Numerical Study on Dynamic Analysis of River-crossing Large Sectional Shield Tunnel

摘要

This paper reports the dynamic analysis of river -crossing shield tunnel for evaluating the performance to resist earthquake. r The target project is a large sectional shield tunnel with double -deck structure in Nanjing area. The tunnel underground r cross complex geological area where acute changing irregular sedimentary layer of soil and rock , with high pressure ground r water and so on. This dynamic analysis is performed on smart soil -structure model consists of segments and bolts. r Three-dimensional dynamic finite element method (3DFDM)is applied on smart soil-structure model through inputing scientific r level waves considering Nanjing regional condition and modified records during 2008 Wenchuan earthquake Ms 8. 0. The results r indicate that, (1) the seismic response shown complex formation patterns in soft soil , composite soil and the bedrock. , r main difference caused complex geological conditions is observed. (2) the maximum stress appears in junction of vertical r shaft and shield tunnel ,the maximum deformation occurs located in the part near the junc -tion also. (3) in the r tunnel,largest stress-value is shown in spandrel and vault ,and the maximum deformation is appeared near the vault or the r bottom of the arch. (4) the acceleration and displacement in the bolts are effected with the rigid of structure and the r mechanical parameters of soil. The stress distribution in bolts is volatility. (5) the influence on dynamic analysis by r inputting the Wen -chuan wave is larger than the case of Nanjing wave. Our results indicate that the structure will not r failure caused by the design acceleration ground motion with 2 percent probabiliy of exceedance in 50 years.