中文摘要：

地下工程近接施工影响最本质的原因是由于新建工程的施工引起围岩应力状态再次重分布,从而导致一系列的力学行为变化。文章引入强度折减法,通过数值模拟手段,对新建隧道近接既有建筑物施工的破坏模式进行了研究。研究结果表明：当新建隧道与既有建筑距离较远时,仅是隧道本身的单独失稳,不会波及建筑物;当两者距离较近时,夹岩破坏。在此基础上,根据破坏模式的差异提出两者有无近接施工影响的若干判据如下：（1）在隧道埋深不变（0°方向）的情况下,基于强度折减法的安全系数趋于定值可作为新建隧道施工对既有建筑物有无影响的判据;在隧道埋深变化（非0°方向）的情况下,安全系数达到峰值即可作为上述判据;（2）基于剪切应变增量显示的滑移带是否贯穿隧道与建筑物加载面之间的夹岩,可作为新建隧道施工对既有建筑物有无影响的形象直观判据。研究成果可为控制此类近接工程的安全风险提供理论基础,也为进一步建立影响分区、制定相关规范指南提供理论支撑。

英文摘要：

The primary impact of construction of a new tunnel adjacent to an existing building is the redistribution of surrounding rock stress, which results in variations to a series of mechanical behaviors. This paper introduces the strength reduction method and the numerical simulation for studying the failure modes during the construction of a new tunnel approaching existing buildings. The results indicate that when the new tunnel is far from the existing buildings, the instability affects only the tunnel itself, not the buildings; however, when the new tunnel is adjacent to the buildings, the rock sandwiched between them is damaged. Based on the different failure modes, the following criteria are presented for judging whether or not the new tunnel construction influences the existing buildings： 1） If the tunnel depth is fixed （namely at a direction of 0°）, and when the safety factor obtained by the strength reduction method is tending to be constant, then it can be used as a criterion regarding the inluenee. If the tunnel depth is varied （namely not at a direction of 0°）, the safety factor can be used as a criterion only when it reaches the peak; 2） Whether or not the slip band indicated by the shear strain increment goes through the sandwiched rock between the tunnel and buildings, it can be regard as the intuitive criterion regarding the influence. The research findings provide a theoretical foundation for managing the safety risk, studying the influence zoning and establishing corresponding standards and specifications in the future.