| Summary: | The paper discusses approaches to improvement of equipment for borehole drilling with a predetermined trajectory in construction of underground utility systems and facilities. Piercing method allows implementing dry drilling of boreholes with small diameter using simple technical equipment. The methods used when preparing the research are analysis, generalization, and experimental research methods. Outcomes of the research include evidence that increase in performance of vibro-impact piercing is possible not only due to higher impact energy, but also due to optimization of interaction between the operating tool and soil. Combination of dynamic action by impact pulses and static forces applied to the drilling equipment enables to enhance performance of impact pulse action and increase the drilling speed. Accuracy of the borehole trajectory can be provided by using dynamic stabilizers or correcting the drilling direction due to asymmetrical tool shape in combination with the torque moment of a drilling equipment. The study formulates requirements to design of a drilling unit for directed pilot hole drilling by dynamic piercing method. The design of an improved pneumatic tool installed in front of the drill string and equipped with asymmetrical front head is described. Experimental research results are given on the process of a borehole drilling using the described tool.
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