Calculation method and influencing factors of surface displacement during construction of curved shield tunnel
To analyze the variation law and influencing factors of surface displacement during the construction of curved shield tunnel.The mechanical model of curved shield tunnel excavation considering active articulated mechanism is established,and the calculation methods of surface displacement caused by additional stress and ground loss based on mirror method and orifice expansion theory are deduced respectively.Based on the actual project,the corresponding monitoring test and numerical simulation are carried out,the sensitivity index affecting the surface displacement offset of curved shield was researched.The results show that:The surface displacement of the curved section is offset to the inside of the tunnel in the direction of tunnel excavation,and the maximum displacement value and offset value of the curved section obtained by the calculation method are basically consistent with the measured values.It is found that the sensitivity of the imbalance coefficient is the highest,while the turning radius and excavation radius are sensitive in the curve over-digging gap factor.It is recommended that the thrust difference and over-excavation range of the inner and outer cylinders should be reasonably controlled in the construction of the curve section.
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