Due to the unique nature of the coal mining industry, safety is always one highly upheld premise of high production and high efficiency. According to the stress adjustment characteristics of the surrounding rocks in roadway excavation under a nondisruptive environment, the stress paths of unloading confining pressure and loading axial pressure were designed creatively and vividly, and the coal mechanical properties and energy evolution law under different loading axial pressure rates were studied through a series of experiments. As the loading axial pressure rate increases, the mechanical parameters at the time of coal failure show a nonlinear increase in the peak strength, the confining pressure, and the axial strain, while the variation laws of lateral strain and volumetric strain are not obvious. In addition, the failure mode transfers from the brittle failure to the ductile failure. In terms of energy, the positive work done by the axial pressure, the total work, and the elastic strain energy tend to increase nonlinearly, while the negative work done by the confining pressure and the plastic strain energy increase conversely. The elastic strain energy conversion rate increases logarithmically, indicating that a higher loading axial pressure rate tends to increase the probability and strength of coal instantaneous failure and subsequent dynamic behaviors. The research results reveal that providing an appropriate pressure relief and timely support after the roadway excavation in the actual production process can effectively reduce the energy level of the environment at the location of the surrounding rock support system, which is conducive to the roadway support and the surrounding rock stability control. Furtherly, it has important reference value for the roadway excavation and other underground engineering excavation and support operations and is of great significance to promote the development of deep resources.

In order to maintain the long-term dynamic stability of gravel soil subgrade under traffic loading and prevent fatigue damage, it is necessary to determine the long-term dynamic strength of gravel soil under different working conditions. The dynamic triaxial test was carried out on the 40 groups of remolded gravel soil samples under chosen 8 working conditions. Based on the results of the dynamic triaxial test, the εp-N curves and εp-lgN curves were drawn. Further, the σd-lgNf curves of gravel soil were drawn, and finally, the long-term dynamic strength computation model of gravel soil was established. The effects of confining pressure, water content, degree of compaction, loading frequency, and initial static deviatory stress on the long-term dynamic strength of gravel soil were also analyzed. It is concluded that With the increase of confining pressure and compaction degree, the long-term dynamic strength of increases. With the increase of the number of loading cycles and initial static deviatory stress, the long-term dynamic strength decreases. At the optimal water content, the long-term dynamic strength is the highest. And the impact of loading frequency on the long-term dynamic strength is relatively small. The relationship between the long-term dynamic strength under 1 ×106，5 × 106 and 1 ×107 loading cycles of gravel soil and the resilient modulus was established, and the value of the relationship curve coefficient ranges from 0.885 to 1.945.

Precast slab parameters are important factors affecting the mechanical performance and service life of precast-slab-fabricated recyclable roads. To clarify the force mechanism of recyclable precast-slab-fabricated roads and provide a basis for selecting slab parameters, a field test of a recyclable road fabricated using a large-scale precast slab was conducted in this study. The horizontal and vertical stresses on the top and bottom surfaces of the precast slab are determined. The stress-time history curves show that the horizontal and vertical stresses have peak values corresponding to the time at which the axle acts directly on the precast slab. Based on the arching effect theory, the mechanical mechanism of a precast-slab-fabricated recyclable road was analyzed. Owing to the arching effect between the precast slabs, they were cooperatively stressed. Compared with precast slab bearing vehicle load independently, When the arch effect works, both the maximum horizontal stress and the vertical stress decrease. According to the field test results, the influence laws of the material, size, thickness, and shape of the precast slab on precast slab stress were obtained. In order to achieve maximum service life and road performance of recyclable Precast-Slab-Fabricated road, the characteristic parameters of the precast slab are suggested as follows. The grade of concrete used for the precast slab should be more than C30, the size of precast slab can be 2m, large thickness of precast slab should be used(e.g.0.2m), and square precast slab with width-length ratio of 1 should be adopted as far as possible.