论文部分内容阅读
基于隧道开挖椭圆化变形模式,针对盾构施工分别考虑气压效应与无气压效应2种工况,提出饱和土中浅埋隧道开挖引起的地层长、短期变形和隧道衬砌内力位移的计算方法。结果表明:椭圆化变形模式下得到的位移曲线与实测值吻合较好,考虑气压效应条件下隧道开挖施工引起的土体变形大于非气压工况,长期影响解大于短期影响解。通过参数调整研究衬砌洞周处位移分布规律时,发现衬砌径向负位移在90°拱顶处达到最大值,在270°拱底处取得最小值,反映了衬砌明显的椭圆化和整体下沉变形趋势,并且随着半径增大以及土体模量减小,椭圆化变形趋势越明显;切向位移值基本以90°/270°隧道中轴线为分界轴,正值取在隧道左半圆,负值取在隧道右半圆,增大半径以及减小土体模量提高了切向位移值的整体水平。通过参数调整研究衬砌内力分布规律时,发现硬土质和大间隙时隧道轴力更容易表现出明显的椭圆化分布趋势,弯矩值随着隧道埋深、隧道半径以及土体重度减小而减小,随着土体侧压力系数k的减小而增大。盾构气压水平的提升,使衬砌轴力受压区范围增幅明显,并使衬砌的正、负弯矩值均增大。分析成果可为正确预估复杂工况下盾构开挖变形提供一定的理论依据。
Based on the oval deformation mode of tunnel excavation, considering the two conditions of atmospheric pressure effect and non-atmospheric pressure effect in shield tunnel construction, this paper puts forward the calculation method of formation long-term deformation, short-term deformation and tunnel lining internal force displacement caused by shallow excavation in saturated soil . The results show that the displacement curve obtained in the elliptical deformation mode is in good agreement with the measured value. The soil deformation caused by tunnel excavation under the pressure effect is greater than that under non-atmospheric pressure. The long-term influence solution is larger than the short-term solution. Through the parameter adjustment study of the displacement distribution law at the lining of a tunnel, it is found that the radial negative displacement of the lining reaches the maximum value at the 90 ° vault and the minimum value at the 270 ° arch bottom, which reflects the obvious ovalization and overall sinking The trend of elliptical deformation is more obvious with the increase of radius and the decrease of soil modulus. The tangential displacement is basically based on the central axis of 90 ° / 270 ° tunnel and the positive value is taken in the left half of the tunnel, The negative value is taken in the right half of the tunnel. Increasing the radius and decreasing the soil modulus increase the overall level of the tangential displacement value. When adjusting the law of lining internal force distribution through parameter adjustment, it is found that the tunnel axial force is more likely to show the elliptical distribution trend when the soil and the large clearance are large. The bending moment decreases with the depth of the tunnel, the radius of the tunnel and the decrease of the soil mass Small, with the soil side pressure coefficient k increases. With the increase of shield gas pressure level, the range of bearing axial pressure force increases obviously, and the positive and negative bending moment of lining increase. The results of the analysis can provide a theoretical basis for correctly estimating the deformation of shield tunneling under complex conditions.