With the progress of society and energy transformation, there is an increasing need to carry out major infrastructure projects, such as large-scale water conservation projects, underground nuclear waste storage projects, deep-earth resource extraction and geo-thermal exploitation projects. The plane of weakness, such as joints, fissures and faults are inherent to the rock mass. These inherent structures would be further expanded under the influence of geological movements and human activities. The interpenetration, cutting, connection, etc., between these structural surfaces eventually form a complex and potentially dangerous micro-fracture grid system.

The investigations into the causes of numerous engineering accidents throughout human history have confirmed that such weak structural planes are responsible for the accidents and that this microfracture system is not determined by any mono-physical field, but is influenced by a combination of hydraulic field, mechanical field, thermal field, and other physical fields. Given the enormous detrimental and complex nature of microfracture systems in rock masses, it is imperative that further detailed studies on the seepage characteristics of the weak structural planes and microfractures under the coupling of multiple physical fields are carried out.

This Special Issue is dedicated to bringing together high-quality original research and review articles highlighting recent advances and new insights of fractured rock mass seepage characteristics under multi-field coupling. Submissions showcasing theoretical analysis, laboratory testing, numerical modeling, and in-situ investigations are welcome.

Potential topics include but are not limited to the following:

• Rock fracturing and permeability enhancement mechanisms
• Water-rock interaction under multi-physical field coupling
• Indoor experiments of seepage behaviors of fractured rock mass under multi-field coupling
• Novel numerical methods of fluid flow in fractured rock mass
• Advanced theory of the multi-field coupling theory of water, force, and heat in rock mass
• Mechanical properties of rock mass during seepage
• Models and algorithms for assessing fracture propagation
• Reinforcement methods for fractured rock mass
• Geochemical reactions in fractured rock mass
• Novel methods and technology for monitoring deep fluid flow behaviors