To meet the ever growing needs of economical and social activities in emerging countries, a great number of tunnels have been built to narrow the physical distance and improve the transport efficiency, especially in China and developing countries. However, engineers have been faced with various complicated geological and operational environments, such as high temperature, high geo-stress, heavy vehicle loads from cargo trains, and dynamic loads from high-speed trains, as well as corrosive liquids. These complicated geological and operational environments often significantly slow down construction progress and induce decay and failure of tunnel structure, threatening the safety of the tunnel and the lives of site engineers. Therefore, creative construction technology, innovative design methods, and scientific maintenance techniques that are applicable for building and maintaining tunnels in unfavorable environments should be systematically investigated and studied.

The purpose of this Special Issue is to create a channel for knowledge sharing of technical treatments toward tunnels in harsh geological and operational environments during the design, construction, and operation stages. Research in this field can be interdisciplinary, involving hazardous geology, chemistry, non-destructive testing, remote sensing, computer vision, machine learning, and numerical calculation. For instance, an automatic displacement monitoring system based on computer vision technology could be an ideal solution to identify the abnormal deformation of a tunnel in a rapid and efficient manner during the operation period. Also, we especially welcome hybrid artificial intelligence research in this field.

Potential topics include but are not limited to the following:

• Novel site investigation and data collection techniques
• Advanced constitutive models for surrounding rocks and tunnel concrete linings
• Research on design and construction methods of tunnel structures in the harsh geological conditions such as high ground temperature or high geostress
• The mechanical properties evolution law and corresponding treatments for bottom structures of tunnels under heavy train loads
• The deterioration characteristics and the properties control methods of tunnel structures against corrosive geological environments
• An intelligent system for whole life-time monitoring of service performance of tunnel using digital image and artificial intelligence technology
• The aerodynamic response of tunnel structures under high-speed train load
• Mechanical responses of both tunnel structure and surrounding rock media subject to dynamic loading or earthquakes
• Stability and risk analysis of tunnels under both construction and operation
• Water tunnels or oil/water/gas pipelines subjected to blasting
• Risk assessment/construction management for the consideration of impacts induced by the COVID-19 pandemic
• Construction/technology/numerical analysis of deep tunnels (more 1000 meters)
• Tunnel facility operation maintenance and management