The strength criteria substantiation of water-saturated soils and mine rocks, which make it possible to obtain the analytical solutions necessary for determining the stability of water-flooded soil slopes and side-hills. Methods. The methods are applied of analysis and generalization of the theoretical and numerical experimental studies results. The rocks and soils characteristics are taken into account: specific cohesion c, internal friction angle φ, compressive strength R c and tensile strength R p of the rock, as well as the bulk density. The load q was imposed to the water-saturated seam roof from the overlying mine rock or soil seams, the weight of equipment or structures located on the surface. It was accepted that the seam is saturated with water (gas) with the excess pressure Р. A point on the mine working surface (or vertical slope surface), located at a depth z is considered. It is determined at which ratio of q, P and z parameters the soil or rock seam will be destroyed. The problem solution is based on the Mohr-Coulomb strength criterion. Findings. The strengths of water-saturated rock and water-free rock are compared. The ratios have been obtained that make possible to determine the critical load on the daylight surface of water-saturated and water-free vertical slopes, side-hills, trenches and foundation pits, as well as various mine workings in soil bases and mine rocks. The analytical solution has been obtained, which makes it possible to determine a value of the critical pressure on the water-flooded vertical surfaces and soil slopes. The generalization has been made of a certain one-dimensional Mohr-Coulomb strength condition for a water-saturated base characterized by the strength characteristics с and φ for the dimensional case. Originality. It has been theoretically proved that for any pore pressure value in the water-saturated mine rock (or soil) their strength will be less than in their water-free state. New solutions have been formulated for determining the critical height of a water-saturated vertical soil slope or the wall in the vertical mine working. Practical implications. The obtained results make it possible to solve the practical engineering problems on determining the stability of water-saturated slopes and side-hills with a load-free daylight surface, therewith, taking into account the weight of the equipment, stored material and the stability of vertical walls of water-saturated seams of open-cut mine workings.

The article identifies the main parameters of the drilling-mixing technology, which is the most effective in fixing weak soil bases during the construction and restoration of transport, industrial and civil structures. The difference of the technology developed by the authors is that the strengthening process is carried out at low pressure (0.15 ... 0.25 MPa). The relevance of the research is that the proposed technology requires less cost with high rates of restoring the strength of soil foundations. To prove the high quality of the technology, laboratory studies were carried out to determine the optimal characteristics of the soil-cement element, as well as the proportions and composition of the fixing solution. The dependences of the strength of soil-cement elements in the air-dry condition with cement content from 7% to 23% with water-cement ratio in solution 1 / 0.3 and with cement content from 13% to 37.5% with water-cement ratio in solution 1/0,6. During the experimental-industrial studies of the author’s technology, the embankment was constructed with the soil-cement-reinforced elements for the access road approaches at one of the facilities in Kirovograd region, which ensured safety in the operation of a complex transport structure.

A review of the scientific and technical literature on the re-alignment of the route during the transition to high axial load from the accepted today (23.5 t/axis) to the perspective (25 t/axis) shows that in the stage of preliminary researches imitation modeling of the earth web by the finite element method (ITU) as the most convenient, accurate and illustrative of the known numerical methods. In order to provide recommendations on the strength of the subgrade when moving to a higher axial load up to 25 t/axis, an analysis was conducted, the essence of which was to compare the stress-strain state of the subgrade at two loads per axis: 23.5 t/axis (existing ) and 25 (perspective). All the geometric and deformation characteristics of the formation are taken from data on a two-track section with a height of embankment of 3. The deformation characteristics are chosen so that the working material of the formation is in accordance with the average indices of deformation capacity of the railways used. The ITU train load calculus makes it possible to obtain all the factors of VAT in it, which is the main purpose of the study of the strength of the earth cloth, and allows to forecast their development in the future.

Purpose. Perform a comparative analysis of drill and injection (jet-grouting) and drill and mixing technologies of micropiles arrangement of weak soil bases with the identification of technological features that significantly effect on the design and calculation of weak soil bases strengthening. Methodology. To solve this problem, was conducted of the detailed analysis of the most effective methods of micropiles arrangement during the strengthening of weak soil bases (physical immersion, bored and packing of concrete, drill and injection of ground, drill and mixing soils and application of special effects). Peculiarities of technological parameters of jet-grouting and drill and mixing technologies are considered in detail. The advantages and disadvantages of each of the technologies are revealed. It is proved that the drill and mixing technology has a greater degree of prediction of the stress-strain state change of the inhomogeneous base. To determine the influence of deformation characteristics, a spatial finite-element model based on a flat prototype was created, which was built using automatic triangulation of the professional calculation complex SCAD. Findings. A significant reduction of the deformed state at an almost constant stress state is obtained. When the deformation characteristic increases by 3 times (the ratio of the modulus of elasticity of the soil cement pile and the weak soil), the vertical displacements of the foundation decrease by 1.23 times. Originality. It consists in obtaining the dependence of the change of vertical displacements and stresses on the modulus of elasticity of the soil cement micropile, created on the basis of drill and mixing technology. Practical value. It consists in the obtained results of comparative analysis of substantiation of micropile installation drill and mixing technology during strengthening of weak soil bases with definition of technological features and choice of drill and mixing as the most effective variant from the point of view of technology realization.

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