Study on transverse effective rigidity ratio of shield tunnels

After a detailed discussion on the transverse effective rigidity ratio of shield tunnel,it was shown that the effective rigidity ratio was always an emperical value.Based on the model test of two-ring tunnel structures and the analysis of the test results,some conclusions could be drawn.The relation of deformation of tunnel structure with the load was clearly linear elastic,so the effective rigidity of shield tunnel was constant in elastic stage,which was agreeable to the rule of the modified conventional design method;the effective rigidity ratios of tunnel with nonstaggered and staggered installation were 0.67 and 0.75 respectively for Shanghai Metro;the effect of soil resistance on the effective rigidity of shield tunnel was very small in soft ground.Compared with empirical formulas and structural tests,the model test could be done conveniently,with abundant believable results and economical cost,and would be a good method to study the effective rigidity of shield tunnels.