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• Concentrated vertical stress steers high-stress strike-slip roadway instability. • The high-stress strike-slip unloading tri-zone is defined with the in-situ stress. • Establish a corresponding optimized borehole diameter-spacing design method. • Field tests were successfully carried out according to the research results. To effectively address instability and control failure caused by high roadway stress, this study focuses on the engineering context of the Jinfeng Gold Deposit in southwestern Guizhou. It simulates and analyzes the response of surrounding rock in high-stress roadways affected by strike-slip stress distribution (σ H ＞ σ v ＞ σ h) under varying drilling and pressure relief parameters, and conducts on-site experiments and monitoring. The study reveals that under strike-slip stress conditions when stress relief in the roadway's surrounding rock equals the initial vertical stress, the stress distribution maintains a 'bimodal' pattern. Establish an evaluation method for the stress range in the three-zone during pressure relief and the optimization of drill hole diameter-spacing design. The optimized drilling relief plan effectively shifts stress concentration, and the peak stress near the roadway decreases to the original rock stress level, with a 3.5 MPa reduction at the far end and a horizontal shift of 4.79 m with the unloading level (ε L) reaches 0.8375. Practical implementation confirms the effectiveness of the pressure relief design in unloading and transferring stress from the high-stress roadway's stress concentration area, achieving a 43.14 % deformation optimization on both sides of the roadway. These findings provide valuable references for controlling stress relief in high-stress roadways surrounding rock. [ABSTRACT FROM AUTHOR]

• Deformation and failure mechanism analysis of deep high-stress fractured roadway. • Establishment of the surrounding rock-support coupling model. • Mechanical response characteristics of CFST support under dynamic disturbance. • Supporting effect evaluation of CFST support by microseismic monitoring. • Field test of CFST support control technology. To address the problem of deep high-stress fractured roadway support, a water sump in a 30 m middle section of the Jinfeng Gold Deposit was taken as an engineering background. The deformation failure characteristics of the roadway under the original support scheme were analysed, and the deformation failure mechanism was assessed by combining the geological conditions, geological mechanism, and original support scheme. Numerical experiments were performed to analyse the bearing performance of concrete-filled steel tubular (CFST) supports and U-shaped steel supports under dynamic and static loads. The experiments showed that with the same lateral pressure coefficient, the stress of CFST support is approximately half of that of U-shaped steel support, and the deformation is decreased by 30–40 %. Meanwhile, under the same charge weight, the stress and deformation of the CFST support are always lower than those of the U-shaped steel support. In engineering practice, the support scheme based on circular-section CFST supports showed no obvious deformation after sixty days of use, and the surrounding rock produced few microseismic events and no significant expansion or concentration of microfractures. The stability of the roadway surrounding rock was efficiently maintained, which offers guiding implications for similar projects. [ABSTRACT FROM AUTHOR]

The Lower Cambrian Niutitang Formation is one of the most important shale reservoirs in the Northern Guizhou. To study the characteristics of pore structures and the relationships between shale's physical properties and pore structures in the complex tectonic area, from the perspective of hydrocarbon generation and evolution, the mineral composition, pore structure characteristics of shale samples in northern Guizhou were analyzed using X-ray diffraction (XRD), optical microscopic composition analysis, focused ion beam-scanning electron microscopy (FIB-SEM), vitrinite reflectivity and nitrogen adsorption experiments. Results indicate that the pore structures can be categorized into conical, ink bottle, spherical, elliptical, beaded, irregular, and plate-like intersecting microfractures. Shale samples are organic-rich with an average total organic carbon content of 4.39%. Organic matter is consumed within the shale matrix during the hydrocarbon generation and evolution, which increases the organic pore size and the proportion of organic pores. The high TOC content is conducive to developing organic pores. In addition, the average content of brittle minerals is greater than 70%. High content of brittle minerals during diagenesis is conducive to developing the residual pores at the edges of mineral particles and dissolved pores within mineral particles. Thus, the high content of brittle minerals and TOC content is favorable for the development of meso-macropores. The content of clay minerals within the shale samples ranges from 6.3% to 42.2%, with an average of 20.02%. Micropores and mesopores mainly occur in the clay minerals. Pores in clay minerals are easily compacted under tectonic stress. Meanwhile, high thermal evolution degree and the vitrinite reflectance R o greater than 3.5 is not conducive to developing pores. Hence, high TOC content, high brittle minerals content, and thermal evolution degree ranging from 0.6% to 3% make the Lower Cambrian Niutitang Formation shale reservoirs favorable for shale gas exploration. • The pore structures in the complex tectonic area were studied. • The pore formation process and its evolution were discussed. • The reservoir physical properties of favorable shale reservoirs were summarized. [ABSTRACT FROM AUTHOR]