客运专线双线隧道穿过软弱夹层力学效应研究

以贵广客专太阳庄隧道为背景,研究隧道穿越软弱夹层施工过程中围岩变形特性、塑性区及支护结构纵向、横向力学响应。洞周变形以竖向为主,软弱夹层洞周变形量远大于规范要求,应进行掌子面预加固,范围为前方10 m。支护结构沿纵向不均匀变形,拱顶纵向承受压应力,应加强地层变化处拱顶设计参数。支护仰拱沿纵向整体呈现拉应力,软弱夹层段沿纵向最大拉应力超过混凝土极限抗拉强度,且墙脚安全系数不满足规范要求,因此必须加强纵向、横向配筋率,对墙脚进行特殊处理。可预留充分的变形富裕值,实行"边让边抗",充分发挥围岩自承载能力,一次支护屈服后,再施作二次支护。研究成果对贵广客专太阳庄双线隧道施工具有重要指导意义,可为今后类似工程提供参考和借鉴。

Study on mechanical effect of double-tracked tunnel of passengerdedicated railway passing through weak rock sandwich

By taking Taiyangzhuang tunnel of Guiyang-Guangzhou high-speed passenger railway as the background,this paper studied the mechanical effect for two-lane tunnel passing through weak interlayer in order to investigate deformation property,plastic zone of surrounding rock,longitudinal and transverse mechanical response of support.The main deformation of tunnel is due to vertical settlement of vault and the deformation is much more than code requirement,which means pre-reinforcement technology for weak surrounding rock of tunnel should be adopted and the reinforcing scope is about 10 m ahead of working face.Inhomogeneous deformation of support takes place due to vault bearing vertical pressure along tunnel axis,which means vault design parameters should be strengthened at stratum changing zone.Invert is subjected to tensile stress along the longitudinal tunnel axis,maximum tensile stress for weak interlayer exceeds the ultimate tensile strength of concrete,and safety factor of wall footing does not meet the regulatory requirements,which indicates that longitudinal and transverse reinforcement ratio should be improved.Deformation reservation is carried out to play self-carrying capacity of rock fully.When the first supporting is yielded,secondary support is done following.The results of this paper can guide the construction of Taiyangzhuang tunnel on Guiyang-Guangzhou high-speed passenger railway and can also provide reference for similar projects in the future.