The purpose of the study is to create a new design of the working tip for the perforation of the soil when laying two or more buildings trenchless way and determine its rational parameters. Method. It is known that for static perforation in the formation of cavities in the soil for communication is traditionally used cone-shaped working elements, which is the most common, cheap and reliable. However, the study revealed inefficiency. The design of the working elements of the soil perforation for trenchless laying of two or more buildings simultaneously in the form of a tip, which consists of a wedge-shaped part and a control part in the form of a rectangle with half-cylinders. The basic principles and mathematical dependences of determining the size of the working body are described. Scientific novelty. Regularities of changes in soil pressure on the lateral, conical and wedge surface, flat and cylindrical part of the tip, allowed to obtain an analytical dependence for the calculation of the resistance force depending on the physical and mechanical properties of the soil, the diameter and the number of cases established simultaneously. Also, when comparing the cone-cylindrical and flat tips, it can be argued that the breakdown force of the flat tip decreases from 1.2 to 1.7 times.

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

No abstract

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.

The presence of analytical dependencies describing the process of static soil puncture by a working body with a conical asymmetric tip is necessary to create installations with the ability to control the trajectory of the soil puncture. The paper considers the features of the process of interaction of an asymmetric conical tip with the ground. Analytical relationships were obtained to determine its reactions during a static puncture, the deviation of the head trajectory from a straight line, to determine the size of the soil compaction zone and the magnitude of the destructive force that acts on adjacent communications and other underground objects. It was found that with an increase in the value of the displacement of the top of the cone, for example, from its axis from 0.02 m to 0.08 m with a borehole diameter of 0.2 m, the value of soil resistance increases almost four times. The greatest resistance is achieved when piercing a hard sandy sand. It was found that with an increase in the displacement of the tip of the tip cone, the deviation of the trajectory increases. The piercing head achieves the greatest deviation from the straight trajectory of movement with a sharper cone and a greater asymmetric deviation of its top, and, for example, in hard sandy loam can be up to 0.17 m with a span of 10 m. It was found that the size of the soil destruction zone will be almost 1.8 times larger than the tip in the form of a symmetrical cone and reaches from 8 to 12 borehole diameters, depending on the type of soil. The maximum pressure on adjacent objects can reach from 0.06 MPa in hard-plastic clay to 0.09 MPa in hard sandy loam. The calculated dependences obtained for determining the power and technological parameters depending on the geometric dimensions of the asymmetric tip of the working body can be used to create installations with a controlled static puncture for use in the most common soil conditions.