Purpose is to evaluate experimentally and theoretically a mechanism of solid media fracturing by means of explosive charges varying in their cross-sectional shapes. Methods. The Mohr-Coulomb strength condition has been applied to describe rock transition to the disturbed state. The condition has become a basis to develop a mathematical model of explosion (i.e. shock and detonation wave) of the concentrated borehole charges. The simulation explosion was modelled while adequate load applying at the points belonging to the outline of both cylindrical charge and at the charging angles in the shapes of triangular and square prisms. The evaluation mechanism of solid media fracturing by means of explosive charges, varying in their shapes, used the models made of optically active materials. A method of high-speed photorecording of the process was involved; the method was combined with the photoelastic technique of stress analysis. Findings. Taking into consideration rock transition to the disturbed state, the Mohr-Coulomb strength condition was applied with the possibility to simulate failures resulting from shear as well as from separation according to the developed mathematical model. The calculation results have helped identify distribution of a geomechanical parameter (Q) at different time points (time iterations). Dependencies of changes in the maximum component of the main stress tensor σ1 / γН along the axis passing through the charge centres perpendicularly to its flat surface for different time iterations have been developed. It has been defined that the maximal stresses are concentrated on the top of both triangular and square prisms helping shape a denser crack network within the zones. Originality. It has been identified that at the initial explosion stage, the maximum values of the main stress tensor component σ1 / γН along the axis passing through the charge centre perpendicularly to its flat surface, experience certain change depending upon a power law with the increasing distance to the charge outline. At the same time, if the charge is of a square prism shape then time iteration being i = 5 makes the main stress decrease according to a linear dependence. Practical implications. The research may be used as the basis for the development of rational parameters of the resource-saving methods applied to separate hard complex rocks in terms of open pits where building materials are mined.
Purpose. The aim of the work is to substantiate the technological parameters of effective use of reinforced soil-cement piles obtained by jet mixing technology. Such studies are needed to determine the possibility of increasing the bearing capacity of pile foundations in the body of earthen structures of buildings and roads. Methodology. Determination of bearing capacity of reinforced soil-cement piles was carried out by reasonable choice of structure, soil base, material, depth of piles in accordance with engineering and geological conditions, structural scheme of the structure and method of their arrangement. Findings. Significant differences in soil engineering and geological elements in plan and depth necessitated an in-depth study of soil characteristics, so it was decided to determine their strength and deformability based on static probing of reinforced piles. Analysis of the results of static studies showed that the soil-cement pile, reinforced with a reinforcing frame, has a higher bearing capacity in soil and material, and the unloading branch confirms the fact that in specific conditions the soil and piles work in elastic mode. Originality. It consists of the obtained dependences of the change of vertical loads on the reinforced soil-cement pile, created on the basis of brown mixing technology. Graphs of the dependence of the values of deformations occurring during the action on the reinforced soil-cement pile under static loading and unloading are obtained. Practical value. In practical conditions, the solution for the manufacture and testing of static load of the experimental reinforced soil-cement pile was implemented at the construction site. The manufacturing technology is designed so that the spatial frames of the soil-cement element with a length of 5…7 meters are immersed under their own weight, and the frames of 12 and more meters are lowered with a vibrator.
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