Urban underground structures,especially tunnels,subways,and pipeline systems,are all crucial parts of the infrastructure of modern society.By the end of 2021,China had opened rail transit operations in 51 cities with a total mileage of 8708 km.Considering their importance for life safety and the economy,appropriate seismic design is of prior necessity.Historically,underground infrastructure has experienced a lower rate of damage than surface structures.However,recent earthquakes,such as the Osaka-Kobe earthquake (1995),the Wenchuan earthquake (2008),have challenged the previous perception.In this special issue,ERA compiled and published related research articles investigating timely advances on the seismic performance of underground structures.The special issue includes 10 papers,covering the experimental investigation of the seismic response and damage of underground structures under different adverse soil conditions,isolation methods for underground structures,etc.
In terms of seismic resistance of underground structures,Wu et al.(2022) carried out numerical simulation and the pushover analysis method on 12 conditions with different soil-structure flexibility ratios.The results show that the sensitivity of calculation accuracy of the pushover analysis method is affected by the soil-structure flexibility ratio,of which the fluctuation range is generally between-15%–15%.Zhuang et al.(2022) demonstrated 2D time-domain nonlinear finite element models for the static-dynamic coupling interaction between soil and underground structure to obtain the seismic performance of the underground subway station with advanced Elastic Sliding Bearings (ESBs)system.Tang et al.(2022) investigated irregular section underground structures by numerical simulation and the shaking table test.Ma et al.(2022)present a numerical study on the seismic response of underground structures influenced by the spatial variability of the field.Wang et al.(2022)proposed new installing isolation devices and carried out a series of numerical simulation calculations,revealing the influences of isolation devices on the seismic isolation of underground structures.
In applications of soil-structure dynamic interaction and structural dynamics,the equivalent linear method is used to analyze the nonlinear problem by adding an artificial viscoelastic boundary to the boundary of the thicknessless contact element (Li and Yin,2022).Hou et al.(2022)considered the influence of the foundation form of raw soil structure on seismic vulnerability.Then,the seismic vulnerability of the raw soil structure was analyzed by using the vulnerability function,and the influence of the spiral anchor composite foundation form on the seismic vulnerability of the raw soil structure was studied.The static response and dynamic response of the plunge pool were analyzed respectively for the vibration response of the plunge pool and related areas under the condition of flood discharge (Yuan et al.,2022).Based on the full-scale test results of precast columns connected with grouted sleeves and the correctness of the numerical models,Liu et al.(2022) conducted the influence analysis of the individual and coupling action of the grouted sleeves and assembled seam on the deformation and bearing capacity of the precast column.Bao et al.(2022)carried out a comparative analysis of the seismic response of the shallow buried underground structures under incident P,SV and Rayleigh Waves.
Overall,this special issue presents some high-quality research papers and reports related to both modelling and validation,which can strengthen our understanding of the earthquake-induced impacts on underground structures and help improve the safety of users.In addition,these papers will greatly increase the academic influence of ERA.Finally,we would like to thank all the authors and reviewers;this special issue cannot be published on time without their contributions.
