The presented results of scientific research are aimed at increasing the efficiency of trenching for laying the utility lines using new less energy-consuming technologies of excavating the soil with the working equipment of multi-scraper excavators. The proposed method of determining the efficient operating modes for excavators when digging a trench is based on the idea of cutting the soil with the blades at a critical depth level, which guarantees consumption of minimum specific energy and maximum efficiency of the machine. This becomes possible if the operation of such blades is provided with the absolute values and the ratio of the speeds of cutting and submitting the working body into the face. To determine the efficient modes of multi-scraper excavators and the size of their edge side blades, the conditions of their effective unloading were identified and the patterns of changing the soil movement over the surface of unloading scrapers depending on the time of unloading were determined. For the same purpose, the dependences of the blocked cutting speed on the trench width were determined and the technical performance of the excavator was specified on the basis of determining the soil bearing capacity for one group of blades. It is found that the time of unloading the soil from the scrapers very slightly depends on their angular velocity within its change in the unloading zone. On this basis, the maximum angular speed of the scrapers is determined. The identified indicators are related to the width of the edge side blades performing asymmetric locked cutting, whose dimensions were determined by calculations. The obtained efficient operating modes of scraper trench excavators and the size of their edge side blades allow developing practical recommendations for improving the working equipment of excavators of this type

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Purpose. Building of new railway tracks and facilities, repair and replacement of existent underground utilities and communications is related to the receipt of horizontal cavities in soil by trenchless method. A static soil broaching with a working body with cone tip is the most widespread method in practice of forming a pilot hole at the trenchless laying of distributive communications. However, in the process of implementation of project calculations, receipt of pilot hole and subsequent expansion to the necessary sizes, there is a question of workings effort calculation methods. Existent methods are based on empiric dependences and experimental coefficients which diminish exactness of calculations and increase the cost of works. Methodology. The work proposes the dependence for determination of equivalent diameter of cone tip depending on the hole diameter and theoretical method for calculation of optimum parameters of soil broaching head using the well-known parameters: type of soil and its humidity, that determined by the State Construction Regulations (DBN). Findings. The results of the theoretical studies can be used to increase the efficiency of the working equipment for soil broaching by static method during trenchless laying of underground utilities and communications. Originality. The authors establish the dependence of the equivalent diameter of the cone base on the diameter of the cylindrical part of the broaching head, which allows for removal of the frictional force from the static broaching on the lateral cylindrical surface of the tip. Practical value. The obtained theoretical calculations for determining the optimal diameters of the cone tip with soil broaching spurs made it possible to establish that if thediameteroftheconeisgreaterthanthemaximumdiameterofthehole (soilcavity), thenthefrontalresistanceofthecone-cylindertipincreasesmoreintensivelythantheresistanceofthecylindricalpartofthetip. The maximum reduction in the broaching force takes place for a soil cavity whose diameter is 2 times smaller than the maximum limit diameter. When conducting the calculations regarding the choice of the size of working bodies for soil broaching, the source data include the type of soil, and its characteristics by DBN, as well as the moisture content of the soil determined by traditional methods.

Special digging machines are used currently in many countries when laying underground utility systems of various types. They are designed to form holes with a complex path. Vermeer, Straight Line, Ditch Witch (USA), Tracto Technik (Germany) are the world's leading manufacturers of such machines [1]. However, initial hole entry for these

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