In the process of rock bolt support for the roadway with floor heave, the rock bolt cannot reach the bottom of the borehole smoothly due to the influence of the collapse gravels around the borehole. In order to solve the problem of difficult rock bolt installation, the auxiliary installation device of rock bolt drilling was innovatively designed. At the same time, a new method of auxiliary bolt installation was put forward, in which a bit was installed at the bottom of the bolt to assist the bolt drilling. The drilling process of the bit was simulated by the co-simulation of discrete element method (DEM) and multibody dynamics method (MBD). The axial resistance of the bit and the change law of the particles movement were studied under different motion parameters and structural parameters. It was found that the drilling performance of bit was directly related to the motion parameters and structure of bit. And the selection of gravel parameters in DEM was verified by experiments. The research results can provide technical guidance for bit structure design and the selection of motion parameters of bolt drilling auxiliary installation device, and can effectively improve the rock bolt installation efficiency.

Thin-coal-seam shearer mining efficiency is seriously restricted by the poor loading performance of the drum. The loading of the drum to the cracked coal lumps is based on a screw-conveying mechanism, and its loading performance is influenced by many structural parameters, including drum width, helical angle, axial tilt angle, number of blades and form and diameter of the barrel. The barrel diameter directly influences the drum envelope zone’s capacity, and its influence on loading performance is not yet clear. Therefore, this work first compared the drum-loading results between experiments and numerical modeling, and the results proved that the application of the discrete element method (DEM) to the modeling drum loading process is feasible and the results are reliable. Secondly, the influence of barrel diameter on particles’ axial velocity, loading rate and web depth was studied using the ejection and pushing modes. The results showed that the particles’ axial velocity has a noticeable impact on loading rate under ejection loading conditions, and the loading rate first increases and then decreases with the increase in barrel diameter. When the diameter is less than 700 mm in drum-pushing modes, the particles’ axial velocity plays an important role on drum loading; the filling level has an obvious impact on loading performance when the barrel diameter is larger than 700 mm. The drum loading ejection rate is 25% higher than that of pushing mode, which is due to the loading rate of particles located in a web depth from 300 to 600 mm. The influence of barrel diameter on loading performance using drum ejection is more obvious than that in pushing mode. The results provide a reference for drum structural design to some extent.

No abstract