Herein there is a description of algorithm of the automated forecast of stability for soil slope structures including input of initial data regarding physical and mechanical properties and geometrical parameters of a structure, building of the most intense sliding face, computation of the slope stability by the polygon of forces method. Developed on algorithm basis, The Stable Slope software package has been implemented in open pit located in the Altai region. There are calculation results of the parameters of the Eastern steady side (slope angle at a given height) depending on the inclination angle of contact of the friable Quaternary deposit with a parent rock. Recommendations can improve work safety under adverse natural and man-made conditions causing formation of unstable water-saturated zones.

Introduction. During opencast mining, the development of mine workings in clays of Quaternary deposits is often accompanied by stability loss. As a rule, the reason for the development of geomechanical processes 46 "Izvestiya vysshikh uchebnykh zavedenii. Gornyi zhurnal". No. 3. 2021 ISSN 0536-1028 is the mismatch between the accepted geometry and physical-mechanical characteristics of soils. In case strength characteristics and moisture content are strongly related in the conditions of lacking water saturation sources, slopes remain stable for a long time. However, in the case of water saturation, soils change to plastic or liquid consistency, and the strength properties are reduced. In engineering practice, to prevent hazardous geomechanical processes, electrophysical methods are applied that make it possible to build the boundaries of soil moisture anomalies through electrical contrast. In the instances when the water-saturated strata occurrence depth and thickness is known from drilling and vertical electrical sounding data, electrical profiling makes it possible to promptly determine the variability of these characteristics of the anomaly. The authors proposed an algorithm of water-saturated strata thickness variability determination from the point of electrical profiling. Research aim is to predict the stability of the marginal rock mass in clays of Quaternary deposits, taking into account the effect of filtration reservoirs by combining engineering-geological databases and geophysical measurement results based on the 3D geological-geophysical model. Methodology includes the analysis of the engineering-geological databases and geophysical measurement results. Results. A 3D geological-geophysical model of the marginal rock mass with the boundaries of the watersaturated stratum was built from the results of the research to predict the stability of the marginal rock mass’s actual position. Slope stability analysis established the following: at design sections О3у3–О5у5 after deformation, retaining forces exceed shearing forces significantly (safety factor) because the weight of the base wedge grows due to landslide masses; potential landslide hazard area is associated with the design section О1у1, which is due to smooth fall of the stability factor from 1.38 (section О2у2) to 1.06, close to ultimate. Conclusions. For the extension of the marginal rock physical-mechanical properties variation it is appropriate to apply the method of electrical prospecting (sounding and profiling) determining watersaturated areas by local negative anomalies of effective electrical resistivity and establishing the function of loose Quaternary deposits thickness variation by the inversion of electrical profiling graphs with the use of the least square procedure and the golden section method. If landslide hazard areas are vast, the variation of the stability factor design values, which were determined based on 3D geological-geophysical models, may possess the non-monotonic character with several extreme values and significant gradients. For that reason, it is appropriate to carry out computerized analysis with a cyclic extension of the most hazardous areas by the coordinate of the profile and the direction of the design section in a plan.

Introduction. The reliability of geomechanical prediction depends on the level of detail of databases covering geological structure, geometry and physical properties of the rock mass under investigation. In order to improve the accuracy of coal pit wall stability prediction, following the generalization of databases containing geological survey, groundwater monitoring, geophysical sounding and mine surveying, it is advisable to construct three-dimensional geological-geophysical models accounting for the main adverse factors, and thereafter search for the most hazardous section. Research aim is to predict wall stability according to the developed algorithm based on the threedimensional geological-geophysical model. Research methodology includes a search for the most hazardous rock mass site section by the ratio between shear and retaining forces within the established zones with anomalous physical characteristics. Results. By generalizing databases containing geological studies, groundwater monitoring, geophysical sounding by the method of electrical resistivity tomography, and mine surveying, a three-dimensional geological- geophysical model has been constructed of a wall loaded with “heap of dry rock atop of the hydraulic dump” man-made structure and undermined by underground works. The trial site stability has been predicted for the true state of mining. Comparative analysis of the obtained data has been carried out. Summary. The combination of natural and man-made factors, including hydrogeological conditions of the territory, seasonal and climatic behavior, tectonic faulting of the deposit and shear zones connected with undermining result in the development of a rather complex geological structure of the wall which includes local deconsolidated and waterlogged zones significantly reducing the stability of the pit slope. At the trial site of Kedrovsky pit due to spatial and temporal alternation of properties and state of rock within the landslide hazardous zone, the variation range of the factor of safety in six typical sections amounts n = 1.06–2.39. For that reason the objective prediction of slope stability in similar conditions (in addition to geological survey and hydrogeological observations data analysis) should include geophysical monitoring of anomalous zones origination and development, hereupon creation of a treedimensional geological-physical model, and the automated calculation of the factor of safety including repeated selection of the most hazardous section.

Introduction. Slope stability analysis reliability depends on the level of schematizing the results of engineering-geological survey, hydrogeological monitoring, electrical sounding, and mine surveying data generalization. In order to improve the stability analysis accuracy, it is relevant to use the geomechanical models, which take into account the spatial variability of the adjacent rock mass physical and mechanical properties, with further search for the most hazardous section in the plan. Research aim is to substantiate the relevance of slopes physical and mechanical monitoring by the methods of downhole control and further stability analysis with the use of the geological and geophysical models. Methodology includes the search for the most hazardous section of the rock mass by the ratio of the shearing and restraining forces within the limits of the established zones characterized by the variability of physical and mechanical properties. Results. As a result of generalizing the databases of the engineering and geological study, hydrogeological monitoring, electrical sounding and mine surveying, the volumetric geological and geophysical models were built of the technogenic massif formed at the dump, as well as the slopes of the hydraulic overburden face, represented by the three-level fill of dry overburden. Test areas stability has been analyzed for the actual position, and the comparative analysis of the results was made. Conclusions. When building volumetric geological and geophysical models of man-made rock masses formed at the areas of filled hydraulic waste diposals, in addition to the results of the traditional survey measurements and direct engineering and geological study, it is important to create informative databases on spatial and temporal variations of physical and mechanical properties of alluvial rock conditioned by their fluid loss and consolidation, which with in details at cross hole intervals may be obtained based on the statistical dependences on electrical conductive properties variation by the methods of electrical sounding or tomography; and when making enclosing embankments (bridges) of dry rocks – information about excess pore pressure under these facilities. When using the hydromechanized method for the alluvial rocks, relatively homogeneous in strength properties, the hydraulic overburden face slope stability is determined to the greatest extent by the absolute values of the accumulated strength indicators in the mined area and the unfavorable combination of the edge shape (the presence of protruding sections and face unevenness in the plan) with the entry height. The established range of the stability coefficient was n = 1.03–3.76. The stability of the enclosing structures made of dry rock to the greatest extent depends on weak alluvial layer depth and thickness and the absolute value of excess pore pressure in this layer. The established range of stability coefficient variation for this rock mass section is much narrower and amounted to n = 1.29–1.59.

Introduction. Sloping structures (quarry sides, dumps, banks, cuts, dams, etc) stability forecasting accuracy improvement requires detailed elaboration of physical-mechanical properties of the rock mass under consideration. Traditional methods of well engineering-geological exploration and hydrogeological monitoring are therefore supplemented by geophysical study. Research aim is to diagnose unstable deconsolidated and wetted zones in marginal masses for the purpose of further forecast of quarry sides stability. Methodology. Databases of geophysical studies obtained by the expeditions of the services of the Republic of Uzbekistan at Angren open pit. Results. For the test area represented by 11 seismic stations at the southern side of the quarry, the criterion assessing the state of the site as potentially landslide hazardous according to the results of circular seismic sounding has been experimentally obtained. With the use of this criterion, in the plan of the landslide zone the borders have been established. For the test area represented by 16 geophysical profiles at the northers side, by electrical profiling graphs and geological sections for the corresponding profiles, 58 "Izvestiya vysshikh uchebnykh zavedenii. Gornyi zhurnal". No. 1. 2020 ISSN 0536-1028 the following regularities have been found: at profile areas adjacent to the runs (rivers), local negative anomalies of effective resistivity up to 20–50 Ohm ∙ m are observed connected with soils wetting; between the anomalous areas the alternation of effective resistivity qualitatively coincides with the alternation of the thickness of a layer of loose deposits. By the arrangement of the negative anomalies borders at the graphs pf effective resistivity dependence on the spread of the profile along all profiles (PR1–PR16), the borders of the wetted zones were established in the plan of the test area. Summary. For geomechanical processes monitoring in the landslide zones it is advisable to apply the method of circular seismic sounding determining the value and the anisotropy coefficient according to the extreme values of compressional arrival time. For the conditions of the Angren open pit, the criterion of potential hazard of landslide development is the value of the anisotropy coefficient higher than 1.6. When elaborating the detailes of the physical properties of landslide zones in quarry sides which are weakened by sand-clay Quaternary sediments, by the method of electrical profiling it is advisable to use: the linear dependence on the thickness of Quaternary sediments on the value of the effective resistivity; hyperbolic dependence of soils relative wetness within the water saturation zones on the value of the effective resistivity ascribed to the reference value defined in the site of soil samples collection, and the borders of wetting zones are to be established by the negative anomalies at electrical profiling graphs. In order to construct the solid geologicalgeophysical models of the landslide zones of the sides, in addition to the geological sections data, the following results of geophysical sounding should be used: the boundaries of landslide zones in the plan, detailed contact geometry of loose Quaternary sediments with bedrock; soil properties modified by wetting