The thesis deals with solving the urgent scientific and applied problem of providing more efficient and controlled forming the horizontal wells for trenchless laying of distributing underground utilities by summarizing the scientific foundations for creating some installations and equipment, substantiating their rational design parameters and creating a sample set of power installations, expanding the scope of use and engineering capabilities of static methods of forming utility cavities in the soil.
The relevance of the topic is substantiated in the work, the object, the subject, the aim and the objectives of the study are formulated, the research methods are described, as well as connection of the work with scientific programs, plans, themes is determined; information on the dissertation result testing and publishing is provided.
The scientific novelty of the obtained results is to develop the generalized theoretical dependences, first obtained on the basis of the law of equality of soil masses before and after soil destruction and the standard physical and mechanical properties of soils, contributing to the creation of special highly efficient installations for trenchless laying of underground engineering utilities based on established patterns of interaction between their actuators with the soil ground by methods of soil static puncturing, pressing and their combinations.
The thesis results involve substantiating the selection of highly efficient methods for static forming the wells for trenchless laying of engineering utilities depending on their parameters and soil grounds and in creating the algorithm for determining the rational parameters of actuators for soil excavation in each case. Technical requirements, based on the developed recommendations and the obtained engineering calculations, to create a sample set of installations have been done.
The analysis of existing approaches to improving the efficiency of trenchless laying of underground utilities has shown that the main constraining factors for extending the use of highly efficient installations of static action for creating horizontal wells in the soil when laying underground utilities are slow pace of excavation, significant energy intensity of the processes, especially close to the surface, or to the adjacent utilities and low accuracy of boring the soil-puncturing head in the soil.
Developing the methodological foundations for creating utility cavities in the soil, the analytical pattern of soil excavation with various tips has been determined for each case. That was done on the basis of the law of changes in soil density when compacted, determined by the compression module of soil deformation dependant on the physical and mechanical properties of soils. There was the possibility of obtaining the patterns of distributing the usual soil pressure on the working surfaces of actuating tools based on the law of soil mass conservation before and after compaction (without experimental studies).
Obtained mathematical dependences allowed to substantiate the possibility of reducing the resistance forces to soil puncturing up to 26% by means of using a protruding conical edge above the cylindrical part of the puncturing head, that equals to 1.08 of the diameter of the cylindrical part (in fact, the well) in sandy loam, 1.22 in clay, and 1.31 in loam and establish the optimal dimensions for effective soil puncturing with a cone-cylindrical tip, that are equal to: 236 mm for loam, 295 mm for clay and 444 mm for sandy loam corresponding to two optimal diameters. If the diameter of the well is bigger than the maximum limit, then the laying of underground utilities must be done not by puncturing, but by other methods, for example, by pressing or combined methods.
By comparing the calculations of soil resistance to tubular tip punching it has been found out that a tip with an external conical sharpening of the cutting edge is 25–30 % less than a two-conical sharpening due to the creation of additional resistance from soil deformation by the inner cone.
The rules of forming soil deformation zones while boring by actuators have been established and their sizes have been determined.
The approaches to determining the parameters of the actuator in the form of a sheared cylinder and their influence on the motion trajectory of the head in the soil have been formulated, the minimum and maximum angles of its shear has been defined depending on the soil ground and the rod rigidity.
The methodology and the algorithm for selecting methods and calculating working equipment for creating utility cavities in accordance with their parameters and boring conditions in various soils have been developed. The sample set of power installations and the parameters of their actuators have been justified.
