秦巴山区某软岩公路隧道合理施工方法研究

Reasonable methods of constructing highway soft-rock tunnel in Qinba mountains

以秦巴山区某软岩公路隧道为工程背景,采用FLAC数值模拟和现场监测相结合的方法对该隧道合理施工方法进行了研究。建立3种不同施工方法下的计算模型,数值计算结果显示,相比于台阶法施工和单侧导坑法,采用留核心土法施工引起的隧道围岩变形较小,能够满足设计要求,从经济和施工工期角度来看,留核心土法是该地区软岩隧道最为合理的施工方法。为了验证数值计算结果的可行性,在隧道周围设置了变形监测点,实测结果表明,采用留核心土法施工后,隧道最大周边收敛14.81 mm,最大拱顶沉降值为27.11 mm,隧道变形在允许范围之内。隧道围岩变形的实测值与预测值变化趋势基本一致,表明FLAC数值模拟可在隧道施工前对隧道施工方法的合理性做出评价,具有超前指导意义。

Taking the background of a highway soft-rock tunnel in Qinba mountainous,with the means of FLAC numerical simulation and site monitoring, the reasonable method of constructing a highway softrock tunnel in Qinba mountainous was researched. Three different construction ways were put forward. Compared with the step method and Single Side Heading Method, the result of numerical simulation showed that the core soil-retained construction method could lead the surrounding rock deformation to be little and met the construction requirement. From the view of economic and construction period, the core soil-retained was the best construction method for the soft rock tunnel excavation. Depended on the site measurement, after taking the core soil-retained construction method, the feasibility of numerical simula- tion result was verified. The result of site measurement indicated that the maximum peripheral convergence was 14.81 mm and the maximum crown settlement was 27. 11 mm. So,the tunnel deformation was in the permissible range. Besides, the measured values trend of surrounding rock deformation was similar to the predictive value,which indicated that the the FLAC could serve as a evaluation method to verify the reasonableness of construction method before construction, which had advanced guiding significance.