拉林铁路板块缝合带岩爆隧道数值计算分析

Analysis on Rock-burst of the Tunnel in Plate Suture Zone of Lhasa-Nyingchi Railway by Numerical Simulation

岩爆是高地应力隧道工程建设中典型地质灾害之一,但针对板块缝合带这种以构造应力为主导的特殊地段隧道岩爆问题尚缺乏系统地研究。本文针对拉林铁路板块缝合带高地应力现状,采用数值模拟手段,以强度应力比法中最大主应力为标准,对隧道岩爆的控制措施,如应力释放孔布置、开挖进尺、初支和锚杆参数等不同工况下的围岩最大主应力进行了探究,研究得出:(1)应力释放孔对最大主应力控制效果可达5%~17%;且孔位布置应靠近开挖轮廓线,以斜向外插设置为宜;(2)开挖进尺对最大主应力影响不大,降幅小于1.2%;(3)其余两种措施最大主应力降低值居于上述两种措施之间。并结合现场防治措施,提出了板块缝合带地区岩爆隧道的控制措施建议。

Rock-burst is one of the typical geological hazards in the construction of tunnels in high ground stress filed.But there aren’t systematic researches on rock-burst in plate suture zone which the tectonic stress has dominant influence.In this paper,aiming at the current situation of high ground stress in plate suture zone of Lhasa-Nyingchi Railway,and taking the maximum principal stress in the strength stress ratio method as the criterion,the relationship between the parameters of control measures in rock-burst field such as the stress releasing holes;excavated length and primary support of tunnel and the maximum compressive stress of surrounding rock has been put forward by numerical stimulation.And the main contributions include:(1)The stress releasing holes can reduce the maximum principal stress by up to 5%~17%and it should be close to the excavation contour,and inserted in oblique outward direction.(2)The association between excavated length and the declining contents of the maximum compressive stress is not obvious and it is less than 1.2%.(3)The declining contents of the other two measures is in the middle.Combined with the control measures in practical engineering,the suggestions of control measures in plate suture zone are put forward.