Deep learning based semantic communication (DLSC) systems have shown great potential of making wireless networks significantly more efficient by only transmitting the semantics of the data. However, the open nature of wireless channel and fragileness of neural models cause DLSC systems extremely vulnerable to various attacks. Traditional wireless physical layer key (PLK), which relies on reciprocal channel and randomness characteristics between two legitimate users, holds the promise of securing DLSC. The main challenge lies in generating secret keys in the static environment with ultra-low/zero rate. Different from prior efforts that use relays or reconfigurable intelligent surfaces (RIS) to manipulate wireless channels, this paper proposes a novel physical layer semantic encryption scheme by exploring the randomness of bilingual evaluation understudy (BLEU) scores in the field of machine translation, and additionally presents a novel semantic obfuscation mechanism to provide further physical layer protections. Specifically, 1) we calculate the BLEU scores and corresponding weights of the DLSC system. Then, we generate semantic keys (SKey) by feeding the weighted sum of the scores into a hash function. 2) Equipped with the SKey, our proposed subcarrier obfuscation is able to further secure semantic communications with a dynamic dummy data insertion mechanism. Experiments show the effectiveness of our method, especially in the static wireless environment.

The compaction characteristics and bearing capacity of dry filling materials in goaf have a significant influence on stope control and surface stability. Through acoustic emission monitoring and mechanical model analysis, a series of confined compression tests were conducted on crushed waste with varying particle sizes and Talbot coefficients. The deformation, fragmentation, and acoustic emission characteristics under corresponding working conditions were determined. The results indicate that the stress–strain curves of crushed stone with different particle sizes and Talbot coefficients exhibit similar nonlinear behavior during confined compression. However, the strain response varies with changing stress levels. By analyzing the slope change rate of the stress–strain curve, the lateral uniaxial compression process of waste rock can be divided into three deformation stages: rapid compression, stable crushing, and slow compaction. The compressive deformation characteristics of gravel differ based on particle size and Talbot coefficient. Specimens with a higher Talbot coefficient demonstrate stronger compressive resistance and weaker deformation resistance during initial compaction loading. Notably, the internal pressure structure strength is influenced by factors such as maximum particle size D, grading coefficient n, and particle size distribution continuity, rather than solely by the proportion of large particles. The evolution of acoustic emission signals and energy-time curve during waste rock confined axial compression synchronizes with the compaction process. Overall, compaction plays a critical role in maintaining the stability of goaf in dry crushed waste filling.

Rock burst is easy to occur in the water-rich roadway of coal mines, which is closely related to the energy dissipation and fracture mechanism of rocks under coupled hydro-mechanical (H-M) unloading. Therefore, in combination with the triaxial loading and unloading process and H-M coupling effect, the mechanical test of layered sandstones under coupled hydro-mechanical unloading (TLUTP) was conducted. The energy dissipation and fracture mechanism were revealed. The results show that: (1) The influence of layered angles on the peak volumetric strain is more sensitive than that of confining pressure under conventional triaxial loading with H-M coupling (CTLTP). On the contrary, the influence of confining pressure on the peak volumetric strain is more sensitive than that of layered angles under TLUTP. (2) With increasing layered angles, the peak elastic energy density under CTLTP shows the “W” shaped evolution characteristic, while that of under TLUTP shows the “N” shaped evolution characteristic. (3) The “Energy Flow” chain is proposed. Meanwhile, combined with the domino effect and the structural evolution theory, the energy dissipation and fracture mechanism of layered sandstones under coupled hydro-mechanical unloading are both revealed. The conclusions obtained can provide certain fundamental theoretical references for the effective prevention of rock burst in a layered water-rich roadway.

To address the challenges posed by complex regional stress and the maintenance of surrounding rock in soft rock roadways subjected to strong dynamic pressure crushing during excavation, this study focuses on the 1570 track stone gate of Daniuchang Coal Mine in Guizhou Province as the engineering context. A comprehensive research approach was employed, utilizing numerical simulations, theoretical analyses, and on-site industrial tests. Through on-site investigations and data monitoring, we analyzed the large deformation of the surrounding rock at Shimen on the 1570 track and the failure characteristics of the supporting components. The poor self-stability of the surrounding rock was investigated using water immersion tests (combined with XRD analysis) and loose ring tests. Numerical simulations were conducted to elucidate the stress distribution patterns during the excavation of the 1570 track stone gate, revealing its deformation and failure mechanisms. We specifically proposed a full-space collaborative support technology for the reconstructed multi-bearing structure. The ultimate bearing stress of the most critical section of the concrete steel arch frame was derived through theoretical analysis, confirming that the constrained steel pipe filling structure could effectively limit the significant structural movements induced by mining activities. The stress distribution and deformation control effects of the surrounding rock in the reconstructed multi-bearing structure were analyzed through numerical simulations, clarifying the control principles underlying the full-space cooperative support technology. By constructing a three-layer high-strength load-bearing structure, we integrated the shallow and deep surrounding rocks into a cohesive high-strength anchor solid load-bearing system. This approach harnesses the surrounding rock′s inherent load-bearing capacity and enhances the overall anti-deformation capability of the surrounding rock, thereby establishing a full-space three-dimensional support system that ensures roadway stability. Subsequent industrial tests conducted underground demonstrated that the full-space collaborative support technology for multi-bearing structures significantly mitigates deformation in roadways facing strong dynamic pressure crushing and soft surrounding rock. Compared to the original support system, the convergence of the top and bottom slabs of the roadway, as well as the two sides, was reduced by 91.67% and 88.33%, respectively. Additionally, this approach led to savings in roadway maintenance costs, providing an effective solution for managing surrounding rock in soft rock roadways subjected to strong dynamic pressure crushing.