Analysis of the Parameter Values for Settlement Trough Width Induced by Shield Tunnel Excavation in Deep Soil
To investigate the variation patterns of the deep soil settlement trough shape caused by shield tunnel exca-vation,existing empirical formulas for deep settlement were summarized.Based on the collected field measurements and model test cases—21 groups for clay,20 groups for sandy soil,and 8 groups for gravel—the settlement trough width parameter K(z)was analyzed through back-calculation.The findings indicate that in any type of stratum,both hyperbolic and power function empirical formulas can effectively describe the trend of the settlement trough width parameter K(z)with the depth ratio.The recommended empirical parameter values for clay and sandy soil are c=0.323、0.197,and n=0.479、0.456,respectively.In gravel layers,the settlement trough width parameter shows a sim-ple linear relationship with the depth ratio.