Subway tunnels are often designed as twin or multiline overlapping tunnels. The sheltering effect from the upper tunnel on the excavation of the lower tunnel is obvious. However, the mechanism of this sheltering effect has not been examined via detailed systematic research. Therefore, in this paper, centrifugal model tests on the excavation of vertical twin tunnels under typical sheltering conditions were carried out. Then, relevant numerical simulations were conducted, focusing on the change law of the ground and pipeline settlements and the principal stress and shear strain of soil under different sheltering conditions. Combining the results of the centrifugal model tests and relevant numerical simulations, for twin tunnels in an overlapping arrangement, the maximum ground settlement is caused by the excavation in the sequence of the upper tunnel first. However, for twin tunnels in a shouldering arrangement, the opposite sequence is caused by the sheltering effect. Sheltering effect is most prominent when the twin tunnels are in an overlapping arrangement. When the horizontal distance between the twin tunnels is 1DT, the ground settlement caused by excavation in the different sequences is the same. It is a critical state in which the sheltering effect is balanced with a disturbance effect. When the horizontal distance is from 1DT to 1.8DT, the sheltering effect gradually decreases, and the disturbance effect dominates as the distance increases. When the horizontal distance is more than 1.8DT, the sheltering effect basically disappears, and only the disturbance effect exists. Finally, the sheltering coefficient C is proposed, which is related to the horizontal distance between the twin tunnels. By introducing the stochastic medium theory, an equation is proposed, which can quantitatively predict the ground settlement by excavation under sheltering effects at different horizontal distances.

地铁隧道通常设计为双线或多线重叠隧道。上部隧道对下部隧道开挖的防护作用是明显的。但是，尚未通过详细的系统研究来研究这种掩盖作用的机理。因此，本文在典型的掩蔽条件下对竖向双隧洞的开挖进行了离心模型试验。然后，进行了相关的数值模拟，重点研究了地面和管道沉降的变化规律以及在不同掩蔽条件下土壤的主应力和剪应变。结合离心模型试验的结果和相关的数值模拟，对重叠布置的双隧道进行了研究，最大的地面沉降是由上层隧道先开挖引起的。但是，对于肩部布置的双隧道，相反的顺序是由遮挡作用引起的。当双隧道重叠布置时，庇护效果最为显着。当双隧道之间的水平距离为1DT时，不同顺序的开挖引起的地面沉降是相同的。这是临界状态，其中遮蔽效应与干扰效应是平衡的。当水平距离从1DT到1.8DT时，掩蔽效果逐渐降低，并且随着距离的增加干扰效应起主导作用。当水平距离大于1.8DT时，掩蔽效应基本消失，仅存在扰动效应。最后，提出了掩护系数C，该系数与双隧道之间的水平距离有关。通过引入随机介质理论，提出了一个方程，该方程可以在不同水平距离的掩护作用下，通过开挖定量地预测地面沉降。