AbstractIntroduction
TopicalityAnalysis of current trends of underground coal seams of Ukraine suggests that with increasing depth of mining operations are becoming increasingly common scheme mining excavation sites to the maintenance of development workings behind the working face. However, this involves a challenge to ensure their operational status behind the lava zones of influence of clean-up and steady rock pressure, as well as the need to develop effective ways and means of excavation workings, in particular methods of using an ordinary rock and bounding surfaces. Application of methods of using an ordinary rock and bounding surfaces can significantly reduce labor costs by reducing the amount mortgaged species while reducing the cost of maintaining the excavation due to increased carrying capacity of constructed structures. A detailed study of modern means of protection can be concluded that the security installations, regardless of its degree of compliance with time begins to run as a stamp, including ways of using an ordinary rock and bounding surfaces. This circumstance requires the development of measures to neutralize this effect on the stability cutter production, namely, determining the parameters of security installations in which the forces arising from the action of the load on the security installations will not be directed toward the output. In our opinion, this can be achieved using security structures of variable stiffness. And the alarm is supposed to build the design of an ordinary rock in order to reduce the cost of maintaining the cutter production. Goals and ObjectivesObjective: To study how the parameters of excavation workings pedigree supports variable stiffness To achieve this goal it is necessary to solve the following problem:
Alleged scientific noveltyScientific novelty of the work is to extend the concepts of mechanical processes in rock pillars from the bounding surfaces and their surrounding rocks. Expected practical resultsA method of excavation workings pedigree supports variable stiffness. A review of research on the topicTo date, there is a large amount of DonNTU studies of stress-strain state of the ambient array and proposed a sufficiently large set of measures to preserve stability of the excavation workings through the management of his condition. Among them, for example, can be identified:
Within Ukraine scientists consider the following questions in poysheniya carrying capacity of security structures:
Browse by topic outside of Ukraine showed that carried a lot of research to increase the carrying capacity ohrnnyh facilities, and also the problems of modeling these systems. The main part ofIn 60-70% of cases, the poor state of workings, supported behind the lava rocks due to intense displacements of the soil. Polysyllabic process of swelling rocks soil determines a wide range of ways to combat it. And, as practice shows, some only way to prevent heaving rocks at the increasingly complex conditions of the soil layers is not enough working out, and to ensure sustainability of production need to address its maintenance and protection in the complex. Moreover, well-chosen method and means of protection are the most effective way to reduce the cost of mounting and maintaining excavations [1]. Very often a means of protecting themselves (rubble strips BZHBT, cast strips, etc.), namely, the scheme of their installation and placement on the formulation, are causes intense swelling of the rocks of the soil, and these structures play the role of the stamp, from under which rock squeezed into the cavity production [2, 3]. Thus, the development of methods and definitions of their parameters should include number of studies of stress-strain state (SSS) surrounding the array. The development of computing technologies has led to the creation of a large number of programs that use the most common method for analysis of stress-strain state - a finite element method (FEM). Modern computer technology allows us all the easier to simulate and calculate the various mechanical systems. To accomplish this, there is still quite a large number of software environments running in one direction or another. This paper was selected program to build 3D models for strength analysis - SolidWorks 2009 with built-in billing module CosmosWorks 2009. In the simulation model are the soil excavation under the action of her uniformly distributed and unevenly distributed load on a rectangular platform in the analytical SolidWorks Design and solved the problem of statics in the linear formulation by means of a package finite element analysis CosmosWorks. We consider two variants of mining:
Pic.1 - General view of the security structures (rubble strips) with a uniform load distribution across the width of the strip
Pic.2 - General view of the security structures (rubble strips) of variable stiffness
Kinematic boundary conditions can be specified on the faces, edges and vertices. In processing the faces of the canonical form - flat (Plane), cylindrical (Cylindrical), or spherical (Spherical) - the program "feels" their shape and boundary conditions are applied in the light produced by these objects of ways. In the simulation used the following boundary conditions: - Fixing (Fixed) - fixed geometry. Fixation movements in all directions of the lower base of the model. As well as the prohibition movement in the horizontal direction, with a free sliding in the vertical direction at the sides of the model. Static boundary conditions - is power. They can be focused and have a dimension of "power", distributed along the edge of the "force / length", distributed on the surface of "the force / area." The latter include the pressure. In the simulation used types of static boundary conditions. Directional constant pressure - perpendicular to the selected face. Consider the details given in the simulation boundary conditions. The top of the model, there are five rectangular areas. From the width of area equal to the width of one strip in the rubble zone - one meter. The length of the rectangular area is 10 meters in order to keep a proportion of 1:10 and in the future to consider the plane problem. When considered traditional rubble strip with the same degree of compliance, for each of the areas applied uniformly distributed load of 100 MPa (pic. 3). 
Pic.3 - Scheme of loading 100-100MPa
When considered security installations of variable stiffness (variable compliance), the first platform was attached load 100 MPa, and the subsequent (2-5) is uniformly decreasing load, depending on the model under investigation (pic.4). 
Pic.4 - Animated load distribution of the underlying rocks
Animation is implemented using Adobe Photoshop CS3: the number of frames - 4, the number of cycles of repetition - 7, the volume of 151.677 KB
To determine the parameters of the proposed method would be appropriate to use the system Plaxis, which is a specialized two-dimensional computer program based on finite element method, which is used to calculate deformation and geotechnical stability of various objects. The real situation can be simulated by the model of plane strain or axisymmetric models. The program has a user-friendly graphical interface that allows users to quickly create a geometric model and finite element mesh based on the presented vertical cross-section. Create two-dimensional finite element system in Plaxis is based on a geometric model. This model is created in the xy plane in a coordinate system, whereas the z-direction is out of the plane. In the coordinate system z-direction shows the direction of the user (pic 5). 
Pic.5 - Coordinate system and positive components of the stress
In all cases, input, output, and power compression stresses are negative, whereas the tensile stresses and forces are positive. In Plaxis software system we calculated the number of models, each of which provided security installations of variable stiffness, but at a different location on its relation to the development. To calculate the models in the program input Plaxis created a two-dimensional virtual model. It is filled with material parameters close to real conditions. At the initial stage of the first model was worked out. Then, at the upper bound of the model was applied distributed load of 10 kN/m2 and make calculations for determining the vertical stresses and displacements. The following models were created based on first removing the protective structure of production. ConclusionThe analysis of unconventional ways to increase the stability of the excavation excavations showed that the main trend of development aimed at creating conditions under which the forces arising in the vicinity of production would be directed away from the most production in order to minimize their impact on the stability of the latter. Important NoteIn writing this essay master's work is not completed yet. Final completion: December 2011 Full text of the materials on the topic can be obtained from the author or his manager after that date. Literature
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