浅埋大跨黄土隧道下穿公路方案比选

以大跨黄土隧道下穿公路安全施工为背景，对隧道下穿公路的安全施工方案进行研究。基于公路路面破损指数与下穿公路施工风险事件引起路面最大沉降之间的关系确定了隧道下穿施工可能引起的路面最大允许沉降量，并据此制定出施工管理基准，对比分析了CRD和CD法引起的隧道拱顶沉降、地表最大沉降、支护受力和隧道周边地层塑性区特征，建议采用CD法进行下穿施工。下穿孙辛路施工监测结果表明，采用CD法保证了隧道施工安全和孙辛路的正常通行。

Scheme Comparison and Selection of Large span Loess Tunnel Excavated Under Road

Taken excavation of large span loess tunnel under road as study background, the research of safety construction method has been carried out. Based on the relationship of pavement condition index(PCI) and the possible largest settlement of road induced by risk event of tunnel excavation, the settlement standard is achieved, according to which the construction management rules are established. The CD method is proposed to excavate the tunnel undercrosss the road on the basis of comparison analysis of tunnel crown settlement, road surface settlement, stress of support structure and characteristics of ground yielding zone around tunnel section. The settlement monitoring results during tunnel construction by CD method have shown that the proposed method can guarantee the safety of tunnel excavation underneath the road.