双层顶管隧道施工引起的土体竖向变形规律研究

采用数值分析方法,研究了双层顶管隧道施工引起的土体竖向变形规律。研究表明:顶管隧道施工引起的地层移动主要是由于地层损失引起的。地层移动主要是垂向位移,其水平位移很小,可忽略不计。在垂直顶管走向上,地面沉降呈以顶管轴线为对称轴且开口向上的抛物线形状,其最大值发生在顶管正上方。在顶管施工过程中,先行施工的下层顶管引起的沉降约占总沉降量的80%;当上层顶管位置不变时,总沉降量随着下层顶管埋深的增大而线性增大;当顶管间距逐渐增大时,上层顶管开挖引起的沉降量与总沉降量之比逐渐减小,下层顶管引起的沉降量与总沉降量之比逐渐增大,下层顶管对上层顶管影响逐渐减弱。

Research on Varying Regularity of Soil Vertical Deformation Caused by the Construction of Two-layer jacking-pipe

With the use of numerical methods,the varying pattern of soil vertical deformation and influence factors are researched when the tunnel is being excavated. The research shows that the soil sedimentation is mainly caused by the stratum loss. The vertical displacement is the major section of the stratum movement. The magnitude of the horizontal direction is infinitesimally small, which can be ignored. On the vertical axis of the jacking-pipe, the area with a big uplifted quantity of soil presents an opening up parabolic distribution and the uplifted quantity of soil near the low position of the pipe-jacking ranks the top. 80% of the sedimentation is caused by the underlying pipe jacking. When the location of the upper jacking-pipe remains the same, the total settlement increases with the rise of the burial depth of the underlying jacking-pipe linearly. The settlement proportion of the upper jacking-pipe settlement and the total settlement decreases with the rise of the burial depth of the underlying jacking-pipe gradually and the proportion of the underlying jacking-pipe settlement and the total settlement increases with the rise of the burial depth of the underlying jacking-pipe gradually.