复杂应力环境中隧道大变形特征与形变控制

Large deformation characteristics and deformation control of tunnel in complex stress environment

以丽香铁路中义隧道3#横洞工区为工程背景,通过现场变形监测分析不同断面形式下的平导与正洞大变形特征,研究发现存在片理的变质玄武岩隧道在极高地应力环境下挤压大变形特征明显,水平收敛为洞周收敛的主要变形。通过数值模拟验证隧道断面优化与支护补强措施的有效性,结果显示:减小隧道断面曲率突变和使隧道断面对称能够减小隧道围岩变形量,增设锁脚锚杆与增大钢筋网强度均能有效控制隧道形变,共同作用下可控制超过65﹪的隧道围岩变形量,缩减大变形段围岩塑性区分布,对中义隧道的大变形有很好的控制作用,可为复杂应力环境下铁路隧道施工提供指导.

Taking the work area of 3#Transverse Gallery of Zhongyi Tunnel of Lijiang-Shangrila Railway as the engi-neering background,the large deformation characteristics of parallel adit and main tunnel under different section forms were analyzed by field deformation monitoring.It was found that the large deformation characteristics of metamorphic basalt tunnel with schistosity were obvious under extremely high ground stress environment,and the horizontal conver-gence was the main deformation around the tunnel.The effectiveness of tunnel section optimization and support rein-forcement measures was verified by numerical simulation verification.The results showed that the deformation of tunnel surrounding rock could be reduced by reducing the sudden curvature change of tunnel section and making the tunnel sec-tion symmetrical,adding foot-lock anchor bolts and increasing the strength of steel mesh could effectively control tunnel deformation.Under the joint action,more than 65%of the deformation of tunnel surrounding rock could be controlled,reducing the distribution of plastic zones in the large deformation section of the surrounding rock.These measures had a good control effect on the large deformation of the Zhongyi Tunnel which could provide guidance for railway tunnel con-struction in complex stress environment.