## 1 Introduction  
As coal mining operations continuously extend to deeper strata, rockburst disasters have become increasingly frequent, presenting a key risk to mine security [1, 2][PERSON] Thick and hard roofs, due to their strong integrity and resistance to collapse, tend to form large-span suspended structures during mining. Under stress concentration or structural failure, these roofs can suddenly release large amounts of stored energy, triggering rockburst events that severely endanger mining operations [3, 4, 5, 6][PERSON]  
The Hulusu Coal Mine in the Inner Mongolia Autonomous Region is taken as a representative case; the 2-1 coal seam is buried over 600 m deep and even overlain by a 20-30 m thick hard sandstone layer within the upper 100 m, which is intact and difficult to collapse. This leads to the frequent formation of suspended roofs and abnormal stress concentrations, creating typical conditions conducive to rockburst occurrence. Therefore, targeted research into prevention technologies for rockburst induced by tough and thick roofs is highly important in engineering.  
In recent years, extensive studies have been conducted domestically and internationally on rockburst control under thick hard roofs. For instance, [PERSON] et al. [7]explored roof weakening by blasting at the Jisan Coal Mine and proposed control strategies to release roof elastic energy through numerical simulations and field experiments. [PERSON] et al. [8; 9; 10] developed mechanical models to reveal the mechanisms of rockburst under thick hard roof conditions. [PERSON] et al. [11] investigated hydraulic fracturing as a method to reduce roof integrity and surrounding rock stress. [PERSON] et al. [12] proposed ground well acid fracturing techniques for pressure relief in overlying thick hard strata. [PERSON] et al. [13; 14; 15] combined physical similarity modeling with mechanical analysis to establish identification methods for rockburst-prone zones in complex thick-roof systems. [PERSON] et al. [16; 17; 18; 19] introduced combined surface and underground deep directional hydraulic fracturing methods, broadening the application range of rockburst prevention techniques. Despite these advances, significant scientific and technical challenges remain in the field of mine blasting for rockburst control. Traditional blasting-based techniques often rely heavily on empirical experience, lacking systematic theoretical frameworks that link geological conditions, mechanical responses, and fracturing outcomes.  
While current studies mostly focus on pressure relief in key layers or thick roofs within the main working faces, challenges remain in the implementation and parameter optimization of pressure relief above return airways. These challenges arise from limited working space and difficulties in controlling drilling angles. This study addresses the instability mechanism of rockburst under hard roof conditions in deep roadways and proposes a hydraulic fracturing-based pressure relief technique suitable for thick, hard overburden above return airways. Field validation was conducted in the 21,103 roadway of Hulusu Coal Mine. By designing pressure relief schemes with varying borehole inclinations and using FLAC3D numerical simulations, the influence of pressure relief upon the displacement and stress fields of surrounding rocks was construed to measure the optimum parameter combination under local geological conditions. Multisource monitoring--such as pressure variation in fracturing boreholes, water flow diffusion, and acoustic emission from roof fracturing--was used to assess the relief effect. The study achieved effective energy release and structural stabilization, providing a feasible technical path and theoretical basis for rockburst prevention in similar geological settings.