盾构侧穿邻近古建筑的施工影响分析及保护措施加固效果的研究

Influences of construction of side-crossing shield tunnel on adjacent ancient architectures and reinforcement effect of protection measures

结合上海地铁11号线侧穿古建筑的实际工程,采用数值计算和现场实测相结合的方法,对国内最新型的MJS桩基施工预加固与新建隧道侧穿引起的邻近古建筑的沉降进行了深入研究。整个施工力学的全过程对建筑物的影响分为桩基施工扰动阶段、上行线穿越阶段和下行线穿越阶段3个阶段。其中先期桩基施工扰动的影响相对显著,但由于MJS桩的保护作用,上行线穿越影响次之,下行线穿越影响最小。计算结果表明,由于桩基施工的预加固与隧道左侧建筑物的存在,使得地表的沉降槽与传统的形式有较大区别;同时,地表的水平位移分布规律也发生了明显的变化。此外,由于隔离桩的保护,大大减少了盾构掘进对地表以及建筑物沉降的影响。现场监测与数值计算的结果对比分析也表明两者所反映的规律较一致,其数值差别较小,进而验证了数值计算方法的准确性与合理性。

Based on the side-crossing construction of Shanghai Metro line No. 11 close to the ancient architectures, numerical simulation and field monitoring are employed to study the settlement of the adjacent ancient architectures induced by the construction of MJS piles and the side-crossing of newly shield-driven tunnel. The influences on the buildings during the whole construction process can be divided into three stages： disturbance of pre-reinforced piles and crossing of up and down lines. The stage of pre-construction of MJS piles has the most remarkable impact. Due to the protection of MJS piles, the stages of crossing of up and down lines have the second largest and the smallest impacts, respectively. In addition, because of the construction of piles and the existing buildings at the left side of the tunnel, the settlement trough differs from the traditional one, and the distribution of horizontal displacement obviously changes. Moreover, due to the protection of isolation piles, the settlement produced by shield driving greatly decreases. Finally, the field monitoring data agree with the numerical results. The accuracy and rationality of the numerical simulation method is validated.