随着地铁网络不断完善，新建盾构隧道近距离穿越既有隧道的现象越来越多。盾构隧道近距离穿越既有隧道的影响问题，比常规盾构施工的研究更为复杂。采用离心模型试验对盾构下穿越对既有隧道以及周围地层的影响进行了研究。选用排液法在离心场中模拟盾构施工，实现了在不停机状态下模拟隧道开挖卸载、地层损失和注浆过程，并分析了盾构下穿越施工引起的地层及既有隧道的纵向位移变化规律。研究成果可为盾构近距离施工控制措施提供参考。

The impact of newly-built shield tunnel which crosses the nearby tunnel is much more complicated than ordinary shield tunneling in intact soil strata. Centrifuge modeling was performed to study the effects of shielding tunneling on the nearby strata and the existing tunnels. In the centrifuge model test, fluid-discharge method in the centrifuge field was employed to simulate the shield construction. The processes of excavation unloading, ground loss and grouting were simulated without stopping the excavation. Besides, the settlement and longitudinal deformation of the nearby strata and the existing tunnels induced by shielding tunneling below were analyzed. The research results will be referential for the control over shield construction near existing tunnels