南京地铁区间盾构隧道“下穿”玄武湖公路隧道施工的关键技术研究

Research on key technique of shield tunnel construction beneath adjacent existing highway tunnel

针对南京地铁区间盾构隧道“下穿”玄武湖公路隧道的超近接施工力学行为,进行了三维有限元数值模拟研究。研究结果表明,对于玄武湖隧道这种“卸荷”型地下建筑物,在其下方修筑盾构隧道时不宜采用“加大推进力-快速通过”盾构施工模式。相反地,在距玄武湖隧道不低于6m处,为盾构机推进力量值切换点,应降低推进力-放慢掘进速度,并对玄武湖隧道底板进行监测,以保证超近接结构物的安全。

The mechanical behaviour of shield tunnel construction beneath adjacent existing highway tunnel is studied by using three-dimensional finite element numerical simulation method. The research demonstrates that it is dangerous to increase jack forces of the shield machine across adjacent upper existing highway tunnel which is considered as a kind of unloading structure. In addition, the jack forces of the shield machine is needed to be drop down to the limit value at 6m distance from the edge of upper existing highway tunnel and the measurement of the existing highway tunnel floor is enhanced in advancement process of shield machine to guarantee the safety of upper existing structure.