Aiming at the support problem of large deformation of surrounding rock in deep high ground stress roadway, a kind of compressible concrete-filled steel tube support structure (referred to as "compressible support") was proposed. Firstly, a comparison test of compressible similar materials was carried out, and PVC foam was determined to be applicable as the compressible similar material for simulation tests. Secondly, the similar simulation test of the compressible support was carried out, and the stress-time and load-displacement curves of the whole process of static load were obtained. The evolution of compressible support, initiation and propagation of concrete cracks was monitored. Three mechanical response stages of the compressible support were revealed: the elastic deformation stage, stable yielding stage and rigid stage after yielding. The test results show that the peak stress of the surrounding rock of the roof and floor is approximately 0.7 MPa, and the peak stress of the surrounding rock of the left and right sides is approximately 1.4 MPa. The stress of the surrounding rock is transferred to the depth, the supporting model does not experience overall instability and deformation, and the support is bent, but the structure is still intact. The compressibility of PVC foam measured is approximately 77%, indicating that the support achieves a favorable yielding effect. The field application results show that the maximum displacement of the roof and floor of the surrounding rock is 216 mm, and the compressibility of the compressible support is about 72%. The compressible support achieves favorable supporting performance, and the support structure can effectively coordinate the collaborative deformation of the surrounding rock and support. The research results can provide reference for the support design and engineering application of the compressible support.

To promote the resource utilization of industrial solid waste and the sustainable development of green wet-mix shotcrete, cement clinker-free solid-waste-based wet-mix shotcrete was prepared using steel slag, slag, and desulfurization gypsum as cementitious materials, and copper slag and waste rock as aggregates. Furthermore, raw material property analysis, mix proportion optimization, mechanical property testing, microscopic mechanism investigation, and on-site industrial tests were systematically conducted. The results indicate that the mechanical properties of the solid-waste-based wet-mix shotcrete with optimal mix proportions (specimens No.5 and No.9) are superior to those of the cement-based wet-mix shotcrete. The 7-day compressive strength of specimen No.9 reaches 16.31 MPa, and its 56-day compressive strength exceeds 28 MPa. Its workability is comparable to that of the cement-based wet-mix shotcrete, and the slump and slump flow meet the requirements of wet spraying operations. The solid-waste-based wet-mix shotcrete exhibits a remarkable solidification effect on heavy metals. It reduces the leaching concentrations of excessive heavy metals Pb and Cd in the copper slag to below the Class Ⅱ water quality standard for groundwater, demonstrating excellent environmental safety. Microscopic analysis results indicate that the solid-waste-based wet-mix shotcrete is rich in hydration products and exhibits a high degree of polymerization of the silicate gel. On-site tests verify the feasibility of engineering application for the copper slag wet-mix shotcrete. Although issues such as incomplete material discharge exist, they can be improved through process optimization. This provides an effective path for the harmless disposal and resource utilization of solid wastes such as copper slag, possessing environmental, economic, and social values.

Underground rock masses often contain fissures with different inclination angles and various fillings, and the crack propagation and failure behavior of rock bridge structures directly affect the stability of underground rock engineering. Through uniaxial compression tests on filled jointed red sandstone with different inclination angles, acoustic emission parameters (ring count, rise time, amplitude, duration) monitoring and FRACOD numerical simulation, the crack propagation law and damage mechanism of rock bridge structures in filled joints under different inclination angles of joint were systematically studied. The results show that the stress-strain curves exhibit three stages of compaction, elastic deformation and rapid stress drop. A stress surge occurs near the peak stress due to specimen slip and crack initiation. The acoustic emission signals increase significantly before and after the peak stress. The cumulative ring count shows a stepwise jump, and the abrupt increase points of its curve can effectively determine the critical point of crack initiation. The results of RA-AF analysis show that the proportion of shear cracks is the largest when inclination angle of joint is 30°, and tensile failure dominates when inclination angle of joint is 45°. With the increase of inclination angle of joint, the crack propagation mode transforms from tensile-dominated to tensile-shear composite, and then back to tensile-dominated. The FRACOD simulation results show that with the decrease of stress ratio, the horizontal stress significantly restrains the initiation and propagation range of cracks. The increase in horizontal stress significantly changes the failure mode of the rock mass by inhibiting the propagation of tensile cracks. The results reveal the mechanism of joint inclination angle on crack propagation and damage evolution of rock bridge structures, providing a theoretical basis for stability analysis of deep underground rock engineering.

In high-altitude cold regions, complex physicochemical processes such as water-ice phase transitions, ice wedging, and filler dissolution/crystallization occur within rocks, which can easily lead to irreversible damage in rocks with filling fractures, seriously threatening the safety and stability of open-pit mine slopes and transportation infrastructure in these regions. Taking frozen sandstone with filling fractures (FSFF) as the research object, the acousto-optic combined testing technique was employed to investigate the effects of fracture length and fracture angle on the macroscopic mechanical properties, surface strain field, and acoustic emission (AE) parameters of the rock samples. The results show that as the fracture length increases, the compressive strength of the rock samples exhibits a continuously decreasing trend, and the crack propagation in the rock samples is dominated by S1 and S3 type shear cracks and M type tensile-shear mixed cracks. When the fracture length is short, the sharp increase in the AE ring count of the rock samples is concentrated in the crack propagation stage. As the fracture length increases, the phenomenon of the sharp increase in the ring count extends to the elastic stage and the crack propagation stage. With the increase in the fracture angle, the compressive strength of the rock samples first decreases and then increases. The number of sharp increase events in the AE ring count within the rock samples increases, and the spatial distribution of AE events becomes increasingly dispersed. The crack propagation in the rock samples is dominated by S1, S2, and S3 type shear cracks and M type tensile-shear mixed cracks. The failure mode of FSFF is primarily shear rupture. The lower the compressive strength of the rock sample, the greater the proportion of internal shear cracks. The research results can provide a theoretical basis for the engineering stability assessment of fractured rock masses in cold regions.

To reveal the tensile fracture and instability collapse mechanism of granite roofs in deep mining, three types of samples, namely fine-grained Luotian granite, coarse-grained Golden Ma granite, and medium-grained Yunfu granite, were selected for three-point bending tests. Combined with acoustic emission monitoring technology, the bending strength, dominant frequency distribution, damage evolution, and crack propagation patterns were systematically investigated. The results show that the bending strength of granite exhibits a significant particle size effect. The fine-grained Luotian granite has the highest strength of 17.79 MPa, with a sudden post-peak stress drop indicating brittle fracture. The coarse-grained Golden Ma granite has the lowest strength of 5.33 MPa, showing pronounced ductility characteristics. The strength of medium-grained Yunfu granite lies between the above two rock types, reaching 16.04 MPa, and exhibits brittle-ductile transition behavior after the peak. The dominant frequency signals of acoustic emission mainly appear near the peak load and in the post-peak stage, forming three main frequency bands of 0-40 kHz, 50-80 kHz, and 130-180 kHz. The high-frequency signals (130-180 kHz) of Luotian granite surge before the peak, while the dominant frequencies of Golden Ma granite and Yunfu granite are concentrated in the low-frequency band (0-40 kHz) after the peak. The damage evolution of granite undergoes three stages: initial damage, stable development, and accelerated development. Damage accumulation is highly concentrated in the post-peak stage. Golden Ma granite has the highest damage proportion in the post-peak stage, and Luotian granite releases the largest strain energy per unit damage. RA-AF crack mode analysis indicates that the failure of the samples is dominated by tensile cracks, and the proportion of tensile cracks is negatively correlated with mineral grain size. The proportion of tensile cracks in Luotian granite is 3.17 and 6.15 percentage points higher than that in Yunfu and Golden Ma granite, respectively. The quantitative early warning method for roof instability based on dominant frequency signals can provide a theoretical basis and engineering guidance for roof stability evaluation and dynamic disaster prevention and control in deep mining.

In order to investigate the mechanical properties and permeability evolution of limestone with parallel double fissures during complete stress-strain processes before and after grouting, the complete stress-strain seepage tests was carried out on limestone with 45° parallel double fissures before and after grouting under the confining pressure of 10 MPa, 20 MPa and 30 MPa. The test results show that the strength of limestone with parallel double fissures before and after grouting increases nonlinearly with the increase of confining pressure, but the permeability decreases with the increase of confining pressure. Under the same confining pressure conditions, the strength of the specimens after grouting is significantly improved compared with that before grouting. Before grouting, the permeability of parallel double fissures specimens showed a "double peak" phenomenon. After grouting, the grout filled the cracks of the specimens, enhanced the bonding force between the fissure surfaces, changed the geometric shape and mechanical properties of the fissures, thus reducing the occurrence of "double peak" phenomenon. Compared with the specimens before grouting, the pre-peak permeability of the specimens after grouting decreased slightly, but the post-peak permeability decreased significantly. The five key permeability values of the two types of specimens gradually decrease with the increase of confining pressure. Under the same confining pressure, the key permeability values of the specimens after grouting are significantly lower than those of the ungrouted specimens.

The "double carbon" goal puts forward the dual requirements of low-carbon transformation and ecological protection for the sustainable development of open-pit coal mines. Geological disaster prevention and mining area ecological restoration as its core issues need to adapt to new development needs. In view of the contradiction between energy security and low-carbon development faced by open-pit coal mines under the goal of "double carbon", the research progress of geological disaster prevention and ecological restoration was systematically discussed. In the field of geological disaster prevention, the evolution of traditional disaster characteristics and the emergence of new disasters under low-carbon orientation were analyzed, and the application results of energy-saving monitoring technology, carbon footprint-oriented early warning model and green support technology were sorted out. In terms of ecological restoration, the development status of carbon sink function research, low-carbon ecological restoration technology and carbon sink evaluation method of vegetation-soil system were summarized. On this basis, the existing problems such as technical bottlenecks (conflict between traditional technology and low-carbon goals, difficulty in collaborative carbon sink efficiency and engineering stability, insufficient technology integration, etc.), lack of management mechanism (cross departmental policy barriers, ambiguous rights and responsibilities of stakeholders, lack of regional collaborative, etc.) and insufficient policy support (fragmented policy system, disconnection in standard coordination, imperfect incentive and restraint mechanisms, etc.) were further analyzed. Finally, the three transformation paths of technology (building a low-carbon collaborative technology system), management (establishing a carbon-oriented collaborative mechanism) and policy (improving the low-carbon support and guarantee system) were prospected, which provides a theoretical reference for the collaborative development of "disaster prevention-promoting restoration-carbon sink" in open-pit coal mines.

Inclined shaft hoisting conveyances are characterized by heavy payloads and high operating speeds, which generate tremendous impact forces upon braking during a runaway event. However, existing runaway protection devices primarily rely on passive safety facilities within the shaft for interception. They are unable to adapt to the dynamic variations in impact energy, failing to achieve effective energy absorption. To address this issue, a design and optimization method for an adaptive multi-stage buffered inclined shaft hoisting conveyance was proposed, aiming to achieve mechanical braking and the staged absorption of impact energy following a runaway event. Based on this structure, a multi-body coupled impact dynamics model of the multi-stage buffered hoisting conveyance and the inclined track was established. The effect of multi-stage buffering on the braking impact force of the hoisting conveyance system was investigated, and the stiffness of the buffer springs was optimized based on the Sequential Quadratic Programming (SQP) algorithm. The results indicate that, compared with the unbuffered structure, the multi-stage buffered structure reduces the impact force by 24.5%, significantly decreasing the impact response, presenting smaller residual oscillations, and yielding a smoother curve. After the spring stiffness is optimized by the SQP algorithm, the impact force of the hoisting conveyance and inclined track system decreases by 35.5% and 14.7% respectively, compared to the unbuffered system and the pre-optimization multi-stage buffered system. This improves the absorption efficiency of impact energy, enhances the system's impact performance, and results in a more stable secondary impact force. The research findings provide a theoretical basis for the impact-resistant design and safe braking strategies of inclined shaft hoisting conveyances.

To address the challenges of insufficient mobility of traditional stationary oxygen stations and the limited operational duration of portable equipment such as carbon fiber oxygen cylinders and oxygen bags in high-altitude areas, a novel emergency air respirators was developed. The apparatus adopted intelligent mixed oxygen supply technology and integrated a spiral oxygen-nitrogen separator. It effectively reduced the overall volume while improving the gas separation efficiency, achieved highly efficient oxygen-nitrogen separation, and continuously and stably provided breathing gas with an oxygen concentration of 21%. Tailored for complex operating conditions such as low pressure and low temperature in high-altitude regions, the system overcame the shortcoming of insufficient operational duration of traditional equipment through integrated and optimized design. The test results indicate that under the high-altitude condition of 5 445 m, after adopting the novel emergency air respirators, the blood oxygen saturation of users increases from a dangerous level of approximately 68% to a relatively safe level of 92%. The maximum battery duration reaches (296±6) min (altitude -154 m), and the apparatus possesses advantages such as high oxygen production efficiency, rapid response, easy operation, as well as safety and energy conservation. The research results provide a more reliable safety guarantee for emergency rescue and underground operations in high-altitude mining areas.

The rapid development of autonomous driving technology has continuously expanded its application scenarios, and unmanned driving in mines has become an important direction in intelligent mine construction. Aiming at the problems of complex underground working environments, high manual labor intensity, and prominent safety risks, an unmanned driving system for underground electric Load-Haul-Dump (LHD) machines was designed and implemented by integrating autonomous driving and remote control technologies. The system adopted an operation mode of "remote-controlled loading, autonomous driving for transportation and unloading", realizing the full-process unmanned operation of LHD machines in underground roadway environments. Field industrial test results show that the average lateral tracking error of the system during operation is controlled within 0.30 m, the positioning loss probability is approximately 0.11%, and the average communication latency is less than 5 ms. The system also possesses good safety assurance capabilities, with the access control system and anti-collision detection module effectively handling emergency situations. The research results verify the stability and practicability of the system in underground mine environments, which can effectively reduce miners'labor intensity and improve underground working conditions.