Effects of shield construction on dynamic characteristics and deformation of interlayer soil: A case study in Changchun, China

Shield tunneling can cause deformation of the interlayer soil. Traditional static methods do not consider the shield dynamic load and the construction influence on the dynamic performance of interlayer soil, resulting in inaccurate results. Therefore, this paper proposes a dynamic analysis method to assess soil deformation. Firstly, the composition and stress state of interlayer soil were monitored on site. Secondly, the dynamic triaxial tests were conducted based on the monitoring results to analyze the soil dynamic characteristics. Then, a dynamic constitutive model of the interlayer soil was constructed, which considers the change of the dynamic performance. Finally, the dynamic effect of shield on soil is simulated based on viscoelastic mechanics, and the dynamic analysis of interlayer soil deformation is realized by three-dimensional finite element method. The results indicate that the interlayer soil near the excavation face is more significantly affected during the crossing stage. Shield construction increases the dynamic strength and dynamic modulus of the interlayer soil, while reducing the damping ratio. The Hardin-Drnevich model and the logarithmic-linear model can well describe the evolution laws of dynamic modulus and dynamic strength. The dynamic analysis method is closer to real construction and has higher prediction accuracy.