Work

Tunnel support in red bed soft rocks considering hydro-sensitivity and time-dependent behaviors: A review

Year: 2026

Type: article

Abstract: Red bed tunnel engineering presents significant challenges due to the combined effects of hydro-sensitivity and time-dependent nonlinear mechanical behavior of the surrounding rock masses. Despite critical stability concerns, globally recognized standardized design methodologies for support systems in such geological conditions are still under development. This comprehensive review systematically examines recent advancements in support technologies for red bed tunnels. The following conclusions can be drawn. First, based on the hydro-sensitive and time-dependent nature of red bed rocks, four dominant failure modes are identified: hydro-mechanical weakening failure, low-strength material failure, bedding plane-controlled structural failure, and time-dependent deformation failure. The applicability and performance of three representative stabilization strategies – prestressed anchorage, rock mass grouting, and yielding support systems – are then critically evaluated across different tunnel service stages. Second, prestressed anchorage and grouting are shown to effectively mitigate construction-phase instabilities caused by low rock strength and pronounced bedding structures, particularly using specialized anchorage systems and hydro-sensitive grouting materials that significantly enhance the mechanical properties of red bed rock masses. Third, for long-term tunnel operation, the incorporation of compressible layers between the surrounding rock and secondary lining is highlighted as an effective solution to accommodate time-dependent deformation and prevent lining damage, with recommended ranges of mechanical parameters summarized from existing studies. Finally, key research frontiers are discussed, including the time-dependent anisotropic behavior of stratified red bed rock masses, scale effects in prestressed anchorage systems, and viscoelastic–plastic interactions in yielding support designs. The potential application of resilience-based design concepts is also emphasized, offering new perspectives for improving the long-term safety and adaptability of tunnels constructed in red bed soft rock formations.

Source: Journal of Rock Mechanics and Geotechnical Engineering

DOI: 10.1016/j.jrmge.2025.09.035

Authors: Weizhong Chen, Xiaoyun Shu, Hongming Tian, Chenming Yang, Xianjun Tan, Zhende Zhu