This paper is devoted to the problem of determining critical loads for stability loss of mine working contours under conditions of elastoplastic strain. Stability loss results in such processes as soil heave, distortion of the roof profile, expulsion of the developed material into the mined-out space. The mathematical model of stability loss is based on the Leibenzon-Ishlinsky method, which considers this process as adjacent to the basic process of rock mass deformation. Also the Shenly hypothesis is applied, suggesting continuous loading at the moment of contour stability loss. The problem is solved within the framework of plastic flow theory and the theory of plasticity.

During the operation of certain structures, two questions arise: about the stress-strain state (SSS) at a point and in its neighborhood on the surface of the object under study and in its bulk, and about the remaining material strength in the considered area. The values of stresses and strains not at a point, but in a neighborhood, make it possible to use the results of the proposed research to test existing numerical and analytical calculation schemes, to find the direction of growth or decrease of the quantities under consideration, and to predict catastrophic events. It is proposed to assess the state of the material using classical formulations and methods of solid mechanics, which guarantee the existence and uniqueness of the solution and continuous dependence on the input data. To determine the SSS of the material in the neighborhood of the point, we start with the full unload of the latter in order to determine the unloading displacements at the boundary. The SSS within the area, including stresses at the boundary, is found from the known boundary displacements. When studying the SSS inside the body, it is proposed to install elongated reference elements with their ends reaching the surface. To measure unloading displacements, the existing optical, mechanical, and tensometric systems are used. The uniqueness of the proposed approach is in considering not only radial displacements, but also tangential ones. The aim of the work is experimental and analytical determination of the SSS at any point of the structure and at any time of its non-stop operation.

Аннотация Массив горных пород при деформировании проявляет блочную структуру строения, возникающую в связи с дилатансией пористость.Предполагается, что учет этих факторов возможен с помощью периодических функций координат.В той точке пространства, где расположен блок, жесткость среды выше.В точке пространства, где находится промежуток (слой) или пора, жесткость минимальна.С применением тригонометрических функций решена задача об одноосном сжатии пластины, у которой структурные элементы расположены в соответствии с направлениями действия максимального касательного напряжения.Предполагается, что проявление блочности связано с модулем сдвига.В таком же виде конечно-разностным способом решена задача о напряженно -деформированном состоянии массива пород с цилиндрической выработкой с блочной структурой, повторяющей ее контур (зональная дезинтеграция

This paper describes experiments conducted to test the assumption that the source of the agent that causes nuclear transmutations in LENR can be metals heated to a sufficiently high temperature. Tungsten filaments in incandescent lamps, hot iron rods and tungsten powder were used as the heated metal. Heat releases much greater than the electricity used to heat the material, and the formation of many initially absent chemical elements was found. Based on the experimental results obtained by the authors and other researchers, a generalization of the properties of LENR is made, which can form the basis of a theory of this phenomenon. (c) 2022 ICCF. All rights reserved.

In order to estimate the structure of an object it is proposed to perform a short-term loading on its surface, followed by registration of time-varying displacements on it.

It is proposed to evaluate the effectiveness of the tool penetrating by the medium resistance to this action - the lower the resistance, the more effective the tool. The medium resistance can be determined by using rigid-type loading devices, when the immersion rate of the tool is monitored at steady loading speed. Another method is shock loading with measuring the penetration depth and the time to reach the depth. The paper provides a solution to the problem in dynamic setting that is the medium resistance to deformation is set at a given tool mass, its initial speed of immersion, known values of penetration depth and time. Comparing the resistance of the medium for differently sharpened tools, the one that delivers the minimum resistance of the medium at penetration to a given depth is selected.

In the framework of the Leibenzon-Ishlinsky approach, the problem of the loss of stability of a pillar of a cylindrical mine working is solved. The pillar material was assumed with an initial anisotropy corresponding to the layered structure. A criterion for loss of stability is being constructed, a solution to the system of differential equations of the problem in the form of combinations of cylindrical and trigonometric functions is determined. From the fact that the determinant of a system of homogeneous algebraic equations is equal to zero, the critical load value is found at which, along with the main continuation of the deformation of the pillar, something else is possible with a changed surface geometry. The influence of the initial anisotropy, the parameters of the pillar (height, radius) on the values of the ultimate load is investigated.

For media with periodic changes in Young's modulus and yield strength, the problems of stress, strain and displacement distribution around single excavation of spherical and cylindrical shape are solved. The density of the medium is determined by the difference between the elastic modules and the yield strength in the blocks and interblock space. In each case analytical solutions are obtained. Influence of blocks quantity on length unit and differences in properties of blocks and interlayers on the nature of changes in stress, strains and displacements was studied. It is noted that blockness is one of the factors that form zonal disintegration around excavations.

The problem of defining the stress-strain state of a rock mass near the working contour is solved by the Cauchy stress vector and the displacement vector set on it. To do this, you also need to know the elastic properties and the passport curve of the material “tangent stress – shift” with a section of extreme deformation. The information obtained in solving the problem allows us to judge the condition and remaining reserve of strength of the material both on the contour of the rock mass itself and in its vicinity.

In the paper stress-strain behavior of solid during flat strain in case of its volumetric incompressible behavior and ideally brittle destruction is studied. Parameters of the system of differential equations of balance and its correlations are obtained. In this case, condition of stress and strain tensors axiality is used. Boundary problem for determination of stress-strain behavior at destruction zone is formulated. As example, equations of ideally brittle out-of-limit deformation of solid in form of rectangular plate (pillar) during uniform compression are considered. It is shown that when displacement of side border of the plate is observed, it is possible to predict its destructions.

Россия 2 Новосибирский государственный университет экономики и управления, ул.Каменская 52, г.Новосибирск 630099, Россия Для сред с периодическим изменением модуля Юнга и предела текучести решаются задачи о распределении напряжений, деформаций и смещений вокруг одиночных выработок сферической и цилиндрической форм.Блочность среды задается различием в модулях упругости и

In case of unstable cone-shaped pitwalls and dumps, the overlying rock weight is of importance. Different weight of overlying rocks generates different vertical pressures per horizontal sections of pits and dumps. In case that the type of a failure surface is known for the present slop of pitwall or dump, it is possible to detect a critical section of the maximum pressure. The location of the critical section is governed by the height and the bottom radius of a pit or a dump. This study relates the destruction zone location with the height and bottom radius of open pits (dumps). The results of the theoretical and experimental studies are reported.

It is proposed to assess the stress-strain state of a rock mass and its defects by measuring displacements of mine working contour. Algorithms and software to solve the elastic and elastic-plastic problems are worked out for a case when a working contour shifts to failure domain To compute of the working contour displacements, when all the shears except creep-strain occurred, the researchers set forth the process for continuous stress release in the contour of the preset geometry at continuous monitoring and recording of shear benchmark data at its boundary The process is demonstrated on shear measurements on a circular hole in a rubber plate under tension load.

The authors determine stress and deformation in a heterogeneous rock mass at the preset displacement and Cauchy stress vector at the boundary of an underground excavation. The influence of coordinates on Young’s modulus, shear modulus and ultimate strength is shown. It is found that regions of tension and compression alternate at the excavation boundary—i.e. zonal rock disintegration phenomenon is observed.

Some overdetermined problems, formulated for the Laplace equation in a circle (for arbitrary class of functions, not necessarily analytical) and a half-plane, the heat equation, the one-dimensional wave equation, the elasticity equations for planar deformation, the plasticity and deformations theory problem for a plane with a circular hole, dynamic elasticity theory problems for a half-plane and a half-space with simultaneously known on one its boundary the Dirichlet condition, and the Neumann condition are investigated. Analytical and numerical solutions are constructed, stress-strain states, thermal and other states are restored, internal structure of the body, concentrated sources are determined.