Transverse deformational behaviors of segmental lining during shield tunneling: A case study

In order to better understand the deformational behaviors of lining segments during shield tunneling, a case study of the real-time monitoring on the deformation of a constructing shield tunnel in Shanghai by using the wireless sensor network (WSN) is presented. Eight tilt WSN nodes are installed on two rings with monitoring frequency of 10 min right after the erection of the rings. The nodes monitor the tilt change of segments in the tunnel cross section until the completion of the tunnel. The deformational behavior reflected by the rotation of segments reveals two kinds of deformation mode of tunnel ring during construction: the rotation and the ovalization. The rotation direction of tunnel ring is opposite to that of shield cutter. The direction of major axis of ovalization is horizontal most of the time and become vertical when the grouting of shield tail acts on the segments. When the lining segments are buried in the shield machine, the rotation of the ring plays an important role. The value of rotation is closely related to the cutter torque, and the relative rotation between the two monitored rings is 7.9 mm, which is large and needs considering as a load on tunnel structure during construction. While the lining segments are pulled out of the shield tail, the ovalization model are gradually dominant in these two modes. The horizontal diameters of rings show an increase-decrease-increase trend.