Botakoz Imansakipova

The article investigates the problems of mine hazard prevention, identification and control. Acoustic emission signals are one of the important signs of the appearance of deformations in rocks that can cause accidents in mines. Acoustic emission signals are quite broadband in nature. The article considers the task of the possibility of using broadband nature of acoustic emission signals to localize areas in which acoustic signals are generated for early warning of an emerging danger. The results of modeling of the process of localization of hazardous areas are presented. The proposed method is based on the frequency dependence of acoustic signal attenuation in rocks. Moving away from the signal source, not only changes its intensity, but also its spectrum. By measuring the intensity of acoustic signals in several spectral bands and knowing the frequency dependence of signal attenuation, it is possible to calculate at what distance from the receiving points the signal source should be located so that its spectral components would be changed as they are observed at the receiving points. This allows to localize the signal source. It is shown that four signal reception points and intensity measurements in two spectral frequency bands are sufficient to apply the method. It is shown that the proposed method allows not only to determine the coordinates of the local area of fracture formation, but also to restore the spectral characteristics of acoustic emission signals in the area of their occurrence, which can provide information about the mechanism of formation and development of processes of rock destruction.

Purpose. Reducing the dispersion of radar reflections from local objects, with multi-frequency sensing, to solve the problem of orientation by radar reflections from objects. Methodology. Reflections from local objects in the entire frequency range of the radar station (RS) at the same radio engineering position were measured by three independent radars of the same type on different days and at different antenna elevations. The deviation of the radar stations in the position did not exceed 500 meters. Coordinates (azimuth, range) of reflections of several separate local objects were allocated for each radar. The average values of reflections from local objects and their dispersion in the frequency range were calculated. Using various algorithms, individual frequencies were sampled and the reflected signals were averaged at these frequencies. The decrease in the dispersion of the reflected signal from the number of frequencies at which reflections were measured and from the algorithm for selecting these frequencies was investigated. Findings. Averaging the values of reflections from local objects for several frequencies leads to a decrease in dispersion and, as a result, to a more accurate correspondence of the reflected signal level to the geometric size of the local object. The variance decreases most rapidly for a small number of frequencies selected for averaging when selecting frequencies located in an interval of at least 1% relative to each other. Originality. To solve the problem of orientation based on radar reflections from local objects, it is necessary to identify the landmarks selected on a digital terrain model. Due to the fact that local objects (hills) are a collection of many reflectors falling into the allowed volume of the radar, with different levels of reflections and random phases, there may not be radar reflection from a local object at a certain frequency, or it may be very small. In order to unambiguously identify all landmarks, measurements must be carried out at several frequencies. The work has established how many frequencies measurements should be performed at and on what principle these frequencies should be selected. Practical value. The advent of digital terrain models made it possible to solve the problem of terrain orientation by comparing radar reflections from local objects with reflection models based on digital terrain maps. Radar reflection models use mathematical expectations of reflection values, unlike real reflections, which have random deviations in signal levels depending on the operating frequency. Reducing the variance of these deviations increases the accuracy of identifying characteristic local objects (landmarks) used to orient the radar in the absence of data from satellite navigation systems.

Purpose. Development of a new approach to improving the accuracy of orientation based on radar reflections from local objects and a digital terrain model. Methodology. The research is based on the theory of radiation, reflection and reception of radar signals. Statistical analysis of a large volume of recorded signals establishes causal relationships between the appearance of “false” reflections formed by the back lobe of the radiation pattern and to develop a computational algorithm for their suppression. Findings. A method and software that allows detecting and suppressing “false” reflections formed by the rear lobe of the antenna pattern without distorting the reflections created by the main lobe. For this purpose, a criterion has been developed, determined by the ratio of the amplitude of the signal received by the front lobe to the amplitude of the signal recorded by the rear lobe. The criterion allows eliminating the “false” signals without having a priori information about the real radiation pattern using a regulator for the reduction of phantom reflections to an average noise level. Originality. For the first time, suppression has been carried out of “false” reflections without having a priori information about the real radiation pattern of the radar station antenna, as well as elimination of the loss of informativeness of the real reflection formed by the main lobe. Practical value. A method is suggested of radar immunity of radar stations is noise immunity due to “false” reflections. The potential of the method and the capabilities of the developed computer program determines the relevance of their capabilities for use by all radar stations at various frequencies, azimuths, ranges and terrain features.

Purpose. Establishment of regularities of variability of pressure dynamics in the reservoir and development on this basis of methods of control and regulation of hydrocarbon production. Methodology. To achieve this goal, experimental studies were conducted, and the results of the experiments were summarized. Findings. Pressure distribution functions for stationary fluid inflow in two planes have been established, which allow monitoring and management of mining operations, especially at late stages of development. Originality. Based on the established regularities, a model of pressure distribution in the reservoir in a two-dimensional plane has been created. An experimental study of the pressure distribution in the reservoir was carried out, which allowed us to remove the characteristics of the pressure distribution along the axis of the segment of the oil reservoir under varying boundary conditions. Practical value. A mathematical model of pressure distribution processes along the angle of inclination is proposed, which allows determining the effectiveness of flooding. The influence of the deformability of the formation, the location of the well relative to its impenetrable roof and sole, the length of the horizontal trunk and the power of the opened formation on the magnitude and intensity of the inflow to the horizontal well is estimated.

Purpose. Justification of possibility to create the hardening mixtures with filler based on tailings of the Akshatau mining and processing complex for strengthening the quarry benches, inter-chamber pillars and excavation roofs and producing building materials. Methodology. The complex approach is applied including experimental methods of physical and chemical and mechanical analysis of the phase composition and properties of ore processing wastes. The practicability of using the tailings of polymetallic ore processing as an inert filling of hardening mixtures is estimated; the compressive and bending strength of samples is determined after the mixture solidification as well. Findings. Based on X-ray phase analyses, differential thermal and chemical analyses, the ore tailings composition was determined. The optimal qualitative composition of the hardening mixture with specified rheological and strength properties, as well as the technological mode of its preparation, have been determined. Originality. The peculiarities of hydration processes in the cement-water-limestone system are clarified and a new formulation of a hardening mixture with specified rheological and strength properties have been developed. Practical value. The proposed composition of hardening mixtures with filler based on ore processing waste is aimed at strengthening the fractured area of the rock mass. This increases the stability of rock openings and provides safety of mining. The involvement of ore processing waste in the production of hardening mixtures and other building materials is a positive solution in terms of the disposal of these wastes. Reducing the amount of accumulated waste contributes to minimizing environmental risks in mining regions. The obtained results are significant for the construction industry. They provide the expansion and reproduction of the raw material base through using the waste of processing the ore of Akzhal deposit.

Purpose. Development of a new approach to improving the accuracy of predicting situations in which the earth’s surface failures occur as a result of undermining a rock mass during the development of mineral deposits. Methods. The critical situations, including the earth’s surface failures, are predicted on the basis of assessing the value of geoenergy and studying its change as large volumes of rock mass are involved in mining. Analytical solutions based on the fundamental laws of physics and mechanics of continuous media are used. The research is performed using methods of cause-and-effect analysis. Findings. Based on the cause-effect relationship, determined between the change in the value of the mass geoenergy and deformation processes on the daylight surface of the field, an effective method has been developed for ranking it according to the degree of hazard of failure formation with the simultaneous use of two criteria. One of the criteria is determined by the relative change in geoenergy during the system transition from the initial (stable) state to the current one, which becomes unstable under certain conditions. The second criterion is formed on the basis of the change in geoenergy during the transition from the current (possibly unstable) state to the final (stable) state. Originality. For the first time, when zoning the daylight surface of a field according to the degree of hazard of failure formation, two ranking criteria are used simultaneously, based on the assessment of geoenergy accumulated in a heterogeneous mass, when it is undermined in the conditions of triaxial compression. Practical implications. The territory ranking method, developed on the basis of the used criteria for hazard of failure formation, allows improving the quality of situational control, predicting risk situations and their development, as well as optimizing the short-term and long-term plans for the development of mining operations.

Development of an effective method for zoning the earth’s surface in heterogeneity of the rock mass

The combined method for assessing risk factors in underground construction

The paper deals with the task of identifying weakened ground areas above mineral deposits such that these areas are at the early stage of displacement and are yet not determined by instrumental observations. For this purpose, the zoning method has been chosen based on the criterion ratio of the total mining depth to total thickness of rock strata. The method has been successfully used for several years at the Zhezkazgan deposit to assess the geotechnical situation and its development. At the same time, there is a decrease in the accuracy of determining the boundaries of rock mass zones with higher nonuniformity in terms of density. The disadvantage is eliminated by replacing the mining depth by the reduced thickness of overlying rock layers in the above criterion. Problematic areas which are not involved in displacement process are detected by zoning in addition to areas identified by traditional methods on a situational map. Combining the results obtained by various methods can significantly improve the reliability and accuracy of prediction of critical situations. Acquisition, storage and processing of data is carried out in the advanced geo-information model of geomechanical risks (GMRT), which is the basis of a specialized GIS. The model is focused on risk assessment and preventive decisionmaking in the course of underground mineral mining. The developed method of zoning improves reliability and accuracy of hazard prediction and prevention recommendation subject to minimized loss of in-place reserves.The authors appreciate participation of PhD B. B. Imansakipova, Head of Chair, Satpaev Kazakh National Research Technical University, in this study.