Roadway floor rock burst is an important manifestation of rock bursts in deeply buried mines. With the increase of mining depth and mining intensity, rock burst disasters in the roadway floor such as floor heaves are becoming more serious. The article investigated the roadway floor severe heave caused by floor rock burst during excavation of the No. 3401 working face, which was controlled by an anticlinal structure and deep mining in Shandong Mine, China. Firstly, by analyzing geological conditions of the working face, roadway support parameters, and characteristics of coal and rock, it was revealed that high tectonic stress and high crustal stress were main causes of the floor rock burst. Secondly, based on the Theory of Mechanics and Theory of Energy, the energy conversion process in the roadway floor was discussed, and the rock burst condition caused by elastic energy in the roadway floor was analyzed. The failure characteristics of roadway-surrounding rock were also inspected, using a borehole recorder. The roof and sidewalls of roadway mainly contained fissures and cracks, whereas cracks and broken areas are distributed in the roadway floor. Finally, based on the deformation and failure characteristics of roadway-surrounding rock, a method termed “overbreaking-bolting and grouting-backfill” was proposed to control roadway floor rock burst. The method was tested in the field, and the results showed that it could effectively control the deformation of roadway floor and rock burst, guaranteeing the stability of roadway floor. This impact control method for the roadway floor can provide a reference for the prevention and control of roadway rock burst in mines with similar geological conditions.

In blasting operation, some undesirable impacts, such as fly-rock, fragmentation, and back break, are induced. If the blasting design is not optimized, these mentioned impacts would reduce the blasting efficiency. To improve and optimize the blast design, blasting effect evaluation is essential. Due to the complexity of interactions among blasting parameters, empirical methods may not be appropriate for blast design optimization. A two-level mathematical model based on fuzzy mathematics, is proposed in this work. In total, 11 typical parameters were chosen and classified into three groups. The blasting effect is evaluated from three aspects, and then the comprehensive evaluation is given. A blasting effect evaluation system was developed based on the mentioned method on the platform of VC++. Some other techniques, such as image processing, were integrated into the system, which allowed for obtaining all of the parameters rapidly and conveniently. The system was applied in practical bench blast engineering. The results obtained from the system can provide effective information for the optimization of the next blast design.

Reinforced concrete (RC) slab is an important component in civil construction and protection engineering, and its dynamic response under impact loading is a complex mechanical problem, especially for two or multiple continuous impact loads. In this paper, a series of drop hammer impact tests were carried out to investigate the dynamic response of RC slabs with two successive impacts. The time history of impact force and the failure characteristic of the slab surface were recorded. Moreover, four influence factors, including slab thickness, reinforcement ratio, impact location, and drop hammer height have been discussed. Besides, a 3D numerical model based on the finite element method (FEM) was established to expand the research of constrained force, deflection, and vertical stress of an RC slab. The results show that increasing the slab thickness and reinforcement ratio can improve the impact resistance of an RC slab. The impact point location and drop hammer height have a great influence on the dynamic response of the RC slab. In addition, the RC slab will have more obvious damage under the second impact, but the dynamic response becomes weaker. It may be because of the local damage in the concrete caused by the first impact that would weaken the propagation of vibration.

Stress concentration caused by tectonic stress and mining disturbance in coal mines induces a unique type of rock burst. No. 3201 working face controlled by an anticline structure in the Shandong mining area is used as the research background. The formation mechanism for anticlines is analyzed. Theoretical research shows that the bigger the tectonic couple is, the smaller the foundation stiffness, and the greater the bending degree and elastic strain energy of the coal will be. The distribution characteristics of abutment pressure and maximum principle stress in anticlinal control areas are analyzed using UDEC numerical software. The results show that rock bursts result from interactions between abutment pressure and residual tectonic stress. The “connection-overlay-separation” phenomenon of abutment pressure presents with working face advancement. Furthermore, the energy criterion for rock burst initiation is established based on the energy principle. Residual energy “E0−EC” and rock burst danger characteristics during mining are discussed. Based on the simulation results, microseismic monitoring data for No. 3201 working face are analyzed, and the law of microseismic energy is consistent with the variation law for the residual energy “E0−EC” at the peak of the simulated abutment pressure. The microseismic energy and frequency are higher during mining, increasing the risk of rock burst events. It can provide scientific basis for prevention and control of rock burst.

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