In longwall top coal caving (LTCC), due to the fracture and migration of top coal, the roof will break and collapse, which causes serious impact damage to hydraulic support. Therefore, we aimed to reveal the relationship between the roof instability effect and the bearing characteristics of hydraulic support in the LTCC face. Based on the occurrence conditions of the 08 mining area in the Shilawusu Coal Mine, the instability model of the upper immediate roof was established, and the working resistance of hydraulic support was derived. Secondly, the dynamic coupling model of roof-top coal-hydraulic support was established in LS-DYNA, and the crushing degree of top coal and the bearing characteristics of the hydraulic support in different roof instability fields were analyzed. The results show that the main factors affecting the working resistance of hydraulic support are the fracture position of the upper immediate roof, the acting force of the lower immediate roof, and the distribution of the gangue in the goaf. The rotary instability of the upper immediate roof at the coal wall brings serious impact effects, resulting in fractures in front of the coal wall and a large amount of crushed coal concentrated at the front end of the canopy. The crushing degree of top coal significantly impacts the canopy, especially the back end of the canopy and the hinged pin shaft, which is prone to bending fracture. The research results can provide references and experience for the stability control of roof strata and the structural optimization of hydraulic support.

In the process of coal mining, the canopy and column play an important role in the safety support of hydraulic support. However, due to the complex and changeable coal seam conditions, the hydraulic support is significantly affected by the impact load. This paper aims to reveal the dynamic characteristics of canopy and column under impact load. Firstly, the dynamic model of hydraulic support is established, and the impact response of each hinge point of the canopy is analyzed. Secondly, based on the fluid–structure interaction (FSI) theory, the two-way FSI model of the column is established, and the structural change of the column and the flow field characteristics in the cylinder under the impact load are analyzed. The results show that the front column hinge is more prone to impact failure under impact load. The impact load has a significant impact on the two-level cylinder, the pressure in the cylinder increases, and an eddy current occurs on both sides of the bottom of the cylinder. The research results can provide references for the structural optimization of the hydraulic support with anti-impact load and the strength design of the column.

Top coal caving is an important way of thick coal seam mining. The current coal gangue identification technology is not mature, resulting in a low degree of automation of coal caving. The current numerical simulation pays little attention to the real shape of rocks. This paper aims to reveal the vibration response of the tail beam under the action of real shape coal gangue particles. First, the real shape rock and hydraulic support model are established, and the relationship between the Rock Mixed Ratio (RMR) and the vibration signal characteristics during the impact process are studied. The influence of falling velocity and coal strength on this relationship are analyzed. Finally, the influence of motion mode on this relationship is analyzed and discussed. The numerical results show that the increase of the RMR can significantly enhance the velocity and acceleration signals of the tail beam, and the signals caused by different RMR are still different under different velocities and strengths. The best recognition effect can be obtained when the coal gangue particles slip on the hydraulic support, and the effect is the the worst when the coal gangue particles impact upon and roll on the hydraulic support. The conclusion provides directions for further study of coal gangue identification based on vibration.

The broken top coal and gangue in the fully mechanized cave mining will be released from the rear of the hydraulic support in the form of bulk. In this process, the medium properties through the coal opening can be judged by monitoring the vibration signal on the tail beam. Based on the coupling method of the discrete element method (DEM) and the finite element method (FEM) in LS-DYNA, this article simulates the whole process of coal caving, establishes the finite element model of the tail beam of hydraulic support and the discrete element model of coal gangue particles, and analyzes the influence of coal caving step distance, mining and caving ratio, and pitching angle of the mining field on the application effect of the vibration identification method. The coal caving step distance has a great influence on the recognition effect, and some bottom coal should be appropriately sacrificed to reduce the gangue content. The application effect of the vibration identification method is good under different mining and caving ratios. Downward mining can cause gangue to be released in advance, making the recognizable signal lag behind the change of gangue content, while upward mining will lose a part of the coal, but the application of vibration recognition is better than downward mining.

Thin-walled structures have been extensively adopted as energy absorbers in various engineering fields. The energy accumulated in the coal and rock is released instantly, resulting in varying degrees of damage and failure to support equipment. To improve the crushing performance of underground support equipment, a metal thin-walled tube with high-bearing capacities is placed in the column as an energy-absorbing column. Based on the characteristics of non-dimensional parameters governing the crashworthiness of thin-walled tubes by the author’s team, a type of high-performance bi-tubular tube (HPBT) with mixed multicellular configurations is innovatively proposed. First, the finite element models of the HPBTs are established in LS-DYNA, and the accuracy of the FE model is verified by crushing tests. Second, the theoretical model of the mean crushing force (MCF) is derived. Moreover, the effects of the cross-sectional shapes and the wall thickness gradient distribution on the deformation modes and crashworthiness are investigated. The results show that the design strategies of the bi-tubular structures mixed multicellular configurations significantly improve the values of ω. The MCF of HPBT_C2 is 4458.0 kN, which is 28% and 56% higher than those of the conventional circular tube and square tube. The theoretical MCF is consistent with the simulated MCF, with a maximum discrepancy of 6.0%. The gradient distribution (k) of wall thickness significantly affects the crushing behaviors of the HPBT. Considering the energy absorption efficiency, the crushing stability, and the wall thickness gradient distribution, the HPBT_C2 with k = 0.6 has the best overall performance. The results can provide insights and guidelines for designing energy absorption devices with superior crashworthiness for support equipment.

The discontinuous contact and collision impact of traction components caused by attitude disturbances is a significant factor that endangers the traction reliability of the shearer. Especially, when cutting with a single drum, the shearer undergoes severe swaying and runout. Therefore, to explore the swaying law and its impact, a shearer traction dynamics model considering spatial attitude disturbance is established and validated by the traction experiment. The shearer’s spatial sway is studied, and the impact contact and its differences between the two hauling departments under different loads are discussed based on attitude analysis. The results show that attitude disturbance increases with increased speed. Roll disturbance is the major factor that causes the vibration enhancement of the support slippers, and the vibration enhancement of the walking wheels is the result of both the pitch and roll attitude disturbances. When the left drum load is lost, the roll attitude disturbance enhances while the vibration of the right hauling department increases. When the right drum load is lost, the yaw swaying is reinforced while the vertical direction vibration on the two support slippers and the axial direction vibration on the left guide slipper increase significantly. The result provides a reference for studying the shearer’s attitude law and reducing traction impact.