扁平偏压隧道浅埋段施工技术及可行性检验

Construction Technology and Feasibility Inspection of Flat Bias Tunnel Shallow Buried Section

该文以福建平潭某隧道工程为背景,分析洞口浅埋段在开挖过程中引起地表裂缝及衬砌裂缝的原因。针对隧道浅埋段受偏压影响较大的情况,提出采用微型钢管混凝土加固靠山体一侧,在远离山体一侧采用挡墙加固的联合处置技术。通过对加固前后监测结果的对比发现,加固后地表累积沉降值基本保持不变,无增大趋势;拱脚处的累积沉降基本保持不变,部分点在偏压减轻后沉降量随之减小;拱顶累积沉降基本保持不变,无增大趋势;收敛值绝大部分明显减小。结果表明,其加固措施能够有效地解决扁平特大断面隧道穿越洞口浅埋段施工过程中因偏压而开裂或坍塌的问题。

Taking a tunnel project in Pingtan of Fujian as the engineering background, the article analyzes the causes of surface crack and lining crack in the excavation process of the shallow buried section at the tunnel entrance. Aiming at the greater bias influence on the shallow buried section of tunnel, the article puts forward the joint disposal technology of using the micro concrete-filled steel pipe to reinforce a side of mountain and using the retaining wall to reinforce far from a side of mountain. According to the comparison of the monitoring results before and after reinforcements, the results show that the surface accumulated settlement value after reinforcement remains unchanged without the increasing trend, the accumulated settlement remains unchanged at the arch foot, the settlement amount decreases at the partial points with the bias decrement, the accumulated settlement remains unchanged at the arch top without the increasing trend, and the most of convergence value obviously decreases. The result shows that the reinforcing measures can efficiently solve the problems of cracking or collapse because of bias in the construction of the flat large sectional tunnel across the shallow buried section at the tunnel entrance.