隧道围岩变形的时空特性研究

隧道围岩变形时空特性是支护结构动态设计的基础依据,针对速度350 km/h高速铁路客运专线双线隧道,采用数值模拟方法研究隧道围岩变形的空间分布特点和演化规律,提出反映围岩变形时空效应的拱顶纵向变形曲线拟合公式。在自重应力场下,隧道拱底位移值最大,施工中应尽早施作仰拱结构;道床底面以上拱顶位置位移最大,与坍塌、冒顶事故密切相关,应作为工程现场监测的重点。掌子面对前方未开挖围岩约束效应显著,围岩变形空间分布较为均匀,非圆效应对掌子面后方围岩变形影响显著,各阶段围岩变形随时间的演化规律具有明显的自相似特征。通过拟合分析提出高速铁路隧道拱顶纵向变形曲线的计算公式,基于任意3种新工况与Vlachopoulos公式进行对比分析,证明了新提出的计算公式应用效果良好。

Study on Space-time Charateristics of Surrounding Rock Deformation in Tunnel Engineering

The space-time characteristics of the surrounding rock deformation are the basis for the dynamic design of the supporting structure.In this paper,for the double track tunnel of 350 km/h passenger-dedicated high-speed railway,,the numerical simulation method was used to study the spatial distribution characteristics and evolution law of the surrounding rock deformation.A fitting formula of the longitudinal deformation profile reflecting the space-time effect at the crown was proposed.Under the self-weight stress field,the heave at the bottom of the tunnel was the largest.entailing the completion of the inverted arch as soon as possible during construction.Above the bed plate,the radial displacement on the vault,which is closely related to the collapse and roof fall accidents,was the maximum,and which should be the focus of field monitoring in the tunnel engineering.The constraint effect of the face for the unexcavated surrounding rock was significant,with relatively uniform spatial distribution of the deformation of the surrounding rock.The non-circular effect had a significant effect on the surrounding rock deformation behind the face.The evolution law of the surrounding rock deformation with time at each stage had obvious self-similar characteristics.The calculation formula of the longitudinal deformation curve of the tunnel vault was proposed through fitting analysis.Based on any three kinds of working conditions and the comparison analysis with the Vlachopoulos formula,it proves that the formula in this paper has a good application effect.