The use of fiber Bragg grating (FBG) sensors is proposed to solve the technical problem of poor sensor stability in the long-term safety monitoring of shaft lining structures. The auxiliary shaft of the Zhuxianzhuang coal mine was considered as the engineering background, and a test system implementing FBG sensors was established to monitor the long-term safety of the shaft lining structure. Indoor simulation testing revealed that the coefficient of determination (r²) between the test curves of the FBG sensor and the resistance strain gauge is greater than 0.99 in both the transverse and vertical strains. Therefore, the FBG sensor and resistance strain gauge test values are similar, and the error is small. The early warning value was obtained by calculation, according to the specific engineering geological conditions and shaft lining structure. The monitoring data obtained for the shaft lining at three test levels over more than three years reveal that the measured vertical strain value is less than the warning value, indicating that the shaft lining structure is currently in a safe state. The analysis of the monitoring data reveals that the vertical strain increment caused by the vertical additional force is approximately 0.0752 με/d. As the mine drainage progresses, the increasing vertical additional force acting on the shaft lining will compromise the safety of the shaft lining structure. Therefore, the monitoring must be enhanced to facilitate decision-making for safe shaft operation.

During the construction of coal mine shafts through Cretaceous water-rich stratum using the freezing method, the frozen shaft lining can break and lose stability. Hence, it is necessary to examine the mechanical properties and constitutive relationship of Cretaceous water-rich sandstone under the effect of surrounding rocks. To this end, in this work, the mechanical properties of red sandstone at different confining pressures and freezing temperatures were examined by using a ZTCR-2000 low-temperature triaxial testing system, wherein the 415–418 m deep red sandstone in the Lijiagou air-return shaft of Wenjiapo Mine was taken as the research object. The test results indicated that the stress–strain curves of rock under triaxial compression and uniaxial compression presented four stages: pore compaction, elastic compression, plastic yield, and post-peak deformation. The difference between the two cases was that the post-peak curve of the former was abrupt, while the latter exhibited a post-peak strain softening section. As the freezing temperature was constant, with the raise in the confining pressure, the elastic modulus and peak strength of the rock rose linearly, while the Poisson’s ratio decreased quadratically. As the control confining pressure was constant, the elastic modulus and rock’s peak strength increased with the decrease in the temperature, and under the condition of negative temperature, the two parameters were linearly correlated with the temperature, while the Poisson’s ratio showed the opposite trend. The two-part Hooke’s model and the statistical damage model based on Drucker–Prager (D-P) yield criterion were used to establish the stress–strain relationship models before and after the rock yield point, optimize the model parameters, and optimize the junction of the two models. The results revealed that the optimized model curve was in good agreement with the experimental curve, which suggests that the proposed model can accurately describe the stress–strain characteristics of rock under three-dimensional stress. This verified the feasibility and rationality of the proposed model for examining the constitutive relationship of rocks.

Metakaolin has been incorporated into high-performance fiber-reinforced concrete for wellbore wall drilling to enhance its durability in strata with highly mineralized water. This study established a benchmark, utilizing fly ash, slag powder, and metakaolin as the factors in an orthogonal test to assess the durability of concrete against sulfate attack. The range analysis and an integrated balance method were employed to optimize the mix proportion, the optimized mix proportion of high-performance concrete was determined as concrete: cement: fly ash: slag powder: metakaolin: pumping agents: gravel: sand: water: polyvinyl alcohol = 1: 0.2: 0.075: 0.05: 0.106: 2.767: 1.556: 0.371: 0.003. The apparent and microscopic morphologies before and after the erosion of both the benchmark group and optimized mix proportion group were investigated. The triaxial permeability tests were conducted on these groups under varying confining pressures to elucidate concrete permeability trends. Additionally, a damage constitutive model for concrete under a sulfate attack was formulated based on the durability tests. This study could provide valuable insights into the industrial utilization of concrete in deep shafts within highly mineralized water strata in Northwestern China.