风化花岗岩隧道三台阶七步法快速安全施工工艺

Fast and Safe Construction Technology of Three Bench and Seven Steps Method of Weathered Granite Tunnel

风化花岗岩隧道建设具有施工难度大的特点,三台阶七步法在传统台阶法的基础上,优势更加突出。为提高风化花岗岩隧道的施工稳定性,对风化花岗岩隧道三台阶七步法快速安全施工工艺展开研究。以海螺峪隧道工程为例,结合衬砌结构受力情况,设计隧道内轮廓尺寸及支护结构,获取恒定轴向应力作用影响下的围岩轴向应变作用参数,计算隧道周边风化花岗岩围岩压力,为了避免锚固端整体滑移,调整开挖进尺及台阶长度,布置快速安全施工监控测量环境,利用邻近的收敛计收集现场数据。根据工程实例分析结果,当上台阶高度为4~5 m时,各项数值都保持在稳定状态,有利于施工稳定。

The construction of weathered granite tunnel has the characteristics of great construction difficulty,and the advantages of the three bench and sevenstep method are more prominent on the basis of the traditional step method.In order to improve the construction stability of weathered granite tunnel,the rapid and safe construction technology of three bench and sevenstep method of weathered granite tunnel is studied.Take the Conch Valley Tunnel project as an example,combined with the stress of the lining structure,design the contour size and supporting structure in the tunnel,obtain the surrounding rock axial strain parameters under the influence of constant axial stress,calculate the weathered granite surrounding rock pressure around the tunnel,in order to avoid the overall sliding,adjust the excavation footage and step length,monitor the rapid safety construction environment,and collect field data.According to the analysis results of the engineering examples,when the height of the upper bench is 4~5 m,all the values are kept in a stable state,which is conducive to the stability of the construction.