软弱破碎围岩隧道超前支护确定方法

Determination of advance supports in tunnel construction under unfavourable rock conditions

如何合理确定超前支护类型及参数范围是保证软弱破碎围岩隧道施工的关键问题。针对该问题,提出包含施工安全性评价、超前支护方式选择、超前支护参数确定3个方面的隧道超前支护确定方法。首先,对隧道围岩的变形预测值1S和控制标准值2S进行比较,判断是否需要采用超前支护措施;进而采用工程类比法初步确定可能采取的超前支护方式,对采用超前支护后的隧道围岩变形预测值3S与控制标准值2S进行比较,选择满足变形控制标准的超前支护方式;在此基础上,对超前支护参数的敏感性和加固有效性进行分析,并制定出支护参数的上限值和下限值。将该方法成功应用于贺街大断面高速铁路隧道施工中,弥补了以往经验设计方法的不足,为定量化确定隧道超前支护提供一种思路,对软弱破碎围岩条件下隧道安全施工的理论研究和工程实践具有一定指导意义。

Determining the types and parameters of advance support is an important work in tunnel construction under conditions of unfavourable rocks. In this research,the determination of advance support for tunnel was established,including the safety assessment of construction,the modes election and the parameter determination of advance support. The predicted deformation value1 S of surrounding rock of tunnel and the value2 S from control standard were compared to determine whether the advance support was required. The engineering analogy was used to determine the modes of advance support under the condition that the predicted deformation value 3S adopting the selected mode of advance support meets the control standard. The sensitivity and effectiveness of support parameters were analyzed to determine the upper and lower bounds of the support parameters. The method has been successfully applied in shallow covered Hejie high-speed railway tunnel.