铁路隧道下穿既有公路地层变形特性研究

文章结合张唐铁路工程燕山隧道下穿公路出口段,采用三维有限差分程序,研究分析了其施工过程中的地层变形特性、力学响应、能量积聚及塑性区分布特征.研究结果表明:公路最大沉降量小于规范要求,围岩竖向最大变形为20 mm,水平变形为16 mm;掌子面前方挤出变形明显,最大值为38 mm;边墙能量密度集中现象较显著,位于距洞壁5 m深部围岩处；掌子面前方6 m左右围岩处出现能量积聚,为掌子面稳定关键部位:塑性区主要集中在掌子面前方、拱肩、边墙及墙脚.为此,建议对掌子面进行预加固,保证墙脚和拱肩部位配筋,提高结构整体稳定性.

Study on Characteristics of Stratum Deformation Induced by Railway Tunnel Underpassing Existing Highway

Based on the Yanshan tunnel underpassing highway on Zhangjiakou-Tangshan railway,it analyzes the characteristics of stratum deformation,mechanical response,energy accumulation and distribution of plastic zone during construction by three-dimensional finite difference.The results indicate: the maximum settlement of highway is less than that specified in specifications,the maximum vertical deformation of surrounding rock is 20 mm and it is 16 mm for the horizontal deformation,the extruded deformation in front of the working face is large with the max.value of 38 mm,it is obvious for the energy density concentration of side wall where is 5m away from the tunnel wall,energy accumulation occurs at the surrounding rock 6m ahead of working face,plastic zones predominantly are located at the front,shoulder,sidewall and foot.Therefore it is suggested the working face be reinforced to guarantee the reinforcement of tunnel foot and shoulder to improve the structure stability.