深埋软岩隧道开挖及支护变形特征研究

针对滇中引水工程中磨盘山隧道的深埋软岩段,利用ANSYS建立三维数值模型,通过FLAC~(3D)进行计算,研究了深埋软岩隧道开挖及支护后围岩的变形和破坏特征。结果表明,围岩强度和隧道埋深是影响隧道变形破坏的重要因素。隧道开挖后,应力重分布,隧道前段围岩强度较小,变形总位移、塑性区范围大于后段,在拱腰两侧对称形成两个应力集中区。隧道支护后,有效限制了隧道变形的继续发展,各部位总位移值减小,塑性区范围也得到抑制,拱腰两侧应力集中区向洞壁靠拢,应力分布也变得均匀。

Research on Deformation Characteristics of Deep Soft Rock Tunnel after Excavation and Support

In order to explore and compare the deformation and failure characteristics of surrounding rock after excavation and support of deep soft rock tunnel for late tunnel construction, three-dimensional numerical model is established by ANSYS, and calculated by FLAC3D by taking the deep soft rock section in Mopan Mountain tunnel of water diversion project in the central Yunnan Province as a typical case. The results show that the strength of surrounding rock and the depth of tunnel are the important factors to influence the deformation and failure of the tunnel. After the tunnel excavation, the results of stress redistribution are that the surrounding rock strength is small, the total displacement of the deformation is bigger than the posterior segment, the plastic zone is larger than the posterior segment, and two stress concentration areas are symmetrically formed on the two sides of the arch waist. After the tunnel support, the development of the tunnel deformation is limited effectively; the total displacement of various tunnel parts decreases, the plastic zone is smaller, the stress concentration areas on both sides of arch waist is closer to wall, stress distribution becomes uniform.