The span between two such diaphragm walls can easily be bridged with precast reinforced concrete beams or a cast in-site reinforced concrete slab to complete the main shell of the tunnel.

• 使用预制钢筋混凝土梁或者现浇钢筋混凝土板会很容易将两侧地下连续墙的跨度空间连接起来,从而完成隧道的主壳。