In thick coal seam conditions, the surrounding rock deformation in the longwall mining faces’ along-the-goal roadway is severe, and the support strength struggles to meet roadway retention requirements. A coordinated control strategy, termed “pressure-relief and support,” is proposed, which includes an “Optimization of Roof Cutting in Surrounding Rock Structure, Reinforcement of surrounding rock support, high-strength temporary support, and roadside gangue-blocking support.” A numerical model for roof-cutting pressure relief in thick-seam caving mining gob-side entries was established to simulate various roof-cutting heights and angles. This model analyzes the evolution patterns of stress and displacement under different cutting parameters to identify optimal values. The study presents a coordinated “pressure-relief and support” control scheme for gob-side entries in thick-seam caving mining, with its feasibility validated through numerical simulation analysis and field industrial tests. The findings demonstrate that the selection of the roof-cutting height and angle exerts a significant influence on the deformation behavior of the retained roadway roof. By severing the roof strata, this technique disrupts the load-transfer path from the goaf to the entry, thereby mitigating the adverse effects of overlying strata fracturing and facilitating more effective ground control. As a result, roof-cutting and pressure relief substantially reduce the stress imposed on the supporting structures. The coordinated “pressure-relief & support” control strategy employed in gob-side entry retaining for thick-seam longwall top-coal caving faces notably improves the surrounding rock stress regime and effectively restrains roadway convergence.

This study addresses the major engineering challenges of leaving roadways along the goaf in shallow-buried coal seam tunnels through water-bearing soft rock. It focuses on three core issues: the mechanism of rock mass softening upon water exposure, large-deformation control, and directional pressure relief technology. By integrating laboratory testing, theoretical analysis, numerical simulation, and field testing methods, the evolution of macro- and micro-mechanical properties of rock under water–rock interaction can be studied. The research developed constant-resistance large-deformation rock bolts with “yielding within resistance and resisting within yielding” characteristics, revealed the mechanism of directional fracturing through shaped charge blasting, and proposed a synergistic control technology for along-the-goal rib retention: “shaped charge blasting for roof fracturing and pressure relief + reinforced rib support + debris retention devices.” Research findings indicate: increased sandstone water content triggers dissolution of calcareous cement and expansion of clay minerals, leading to rock strength degradation and accelerated deformation, yet the failure mode remains uniaxial shear failure. The developed constant-resistance large-deformation anchor core device maintains a stable working resistance of approximately 350 kN within a 396–405 mm tensile deformation range, significantly enhancing the support system’s crack-resistant capacity under pressure. The focused jet directs cracks to penetrate along predetermined paths, forming planar damage zones and effectively suppressing vertical damage to the surrounding rock. Based on field monitoring, the tunnel was divided into advance support zones, temporary support zones, and stable tunnel sections, enabling a differentiated support scheme. The engineering application achieved stable tunnel retention and safe reuse. This study provides key theoretical foundations and technical approaches for controlling rock mass stability in similar tunnel conditions.

To investigate the mechanical properties of concrete-foamed cement composite specimens (C-FCCS), uniaxial compression tests were conducted on composite specimens with varying proportions and strengths of foamed cement. The analysis focused on the peak compressive strength, peak strain, macroscopic failure morphology, and acoustic emission (AE) characteristics of C-FCCS. The experimental results indicate that the peak compressive strength of C-FCCS exhibits a negative correlation with the proportion of foamed cement and a positive correlation with the proportion of concrete. At foamed cement proportions of 10% and 20%, the peak compressive strength of C-FCCS is predominantly governed by concrete, with AE energy concentrated primarily during the initial loading phase and near the peak stress. In contrast, at foamed cement proportions ranging from 30 to 50%, the peak compressive strength is dominated by foamed cement, with AE energy concentrated around the peak stress. The peak strain of C-FCCS shows a trend of initially increasing and then decreasing with the increase in height ratio (Height ratio = Foamed cement height/C-FCCS height). Under different height ratios, the peak strain of C-FCCS is approximately 175.61–558.13% of that of pure concrete specimens. Furthermore, variations in the strength of foamed cement have a minimal impact on the peak compressive strength of C-FCCS but significantly affect the peak strain. The peak compressive strength of C-FCCS is about 77.67–83.87% of that of pure concrete specimens, while the peak strain ranges from 128.46 to 361.38%. Lastly, the macroscopic failure of C-FCCS is primarily characterized by tensile failure, with shear failure commonly observed at the edges and corner interfaces of C-FCCS.