地铁盾构隧道下穿南水北调干渠的沉降控制研究

Settlement Control of Subway Shield Tunnel under the Main Channel of South-to-North Water Diversion under Complex Conditions

通过对地铁盾构隧道下穿南水北调干渠时沉降现场监测数据和数值模拟结果的分析,对干渠结构、干渠上部倒虹吸结构和地表的沉降控制进行了研究。结果表明:(1)盾构隧道下穿南水北调干渠时,干渠结构最大沉降发生在干渠底部。在盾构隧道与干渠渠底净距为2.5D(D为盾构隧道外径)并采用克泥效工法时,干渠结构的最大沉降量为11.26 mm,未采用克泥效工法时,干渠结构的最大沉降量为14.52 mm,说明采用克泥效工法能够有效减少干渠结构的沉降量,减少幅度为22%,同时也能够有效降低地表和倒虹吸结构的沉降量;(2)随着盾构隧道与干渠的距离越来越接近,干渠底部、地表和倒虹吸结构的沉降量逐渐增大,且随着盾构隧道与干渠渠底净距的减少,其沉降量的增大幅度逐渐提高;(3)采用克泥效工法时,盾构隧道与干渠的净距不少于2.0D时,能够保证干渠底部的沉降量不大于15 mm。该研究结果可为类似工程提供参考。

Based on the field monitoring data and numerical analysis of shield tunnel under the main channel of South-to-North Water Diversion project under complex conditions, this paper studies the settlement control of main channel and upper inverted siphon. The results are as follows:(1)When shield tunnel passes under the main channel, the maximum settlement of occurs at the bottom of the main channel. When the net distance between the shield tunnel and the main channel bottom is 2.5D(D is the out diameter of shield tunnel),the maximum settlement of the main channel is 11.26 mm with the mud control method, and 14.52 mm without it, which indicates that with the mud control method, the main channel settlement can be effectively reduced by 22%,and the settlement of the surface and inverted siphon structure can be effectively reduced, too;(2)As the distance between the shield tunnel and the main channel gets closer and closer, the settlement at the bottom of the main channel, surface settlement and the settlement of the inverted siphon structure gradually increase, and as the net distance decreases, the increase in settlement gradually turns large;(3)Under the condition of adopting the mud control method, the settlement of main channel can be ensured to be no more than 15 mm when the net distance between the shield tunnel and the bottom of the main channel is no less than 2.0D.The result may provide reference for similar projects.