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Discussion on the Timing for the Secondary Lining Construction in Soft Ground Tunnels with High Geostress Based on Numerical Simulation and Measured Data Fitting
(China Railway 16th Bureau Group Corporation Limited, Beijing 100018)
Abstract The large deformation control for soft ground with high geostress in the railway tunnel is always a difficult problem in construction. Due to the uncertainty about deformation pattern and deformation time and the complexity of deformation mechanism, the timing for constructing the secondary lining in a high geostress environment has been a problem for construction personnel. For this reason, the large deformation pattern was studied combined with measured field data and numerical simulation and the timing of the secondary lining construction of the high geostress soft ground tunnel was discussed. The study results show that (1) the optimal timing for the construction of the secondary lining should be determined by using the dual control method of amount of deformation and rate of deformation, especially severe and extremely severe deformation sections. The secondary lining cannot be constructed until the amount of deformation reaches 95% of the estimated amount of deformation, the rate of crown settlement does not exceed 0.4 mm/d, and the rate of convergence of sidewall does not exceed 0.6 mm/d; (2) The relevance of exponential function fitting and time-history curve of deformation is high. In view of the complexity of tunnel surrounding rock, uncertainty of construction parameters and errors in measured data, it is not feasible to use a particular parameter for deformation curve fitting of all tunnels; and (3) in the analysis of construction timing for the secondary lining of tunnels prone to large deformation, the selection of creep parameters should be comprehensively considered according to stratum lithology and measurement results of adjacent strata.
Abstract：
The large deformation control for soft ground with high geostress in the railway tunnel is always a difficult problem in construction. Due to the uncertainty about deformation pattern and deformation time and the complexity of deformation mechanism, the timing for constructing the secondary lining in a high geostress environment has been a problem for construction personnel. For this reason, the large deformation pattern was studied combined with measured field data and numerical simulation and the timing of the secondary lining construction of the high geostress soft ground tunnel was discussed. The study results show that (1) the optimal timing for the construction of the secondary lining should be determined by using the dual control method of amount of deformation and rate of deformation, especially severe and extremely severe deformation sections. The secondary lining cannot be constructed until the amount of deformation reaches 95% of the estimated amount of deformation, the rate of crown settlement does not exceed 0.4 mm/d, and the rate of convergence of sidewall does not exceed 0.6 mm/d; (2) The relevance of exponential function fitting and time-history curve of deformation is high. In view of the complexity of tunnel surrounding rock, uncertainty of construction parameters and errors in measured data, it is not feasible to use a particular parameter for deformation curve fitting of all tunnels; and (3) in the analysis of construction timing for the secondary lining of tunnels prone to large deformation, the selection of creep parameters should be comprehensively considered according to stratum lithology and measurement results of adjacent strata.
MA Dong JIN Liujie WANG Wuxian HUANG Lixin
.Discussion on the Timing for the Secondary Lining Construction in Soft Ground Tunnels with High Geostress Based on Numerical Simulation and Measured Data Fitting[J] MODERN TUNNELLING TECHNOLOGY, 2022,V59(4): 137-146
2022, Vol. 59 