黄土隧道围岩局部浸水静力特征分析

Statics Analysis of Local Immersed Surrounding Rock in Loess Tunnel

中国西北地区湿陷性黄土分布广泛,由于其具有孔隙大、强度低等性质,导致黄土隧道修建时面临极大的困难与挑战。为了深入研究黄土隧道围岩局部浸水后对隧道结构稳定性的影响,依托定西锦屏隧道,借助Midas/GTS建立隧道模型,分别针对正常开挖和局部浸水两种工况进行对比分析。研究局部浸水后黄土隧道围岩和衬砌结构的变形规律和力学特征。结果显示:正常开挖与浸水后,围岩最大沉降值均出现在隧道拱顶,开挖后最大沉降值为9.60 mm,局部浸水后围岩最大沉降量增大到13.18 mm;正常开挖后围岩最大主应力为59 kPa,浸水后,围岩最大主应力出现在拱顶与仰拱处,最大值为89 kPa。黄土隧道围岩局部浸水后,衬砌结构的最大压应力为5.06 MPa,最大拉应力为2.08 MPa。最大压应力为设计强度的42%,最大拉应力超过抗拉设计强度。

Collapsible loess is widely distributed in northwest China.Due to its large porosity and low strength,the construction of loess tunnel faces great difficulties and challenges.In order to investigate the effects of local water immersion in loess tunnel surrounding rock on tunnel structural stability,relying on the Jinping Tunnelin Dingxi,the tunnel model was established with the help of Midas/GTS.The comparison and analysis of normal excavation and local flooding were carried out respectively.The deformation rules and mechanical characteristics of surrounding rock and lining structure of loess tunnel after local flooding were studied.The results show that after normal excavation and water immersion,the maximum settlement value of surrounding rock appears in the tunnel arch,and the maximum settlement value after excavation is 9.60 mm,and the maximum settlement value increases to 13.18 mm after local water immersion.After normal excavation,the maximum principal stress of surrounding rock is 59 kPa.After water immersion,the maximum principal stress of surrounding rock appears at the arch and invert,and the maximum value is 89 kPa.The maximum compressive stress and the maximum tensile stress of the lining structure are 5.06 MPa and 2.08 MPa after the surrounding rock of the loess tunnel is partially flooded.The maximum compressive stress is 42% of the design strength,and the maximum tensile stress exceeds the design tensile strength.