Abstract Kurdjumov DN Ground of parametersof mineworkings support metchod, which presupposes the construction of rock pillars of variable rigidity.

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Kurdjumov Dmitrey Nikolaevich

Institute of Mining and Geology
Speciality: Mining of mineral deposits

Theme of master's work:

Ground of parametersof mineworkings support method, which presupposes the construction of rock pillars of variable rigidity.

Scientific adviser: Negrey Sergey Grigorevich

About author

Abstract

Introduction

Improving the competitiveness of coal as the main energy source in Ukraine, connected with the decrease of its cost. The most of the cost is the mining-preparatory work. One way to reduce these costs is the use of systems development with repeated using of mineworkings.

Actuality

The important question is the protection of extraction mineworkings in the zone of influence of stope works. Developed a multitude of ways and means of mineworkings protection. But the universal way, applicable to any geological conditions do not exist. It is necessary to develop new or improve existing methods of protection, taking into account the conditions in which they apply. For example, in the strict protector installations, with the traditional scheme of arrangement (Fig. 1a) is not recommended for weak soils, they play a role

Fig.1. Location security installations along a generation 3, the traditional (a) and proposed (b) location of security installations, where a - the width of the protective construction , b - width of the compensation cavity between the protective construction, D - width of mineworkings, C - the length of the security construction.

of the "punch", squeezing the underlying rocks in the cavity output. It is proposed (Fig. 1b) security devices (2) to construct near the mine mineworkings (1) in the form of free-standing rectangular parallelepipeds between them form a compensation chamber (3). Due to this layout we can redirect the swelling soil from the mineworkings to the compensation cavity. The question of the influence of parameters of this method on the magnitude of the displacement of soil and rocks of the roof making has been not studied.

Objective

The aim of the article is the studying the influence of parameters of the proposed method on the magnitude of the displacement formulation of the enclosing rocks. This is useful to refer to a laboratory simulation.

The most appropriate method of modeling for solving this problem is the method of equivalent materials [1]. In the first stage of modeling the goal was to compare the nature of the displacement of rock ground simulated production if protect devices were solid and discrete. In the first (Fig. 2 left side) the construction located at the wall, on the both sides of it

Fig.2. Arrangements of protection construction in the model.

In the second (Fig. 2 right side) - supporting elements were mounted perpendicular to the longitudinal axis of generation. Between the supports provided the compensation cavity.

Loading a model with pressure P = 0.01 MPa, the traditional location protection construction, there was uplift of rock ground production, and loading with pressure P = 0.04 MPa, there was complete destruction of the soil of mineworkings Fig.5 (1). In the proposed scheme the displacement of rock ground observed relatively later, and their magnitude was significantly lower

Fig.3. Location of protection construction along the mineworkings in the model.

Fig.4. The model in the process of mining.

Fig.5. Graph of displacement of rock ground in the traditional two-way (1) and proposed (2) the location of security installations.

Fig.6. Graphs of the displacements of the soil layer in the mineworkings (1) and in the compensatory cavity (2), depending on the current load.

Three models with different parameters of protection constructions were prepared to determine the optimum ratio of the width of the supports and the width of the compensation cavities.

The first model (Fig. 7, 8) with scale of modeling 1:100 was divided into three sectors.

Fig.7. Location protection constructions (1) compensating cavities (2) along the mineworkings (3) (where a is the width of the protective structure, b is width of the compensation cavity between the protection constructions, D is the width of the mineworkings, C - length of the protection constructions).

Fig.8. General view of the model before its stressing (where 1 is the protection constructions, 2 is the compensation cavity).

In each sector, the distance between the protection constructions b was taken equal to the thickness of layer m, and the breadth of security structures and was adopted: first sector a = m, a / b = 1, in the second sector a / b = 1 / 2 and in the third - a / b = 2.

Fig.9. Type models with a ratio of width of pillars and cavities of a / b = 1 (as) and a / b = 1 / 2 (b).

The results of modeling were obtained graphs of the magnitude of displacement of rock ground cavities on the value of additional load due to different ratios of a / b (Fig. 10).

Fig.10. Graphs of the displacement of rock ground compensatory cavities U / m on the magnitude of the additional load due to the reliance q at various ratios of a and b.

Analysis of simulation results showed that the width of support less than the width of the cavity (the ratio of a / b = 1 / 2), the shift reaches the value 0,28 m, and then going on puncturing the underlying rocks, with the width of the support with a ratio a / b = 2 the heaving is practically not observed (no more than 0,02 m). The largest heaving is observed at a ratio a / b = 1 and accounted for 35% of the power of the layer, and then also happened puncturing of the soil. Thus, from the graph that optimum ratio of the widths of the supports and cavities, in terms of stability of rock ground of mineworkings, in which displacement in the cavities will be maximized for the conditions considered to be 1:1. The goal of the which is to compare the qualitative picture of the mining pressure in the tra next stage of modeling is comparing the pictures of showing of the mining stress for traditional and proposed protection constructions.

There were prepared two models (Fig. 11,12) with a scale model 1:50. Methodology of the experiment conforms to the requirements

Fig.11. Scheme of the simulated plots of the mineworkings in the traditional (a) and proposed (b) methods of production.

Animation 1. The nature of the deformation model in the time of processing.

Animation. The nature of the deformation model in the time of processing. (Made in Adobe Photoshop CS2, 7 cycles, 7 frames, delay 0.3 sec., Size 108 KB)

Fig.12. General view of the mineworkings in the models (a) before and after being subjected to (b) the traditional (left-hand side of figure) and proposed (right-hand side of figure) methods of protection.

Fig.13. The displacements of the roof rocks (1,3) and soil (2,4) in the traditional (Figures 1,2) and proposed (Figures 3,4) ways of protection.

[1,2]. As a result of mining models received a graph of the displacements of the roof rocks and soil in the traditional and proposed methods of protection.

Findings

The proposed location scheme of protection constructions is more effective than the traditional, as from the standpoint of stability of soil mining, as well as in terms of stability of the roof.

Thus, the proposed method of production makes it possible to use hard structures in weak soils. On models of equivalent materials have been identified its basic parameters, and efficiency compared with the traditional method of protection.

At present currently work is under development. Detailed information can be obtained from the author (Kurdjumov D.M.) or his scientific supervisor (Negrey S.G.) in January 2011.