子面30~100 m之间;且多发生中等岩爆,岩爆等级及可能性随时空变化呈现倒“V”形趋势。②硬岩在高地应力环境中具有明显的延性与时效变形特征;在卸荷条件下,应力释放率的逐渐增加是诱发滞后型岩爆的最主要因素。③开挖一定距离后,隧道周边不同位置处都出现应变能突变,且保持较高的应变能密度,易发生等级较高的岩爆。上述结果为以后预测滞后型岩爆和施加相应支护措施提供了依据。

Delayed rockburst occurred frequently in HangWen Railway’s horizontal rock tunnel in Zhejiang Province,but there are few studies on its gestation mechanism and space-time tendentiousness.Therefore,taking the time-dependent deformation of tunnel surrounding rock induced delayed rockburst as the core,the characteristics and mechanism of delayed rockburst were studied and analyzed by means of in-situ stress test and statistical field rockburst data.The results show these as follows.Delayed rockburst has obvious time-space tendentiousness characteristics.Nearly 70%of the delayed rockburst occur in the excavation of 6~30 days in this area,and lag the palm faces of 30~100 m in space.The delayed rockburst mostly occurs in medium rockburst,and the rockburst grade and possibility show an inverted“V”trend with time and space.Hard rock has obvious ductility and time-dependent deformation characteristics in high in-situ stress environment.Under unloading conditions,the stress releasing rate is the most important factor inducing delayed rockburst.After a certain distance of excavation,strain energy mutations occur at different locations around the tunnel,and a high strain energy density is maintained,which is prone to high-level rock burst.The above results provide a basis for predicting delayed rockburst and applying corresponding supporting measures in the future.