Abstract:

In this study, a case study is conducted on shield tunnel with small curvature radius on Qingnian road connecting line of Nantong metro line 1, and the tunnelinginduced disturbance on stratum and tunnel structure is monitored and analyzed. A threedimensional numerical model of shield tunneling is established to simulate the tunneling process. The results show the following: (1) The surface settlement outside the curve is less than that inside the curve. (2) The overexcavation of the cutterhead at the inner side produces an additional unloading effect. As the consequence, the vertical displacement of the soil above and below the tunnel increase dramatically. (3) The horizontal displacement of the soil at the upper sides of the tunnel is basically symmetrical, and moves towards the tunnel center. (4) The horizontal displacement of the soil at the tunnel center is asymmetric, and moves towards outside of the tunnel at both sides of the tunnel.

Key words: small curvature radius, shield tunnel, sandy stratum; stratum disturbance, insitu monitoring, numerical simulation