土压平衡盾构水下始发段掘进参数对地表沉降的影响分析

以广佛环线沙堤隧道为工程依托,利用有限差分软件FLAC~(3D)研究了土压平衡盾构水下始发段掘进参数对地表沉降的影响,并结合现场实测数据分析盾构掘进过程中地表沉降和邻近建筑物变形的变化规律。结果表明:地表沉降与土压平衡盾构掘进参数密切相关,增大土舱压力与注浆压力可以减小地表的沉降,但掘进参数的调整存在合理范围,超合理值后过沉降的控制效果变化不明显;现场实测数据表明:土压平衡盾构施工引起的地表沉降及建筑物变形行为由前期扰动、通过扰动、停机影响、后期扰动4部分组成,其中停机对地表沉降影响很大,因此施工中需尽量避免停机并提前做好防范措施;实际采用的掘进参数仍有一定的调整空间,施工中应根据地层情况及时调整相关的掘进参数以减小施工影响。

Analysis on Impact of Underwater Tunneling Parameters of Soil Pressure Balance Shield on Surface Settlement

Based on the Shadi shield tunnel on Guangzhou-Foshan ring railway, the influence of excavation parameters of the underwater starting section of the soil-pressure balance shield on the surface settlement is studied by using the finite difference software FLAC3 D, and the variation law of surface settlement and the deformation of adjacent buildings in the process of shield tunneling are analyzed with field measurement data. The results are as follows: surface subsidence is closely related to the tunneling parameters of the soil pressure balance shield, the surface settlement can be reduced by increasing the pressure of the soil chamber and grouting pressure; however, the tunneling parameters have a reasonable range of adjustment, and the effect of over-settlement control does not change significantly once the reasonable value is exceeded. Field measurement data show that the ground settlement and building deformation caused by the construction of soil pressure balance shield are composed of four stages of early disturbance, through disturbance, shutdown effect, and late disturbance. As shutdown has a great impact on surface subsidence, it is necessary to avoid it as much as possible in the construction. The tunneling parameters still remain to be adjusted, and relevant tunneling parameters should be adjusted timely according to the formation conditions in construction to reduce the impact caused by construction..