高地温对隧道岩爆发生的影响性研究

Influence of high geotemperature on rockburst occurrence in tunnel

新建拉林铁路桑珠岭隧道高地应力、高地温隧道开挖过程中岩爆灾害突出。考虑开挖卸荷与温降共同耦合作用,对隧道开挖过程中不同温度时洞周应力释放过程进行数值模拟,同时对隧道开挖后的二次应力进行现场实测,就高地温对隧道洞周应力的影响进行了比较分析,最后就不同岩爆判据下高地温对岩爆发生的影响性进行了讨论。研究结果表明,采用应力释放率和温降指标反映开挖卸荷与温降共同耦合作用能合理描述高地应力高地温段开挖过程中的应力特征和岩爆发生规律。当温降超过55℃,应力释放率大于40%以后,σ_θ及σ_1量值随应力释放率增大而线性增长,当应力释放率达到100%时达到最大,不同位置洞周应力拱脚处增长最快,拱顶次之,其他位置较低。在开挖中受高地温影响岩爆发生时间提前,岩爆发生等级亦不断增加。

Due to the existence of high geostress and high geotemperature,the rockburst disaster is highly possible during the excavation of the newly-built Sangzhuling tunnel in the lasa-Nyingchi project.According to the unloading-temperature drop coupling action,the numerical model was conducted to simulate the stress release process during the tunnel excavation at different temperatures.At the same time,the secondary stress field was measured on site.The influence of high geotemperature on the circumferential stress was comparatively analyzed.Finally,the effect of high geotemperature on rockburst occurrence was discussed by considering different criteria.The results show that the indices of stress release rate and large temperature drop are used to reflect the excavation unloading-temperature drop coupling function,which can reasonably describe stress characteristics and rockburst occurrence law under high-geostress and high geotemperature in the excavation process.When the temperature drop exceeds 55℃and the stress release coefficient is greater than 40%,σθandσ1 linearly increase with the increase of stress release coefficient.Theσθandσ1 achieve maximum values when the stress release rate reaches 100%.It is found that the stress at the arch foot increases fastest,following at the vault.With the increase of the stress release coefficient,the rockburst occurs earlier due to the high geotemperature,and the grade of rock burst also increases.