Application of WSS in Mined Tunnel Crossing under the Existing Shield Tunnel

Beijing subway line 6 crossing under the existing line 4 is the first domestic method of using the mined tunnels crossing under the existing interval shield tunnel, during the crossing process, the key of engineering control is the displacement of existing line and construction line. Dynamic numerical simulation for the crossing process has been made by FLAC3D, and the displacement and its change law of the existing line and construction line with the different WSS reinforcement measures are obtained.The conclusion show that the WSS reinforcement measures of upper semi-section achieves the balance of safety and economy,but the uplift of WSS to the existing line should be noted in the actual construction.