Damage Characteristics and Parameter Sensitivity of Fracture Caverns Under Pneumatic Disturbances

Abstract

In the construction process of abandoned mine compressed air energy storage projects, the presence and distribution of fractures within the rock mass significantly influence both the design and safe operation of the energy storage system. To investigate how initial fractures affect rock mass damage under pressure disturbances, a coupled model was developed to analyze fracture damage through fluid-solid interaction based on the evolution equation for rock mass damage. The COMSOL numerical simulation software facilitated an orthogonal experiment examining geological conditions and fracture distribution morphology to explore the primary and secondary relationships among various factors affecting the extent of rock mass damage. The research findings indicate that: (1) The sensitivity of geological conditions in relation to cavity rock mass damage is ranked as follows: injection pressure > rock mass strength > depth; (2) The length, width, and dip angle of fractures collectively influence the degree of rock damage. Notably, variations in length and width directly alter the damaged area, while changes in dip angle primarily affect vertical extension of this area; (3) Among three morphological configurations observed in longitudinal sections of throughway fractures, their sensitivities to ranges of rock mass damage differ according to this order: fracture length > fracture dip angle > fracture width; (4) From both microscopic and macroscopic perspectives, injection pressure, rock mass strength, fracture length, and dip angle exert a highly significant impact on the range of rock mass damage. In contrast, depth and fracture width demonstrate relatively weaker effects. These research results provide valuable insights for selecting appropriate strategies during construction phases for abandoned mine compressed air energy storage projects.