新建隧道对上覆既有隧道受力变形解析

为了理解既有隧道在盾构下穿影响下的受力变形规律，提出一种既有隧道与土体相互作用解析方法。采用Loganathan解获得盾构下穿引起周围土体自由位移场；随后，将既有隧道假定成放置在Vlazov地基上的欧拉梁，考虑既有隧道两侧侧向土体作用，基于既有隧道边界条件及Taylor级数展开获得隧道变形响应解析解。通过与上海工程和离心机实测数据比较：该方法与实测数据较为接近，证明该方法的可靠性；与该方法退化解析解比较，该方法计算结果更符合实测数据，随后对相关参数进行分析。参数研究表明：随着新旧隧道竖向间距的增大，既有隧道受到盾构开挖的影响逐渐减小；增大地层损失率会引起既有隧道位移及弯矩线性增大；提高既有隧道抗弯刚度能够明显减小盾构开挖对既有隧道受力变形响应。

Analytical study of force and deflection of existing tunnel induced by new tunnel excavation underneath

To figure out the force and deflection laws of the existing tunnel under the influence of tunneling underlying. The surrounding soil-free deformation induced by tunneling underneath could be obtained by Loganathan solution, then to simplify the existing tunnel as Euler-Bernoulli beam resisting on Vlazov foundation and take the tunnel lateral soil action on both sides of existing tunnel into consideration, then theoretical results of the existing tunnel deflection response can be extracted based on the condition of tunnel boundary and Taylor series. Compared with the measurements of engineering project from Shanghai city and centrifuge test, the solution given by the proposed method solutions is closer, and in turn security of the proposed method can be verified. By comparing with degraded result, the calculation result from the proposed method has more in line with measured data, then the influence of related parameters can be analyzed. The results show that: with increasing the vertical distance between new and old tunnels, the affection of the existing tunnel induced by tunneling underlying will be reduced. Enlarging the volume loss will cause the tunnel deformation and the bending moment increases linearly. Increasing the bending rigidity of the existing tunnel will obviously reduce the force and deflection response of the existing tunnel caused by tunneling underlying.