The problem of DEM contact models choice is described in the article. An analysis of the input data calibration, including a choosing the contact model, is performed. The main theoretical positions of the most popular models are considered, their comparison is made on the basis of a specially designed stand. Description and justification of the designed stand are considered. The analysis of the obtained results is carried out. Recommendations on the choice of the DEM contact model are given. The results show that it is time-efficient to use non-linear contact model for future model calibration.

The authors conducted the analysis of the peculiarities on the destruction of rock formations by means of tunneling and mountain combine tools. They specify key criteria for choosing the rational parameters of cutting executive bodies in mountain combines. The article lists the factors influencing the efficiency of mine rock cutting. It is noted that the key drawback of mountain massif destruction with cutting is that consecutive elementary rock chips separation occurs under the influence of compression loads. The least energy-intensive way of destruction of rocks is a method that involves the destruction of mountain massifs chiefly under the influence of tensile loads, that is, by detachment. A design is proposed which is a combined executive body of the tunneling and cleaning unit including a bar executive and two-sided hydrocylinders-tractors installed inside the bar beam. The operation principle and procedure of the proposed executive body are described. The use of the proposed executive body will allow one to destroy the mountain massif in the most energy-efficient way ensuring high productivity and the lowest specific consumption of cutters.

The designs of submersible hammers and dampers protected by patents for reducing the vibration of the drilling rig of roller drill machines are proposed. The variants of modernizing drilling rigs for drilling hard rocks and faces of complex structures are considered. Particular attention is paid to the joint work of submersible shockers and pneumatic shock absorbers, the preferred schemes for the arrangement of these devices by drilling rigs are indicated. The results of experimental tests of machines with pneumatic hammers are presented to determine the vibration performance and drilling speeds. The pneumatic hammer allows increasing the speed of drilling process to the intensification of the destruction of the plain face by the shock load and the cleavage of the protrusions of the unevenness of the face, the better fitting of the bit to the face and the release of the blades or the bit pins from the drill bit. The choice of a particular type of damper or shock absorber depends on its design scheme and the possibility of changing the design of the drill string. With the complexity of installing a damping device in the mast (with significant dimensions of shock absorbers and drilling of strong heterogeneous rocks), it is advisable to use a set of tools to reduce hydraulic pulsations in the mains and cylinders of the hydraulic system by installing chokes in the oil plants and pneumatic shock absorbers. It is proposed to use the device for the development of pneumatic hammers by a patent-pending drilling method with a hollow piston filled with magnetically active heavy liquid, which will allow controlling the frequency and size of the shock pulses and partially compensating for the drill string fluctuations arising from the uneven immersion of the bit in the array. It is noted that the proposed solutions increase the drilling speed by an average of 15%.