A dynamic seepage analysis method for engineering-disturbed rock mass considering microseismic-derived fractures: a case study

Abstract

The evolution of fractures in rock masses induced by engineering disturbance is fundamental to the development of seepage pathways and changes in the seepage field, playing a critical role in the assessment of seepage-related disasters. This study proposes a dynamic seepage analysis method for engineering-disturbed rock mass considering microseismic(MS)-derived fractures. A three-dimensional random pre-existing fracture network model is established, with its connectivity determined through numerical water injection tests, and the preferential seepage channels are characterized using a graph structure. The coupling fracture models are constructed by integrating MS-derived fractures with the pre-existing fracture network, and the evolution of seepage field is tracked. The results show that among the size, number, dip direction and dip angle of MS-derived fractures, the connectivity is most influenced by the size. Increasing the MS-derived fracture radius from 0.5 m to 1 m enhances the model's water-holding rate by 47.87 % and connectivity rate by 11.46 %. The proposed method is applied to Jinzhou underground water-sealed storage cavern with seepage disasters. It is found that MS-derived fractures affect the seepage of the pre-existing fracture network in two ways: by directly connecting pre-existing fractures that were originally impermeable and non-interconnected to enhance the connectivity, and by indirectly changing the water pressure distribution in the surrounding rock mass. In addition, the locations of the preferential seepage channels during construction are identified, with seepage points exhibiting velocities of 1.93 × 10⁻⁵ m/s and 1.14 × 10⁻⁵ m/s. The results provide a new idea for identifying seepage channels and optimizing grouting schemes in engineering-disturbed rock mass.