Effect of Adjacent Excavation on Existing Tunnels in Spatially Variable Soil

The inherent spatial variability of soil properties is the main sauces of uncertainties in the site investigation, and it is commonly characterized using random field theory. Adjacent excavation has a significant influence on the tunnel, which has been investigated in recently years. However, the existing studies usually assume that soil is deterministic, ignoring the spatial variability of soil parameters. Therefore, the objective of this study is to characterize the effect of excavation on adjacent tunnel in spatially variable soil. The Hardening Soil model with small strain stiffness (HS-Small) is used in this study to present the increased stiffness of soils at small strains, a popular choice in excavation engineering. The modulus parameters in the HSS model are modeled as random field. The established numerical model is firstly verified using an actual engineering. There are six indexes to evaluate the influence of excavation on tunnel, including the deformation and angle of tunnel. Meanwhile, an amplification factor simplified method is proposed to present the effect of soil spatial variability. The influence of different relative positions of the existing tunnel and adjacent excavation in spatially variable soil are comprehensively studied. The isocontour distribution diagram of the overall horizontal and vertical movement of the tunnel is given to provide certain references for subsequent similar working conditions.