土岩复合地层隧道群洞施工力学响应研究

为探究小净距隧道群洞穿越不同地层施工引起的力学响应,基于青岛地区土岩复合地层特殊地质条件,通过数值计算并结合现场测试数据,分析小净距地铁隧道群洞施工引起的地表沉降、应力特征、拱顶变形规律。结合工程实际,将隧道群洞施工划分为4个不同阶段并依此分析,结果表明:隧道群在其阶段Ⅳ施工后引起地表沉降变形较大,其他阶段地表沉降无明显变化;不同开挖阶段对夹岩的扰动程度存在差异,阶段Ⅳ施工使夹岩主应力出现剧烈变化,且夹岩最薄弱处最不利状态发生于阶段Ⅳ,但无剪切破坏现象;隧道拱顶沉降最大增量在该条隧道开挖后出现,上线隧道施工显著影响其他隧道拱顶沉降,且能够引起中线隧道拱顶抬升。研究成果为同类工程的施工稳定性分析提供了现场指导和技术支持。

Study on Mechanics Response to Tunnel Group Construction in Soil-rock Compound Stratum

To explore the mechanical response caused the construction of small clear distance tunnel group passing through different stratums,numerical calculation and field test data,stress characteristics and surface settlement and vault deformation caused by construction of small clear distance tunnel group are analyzed based on soil-rock compound stratum of special geological conditions in Qingdao. In combination with the practical engineering,the construction of tunnel group is divided into four different phases. The results show that the surface subsidence is bigger in phase IV and no obvious changes in other phases; the construction of phase IV makes drastic changes in interlaid rock principal stress,the most unfavorable condition of interlaid rock occurs in phase IV without shear failure; the biggest incremental subsidence of tunnel vault appears after tunnel excavation; the upper line tunnel construction significantly affects the vault subsidence of other tunnels and may give rise to midline tunnel vault uplift.The research results provide guidance and technical support to the engineering stability analysis of similar projects.