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Numerical Analysis of the Influence of a Cavity behind the Shield Lining on the Tunnel Structure
(1 Shanxi Provincial Major Laboratory for Highway Bridge & Tunnel, Chang′an University, Xi′an 710064; 2 Zhengzhou Xinggang Investment & Development Group Co. Ltd., Zhengzhou 450016; 3 Geophysical Test Center, China Railway First Group Co. Ltd., Xi′an 710055)
Abstract A numerical analysis of the influence of a cavity behind the lining of a shield tunnel was performed in respect to the position and size of the cavity based on the water inflow of a running tunnel on the Xi′an metro using ANSYS software. The results show that: 1) the contour line of the stress concentration factors (SCF) is presented in a butterfly shape—with the largest stress concentration at the top and bottom of the tunnel and the smallest ones at the two side—if there is no cavity behind the lining; 2) if the cavities behind the lining are located at the two sides, it has a significant impact on the stress concentration of the surrounding rock, internal force and safety factor of the segment and the impact decreases with the movement of the cavity toward the top and bottom of the tunnel; 3) with an increase of distance from the cavity, the impact on the stress concentration of the surrounding rock, internal force
and safety factor decreases; 4) axial force is less affected by the cavity size while the segment bending, stress concentration of the surrounding rock and safety factor are much more affected by the cavity size; and 5) with an increase of the cavity area, the impact of the cavity on the stress concentration of the surrounding soil mass, internal force and safety factor of the segment increases.
Abstract：
A numerical analysis of the influence of a cavity behind the lining of a shield tunnel was performed in respect to the position and size of the cavity based on the water inflow of a running tunnel on the Xi′an metro using ANSYS software. The results show that: 1) the contour line of the stress concentration factors (SCF) is presented in a butterfly shape—with the largest stress concentration at the top and bottom of the tunnel and the smallest ones at the two side—if there is no cavity behind the lining; 2) if the cavities behind the lining are located at the two sides, it has a significant impact on the stress concentration of the surrounding rock, internal force and safety factor of the segment and the impact decreases with the movement of the cavity toward the top and bottom of the tunnel; 3) with an increase of distance from the cavity, the impact on the stress concentration of the surrounding rock, internal force
and safety factor decreases; 4) axial force is less affected by the cavity size while the segment bending, stress concentration of the surrounding rock and safety factor are much more affected by the cavity size; and 5) with an increase of the cavity area, the impact of the cavity on the stress concentration of the surrounding soil mass, internal force and safety factor of the segment increases.
.Numerical Analysis of the Influence of a Cavity behind the Shield Lining on the Tunnel Structure[J] MODERN TUNNELLING TECHNOLOGY, 2017,V54(3): 126-134
2017, Vol. 54 