地面出入式盾构法隧道施工引起的土体垂直变形

Soil vertical deformation induced by ground penetrating shield tunnel construction

对地面出入式盾构法隧道施工引起的土体垂直变形计算方法进行研究。考虑盾构轴线与水平面的夹角?(即隧道埋深变化),对林存刚公式进行修正,结合正面附加推力、盾壳摩擦力、附加注浆压力和土体损失的共同作用,提出全新的土体垂直变形计算公式。算例分析结果表明:在隧道埋深较浅工况下,新方法计算结果与林存刚公式的计算结果差异较大,新方法计算得到的开挖面前方地面隆起和后方地面沉降均较大;盾构上仰掘进时,随着?增大,由正面附加推力、盾壳摩擦力及土体损失引起的纵向土体垂直变形曲线呈上移趋势,由附加注浆压力引起的纵向土体垂直变形曲线则呈下移趋势;地面沉降最大值变小,但地面横向沉降槽范围逐渐变大。

This paper is to investigate the calculation methods for the soil vertical deformation induced by constructing the ground penetrating shield tunnel. Lin＇s formula was also corrected by considering the included angle ？ between the axis of the tunnel and the horizontal plane（namely the variation of the buried depth of tunnel）. A new formula of soil vertical deformation was derived by combining with bulkhead additive thrust, the friction force between shield and soil, additional grouting force and soil loss. Through analysing the examples, it was found that the results obtained from the new method were entirely different from those of Lin＇s formula in a shallowly embedded tunnel. Especially, the results of the ground uplift before the excavation face and the settlement after the excavation face were both larger by the new method. When the shield tunnel excavated upward with the increase of ？, an upwards trend could be seen from the vertical deformation curve of longitudinal soil, which was induced by bulkhead additive thrust, friction force and soil loss. While in the same situation, a downward trend was found from the deformation curve of soil, which was induced by additional grouting pressure. In addition, the maximum value of the surface settlement reduced, whereas the range of the transverse surface settlement trough increased.