中文摘要：

为了合理地分析基坑施工对下卧已建地铁隧道上抬变形的影响,首先,将软土地基考虑为三参量H-K黏–弹性体,推导了自由边界半无限黏–弹性空间体在内部集中荷载作用下的Mindlin时域解,并采用积分、叠加的方法,提出了一种用于计算基坑开挖及工程降水所引起的邻近隧道附加应力的方法;然后,将已建隧道视为Pasternak黏–弹性地基上的欧拉伯努利长梁,建立了隧道在附加荷载作用下的平衡微分方程,求得了隧道纵向附加变形和内力的表达式;最后,将所提方法运用于某近接既有地铁隧道的基坑工程中,并与三维数值模拟流变分析结果和现场实测结果进行了对比分析。研究发现：提出方法能较好地反映软土隧道变形随时间的发展趋势;隧道纵向附加变形、曲率和弯矩的解析解与数值解基本一致,且上抬变形的解析解与实测值能较好地吻合;成果可为基坑施工对邻近隧道的影响分析及保护措施的制定提供一定的理论依据。

英文摘要：

To predict the uplift deflection of subway tunnel due to adjacent excavation more reasonably, the soft soil foundation is considered to be a viscoelastic body with the constitutive relation of three-parameter H-K model at the first stage, and the Mindlin＇s time-domain solution of a semi-infinite viscoelastic body under internal concentrated load is derived. Furthermore, a calculation method is presented by integration and superposition to study the additional stress of a tunnel due to adjacent pit-excavation and dewatering, and the tunnel is assumed to be a long Euler-Bernoulli beam on a Pasternak-type viscoelastic foundation. The governing differential equation for the tunnel is formulated, and the analytical expressions for the deflection and internal force of the tunnel are deduced. Finally, the proposed method is used in a practical foundation pit which is adjacent to the exiting subway tunnels, and the analytical solution is compared with the results from 3-D rheological numerical simulation and in-situ measurement. It is found that the proposed method can reflect the development trend of tunnel deflection with time better. The longitudinal deflection, curvature and bending moment obtained by the analytical method are basically consistent with those from numerical simulation and in-situ measurement. The research results may provide a theoretical basis to study and protect the existing tunnels influenced by adjacent excavation.