Nonlinear anisotropic finite element analysis of liquefiable tunnel–sand–pile interaction under seismic excitation

Abstract

Nonlinear time‐history analysis can be used to determine the liquefiable behaviors of the tunnel–sand–pile interaction (TSPI) model with the consideration of sand anisotropy. This study presents the nonlinear response of the TSPI model with the existence of liquefaction under seismic excitation. The analysis reveals that tunnel and pile behave as isotropic elements, while sand shows isotropic, orthotropic, and anisotropic characteristics. Three constitutive models including UBC3D‐PLM (two yield surfaces associated with the hardening rule), NGI‐ADP (yielding with associated plastic potential function), and a user‐specified constitutive model are adopted to evaluate the isotropic, orthotropic, and anisotropic behaviors of sand. On this basis, two finite element‐based codes (ETABS 18.1.1 and Plaxis 3D) are used to evaluate sand behaviors and responses. Responses of the tunnel, sand, pile, and excess pore pressure ratio are recorded in the interaction zone by varying the pile diameter, tunnel diameter, and tunnel–pile clearance. Compared with the orthotropic and isotropic conditions, lower variations of results are found in the anisotropic condition, except for the case of generation of excess pore pressure. In addition, the present reanalysis results are in agreement with previous analytical and case study results, which further indicates the effectiveness of the finite element‐based numerical codes.

Investigation on the Gas Emission Law of Water-Containing Coal across the Rank Range

“…The higher adsorption capacity and the swelling potential can lead to a significant alteration in the coal porosity. 61 − 63 This also leads to the decrease in migration channels and affects gas emissions within coal, which will be further studied in our future work.…”

“…In addition, coals have numerous adsorption sites for water molecules and consequently they have significant swelling potential upon water adsorption. The higher adsorption capacity and the swelling potential can lead to a significant alteration in the coal porosity. − This also leads to the decrease in migration channels and affects gas emissions within coal, which will be further studied in our future work.…”

Analytical formulations of tunnel–soil–pile interaction under seismic excitations

“…In addition, several authors evaluated the dynamic tunnel–soil interaction under seismic loading numerically and analytically 22–27 . In most recent studies, TSPI responses were evaluated numerically in liquefiable conditions considering the sand isotropic 2 and anisotropic 3 conditions. However, the tunnel–soil interaction depended on the horizontal and vertical springs for P, SH, and SV waves, and the stiffnesses of these springs were related to Kelvin's and Flamant's problems 17 …”