Abstract：
The Beihaibei-Nanluoguxiang running tunnel on Beijing Subway Line 6, which goes from running paral? lel on top and bottom to running parallel on the left and right and is excavated from the right tube (down line) to the left tube (up line), is the first bored overlapping tunnel in the Beijing area. Based on an analysis of surface settlement data measured by 18 monitoring sections, the law of ground surface deformation induced by the bored overlapping tunnelling was obtained. The research results show that: 1) with an increased angle and distance of the tunnel tubes, the overlapping effect of the strata settlement increases obviously and the influence of the later-built right tube on surface settlement increases gradually; 2) excavation of the left tube changes the form of the surface settlement trough, makes the maximum surface settlement deviate from the right tube and widens the settlement trough; 3) the existing structure obstructs deformation transmission and reduces surface deformation, which is more obvious for the double-tube tunnel compared with the single-tube tunnel; and 4) deep-hole grouting can effectively control surface settlement and reduce the influence of construction on the surrounding environment.
2017, Vol. 54 