The acoustic emission b value is an important and widely used parameter for the early prediction of rock fractures. In this study, five groups of true triaxial compression tests were conducted on granite specimens to analyze changes in b value during the process of rock failure, and to investigate the b value characteristics of acoustic emission events. First, the acoustic emission events that simultaneously triggered at least four sensors were located using P-wave arrivals and sensor coordinates. Then, considering various intervals of acoustic emission event counts, stress magnitude, and stress proportion, b values were calculated using the values of the maximum amplitude, average amplitude, maximum absolute energy, and average absolute energy of the acoustic emission events. In addition, the goodness of the fitting curves was used to evaluate the fitting reliability of the b values. The results indicated higher accuracy of b value when calculated using the average amplitude setting for intervals of acoustic emission event counts of 200 or greater, stress magnitude of 20 MPa or greater, and stress proportion of 10% or greater. Moreover, the interval of event counts of 200 is suggested as a window parameter for b value calculations, and the b values are observed to exhibit a decreasing trend before fracture for more than 80% of the specimens. Furthermore, the b value tends to decrease with an increase in confining pressure. Thus, the b value can be used as an indicator for validating the stress concentration area, including magnitudes and accumulative probability density distribution of events, which is a beneficial complement to clarifying precursor information of rock mass instability.

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Most of the existing research on cement slurry materials are not environmentally friendly and environmental pollution is significant. Most researchers only test its performance, but do not conduct engineering feasibility verification. In this study, the materials extracted from various wastes were used to replace part of the sulfoaluminate cement, and orthogonal experiments were designed to analyze the reaction mechanism between different materials. Finally, the optimal mixing ratio was obtained. Then, through the regression equation analysis method, digital photograph restoration technology, the finite element method and various practical engineering conditions, the feasibility of the slurry under different applicable engineering conditions was compared and analyzed. The comparison between the experimental and numerical simulation results shows that the cement slurry obtained in this study has good reliability and feasibility. It can carry out rapid grouting reinforcement. The results of this study not only provide a feasible and environmentally friendly cement slurry for a wide range of construction projects, but also provide an effective method for the treatment of various wastes.

In order to verify the applicability of the computer numerical simulation method under complex engineering conditions, and solve the problem that it is difficult to guarantee the normal construction of underground projects with a depth of more than 1 km (it is difficult to carry out multiple field attempts under highdepth conditions, and if you simply use ordinary the calculation method, its calculation accuracy is difficult to guarantee). For the construction of complex geological conditions of an underground mine with a depth of 1300 m in the Central Plains of China, based on the finite difference method (FDM) with high calculation accuracy, using FLAC 3D software based on FDM, and using progressive design method (PDM) [1], design a variety of different schemes and analyze the mechanism of force and deformation of the surrounding rock mass of the project. Apply the obtained optimal scheme in actual engineering, and monitor the actual force and deformation. Comparing the results of the computer numerical simulation with the monitoring results, the results show that the computer numerical simulation method can also have good application in the actual engineering under the geological conditions of ultra-kilometer depth. It also provides theoretical basis and technical guidance for engineering hypothesis under approximate conditions.