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Institute of Mining and Geology

Department of Mines and the construction of underground structures

Speciality "Mine and underground construction"

Justification of parameters fix vertical trunks of deep coal mines

Scientific adviser: c.t.s., assistant professor Ivan Kupenko


Abstract on the Master`s work


Contents


Introduction

1 Purpose and objectives

2 Prosed scientific novelty

3 Estimated value of practice

4 A review of current research

5 List of unsolved problems

6 Deliverable

Conclusion

References


INTRODUCTION


Coal mining in Donbass can't be effective without investments into a coal-mining complex. It is conventional that mortgaging cost of the enterprise is proportional to its capitalization from which appeal of the enterprise to potential investors and creditors, return depends on issue of its securities. Today conducting economists of the western countries in the conditions of the market consider as a main goal of activity of the enterprise any more profit, and growth of its market price which directly depends on capitalization. Most enterprises of coal industry(including almost all state mines) are unprofitable, but however get from the state budget solid grants on coverage of expenses on different directions, including on a technical rearmament. Indicators of work of branch thus stably worsen, as the main source of capitalization – an additional product – in these conditions isn't created, there is no also own profit of the enterprise on production realization.

Reconstruction of the most perspective mines with obligatory increase in capacity and complete technical re-equipment, and also construction of new mines can become one of the directions of reforming of coal mine. It is obvious that realization of these actions will demand activization of activity of the research and design organizations in the direction of development of technology of coal mining on big depths. Maximum for mines of Ukrainian of Donbass depth of conducting mining works makes at present about 1400 m, and by estimates of some experts, it can already exceed 1700 m in the next years.

It is known that the most important subsystem of coal mining in the underground way are tunnelling works on building of capital developments. The special place in practice of their construction on the functional importance and technological specifics is occupied by vertical shaft of different function of which share it is the share to 30 % of cost and to 50 % of the general time of construction.

The constant increase in the depth of mining in the Donbass today raises the specialists in the construction of a number of additional shaft of problems of scientific, technological and organizational measures. Despite considerable financial and material inputs on a construction and maintenance of trunks, and, first of all, on fastening, according to results of researches of experts of UKRNIMI, NIIOMSHS, over 50 % of shaft of coal mines of Ukrainian of Donbass have violations support. It is considered that the main reasons for deformation lining shaft along with complexity of mining-and-geological conditions, discrepancy of technology of fastening to the project, and also not accounting of features of manifestation of mining pressure and the amplified influence of heterogeneity of the pedigree massif increasing with depth of asymmetry of loads of a shaft and other factors are.

The analysis of researches of the last years in the sphere of mechanics of rocks and underground constructions allow to approve that increase of stability lining shaft it should be carried out not at the expense of growth of its material capacity as costs of fastening at a driving of shaft are very essential and can reach 80 % of their cost. Increase in thickness the in the most widespread on practice monolithic concrete lining on 10 cm leads to growth of cost of a shaft by 15 %, and a consumption of concrete – for 30 %

Therefore, there is an urgent need in development of new technological decisions on fastening of shaft; improvement of settlement techniques, especially regarding the accounting of a factor of an asymmetry of loadings on lining which role will grow with depth of a shaft.


Combined diagram of sinking a vertical shaft

The solution of this problem and will be devoted to this work. The foregoing suggests that its importance is beyond doubt.


1 PURPOSE AND OBJECTIVES


The purpose of the work is to establish rational parameters of the concrete lining vertical shafts.

Objectives of research:

  • analyze the literature on the topic of this paper;
  • using statistical methods to establish the value of deviations form the cross-section of vertical shafts from the project (round), depending on their diameter and depth, using actual data from 110 Ukrainian Donbass shafts;
  • using finite element models to establish features of the stress-strain state (SSS) of the "concrete lining the shafts – an array of species",taking into account technological errors in the mounting hole concretes of different classes and ages in a variety of mining and processing conditions of penetration;
  • based on the studies offer recommendations for determining the optimum thickness of the concrete lining the shafts, depending on its depth, diameter, the parameters of the enclosing rocks and the physical and mechanical characteristics of concrete.
    •

2 PROPOSED SCIENTIFIC NOVELTY


Expected scientific novelty of the paper is:

  • the establishment of the deviations of the vertical cross-sectional shape shafts Ukrainian Donbass from the project (round), depending on their diameter and depth;
  • to establish the features of the system of SSS, "the concrete lining the shafts – an array of species", taking into account technological errors in the mounting hole concretes of different classes and ages in a variety of mining and processing conditions of penetration.
    •

3 ESTIMATED VALUE OF PRACTICE


Expected practical value is to develop recommendations to identify the optimum thickness of the concrete lining the shafts, taking into account technological errors in mounting, depending on its depth, diameter, the parameters of the enclosing rocks and the physical and mechanical properties of concrete.


4 A REVIEW OF CURRENT RESEARCH


Established scientific and technological base, has provided real progress in the design, penetration, use of different types of powered roof supports shafts, choosing measures for their protection, etc..

However, for a long time seen a stagnation in the growth dynamics of techno-economic parameters (TEP) for the construction of vertical shafts, a long time is not observed the development and improvement of technological schemes of sinking shafts, there is no hardware upgrades. All this is clearly contrary to international trends of mine construction.

Obviously, the reliability of the shafts lining shall be provided at all stages of their construction, operation and liquidation. At the same time, as shown by prolonged observations of the state of vertical shafts of Ukrainian and Russian Donbass [1,2], an average of about 50 % of them have a violation, and fastening reinforcement of varying severity.

This situation is absolutely unacceptable, since the construction of vertical shafts is the longest - up to 50% of the time of construction of a modern mine and expensive process – it accounts for 30% of the estimated cost of construction of the mine [3]. The term is often equal to the operation of the barrel service life of the mine. Any violation of bolting or reinforcement in the operation not only require significant costs for their removal, but also necessarily lead to a variety of disruptions in the mining enterprises until the complete cessation of the issuance of the mineral to the surface.

It is considered [1], that the main reasons for deformation lining shafts are:

  1. Difficult, unpredictable mining-and-geological conditions.
  2. Discrepancy of technology of fastening to the project.
  3. Discrepancy of technology of fastening to the project.
  4. Not accounting of asymmetry of loads of a shafts, which degree grows with depth.
  5. Other factors.

The choice of methods of fastening vertical shafts in structurally non-uniform breeds devoted his doctoral dissertation, V. Levitt [1]. The author [1] in particular, established new patterns of interaction between different types of powered roof supports complex structure stems from the rock mass at various kinds of control actions on them, we give a new representation of quantification of the interaction of the trunk lining with layers r different in capacity and different strengths of rocks under various conditions of loading and the contact and obtain quantitative rates of formation of zones of disintegration of rocks on long sections of shafts lining.

Questions of construction shafts in complicated geological conditions (increased water production) were considered in S. Borschevsky [4]. In particular, the author [4] a set of basic informative parameters of the system "technology – concrete lining – water-saturated rock mass", resulting in the selection of the dominant place of indicators to be considered in the development of technological schemes of construction of the vertical shafts have been found of the formation of the marginal to the shafts moist rocks geo-active zones violations carried out their analytical description, defined in quantitative terms, and increase the strength of the concrete hydrofirmness lining shafts.

In V.Driban's works [5] questions of ensuring protection of excavation without repair and operation of vertical shafts in difficult mining-and-geological conditions in particular were considered. On the basis of results of long-term scientific researches, the author [5] пreceived the following practical results: the new method of an assessment intense the deformed condition massif of the rocks, considering all major mining-and-geological, mining and geomechanical factors is offered; criteria of stability of the massif are given and lining mine shafts; the method of calculation is developed lining mine shafts; the package of measures, vertical mine shafts providing stability in difficult mining-and-geological conditions is offered.

Method for calculation of the shafts lining of variable thickness (taking into account the asymmetry load) is shown in the works O. Bykova [6].The author [6] ], in particular, we solve the contact problem of elasticity theory for rings of variable thickness; developed computational schemes for various types of powered roof supports shafts with their variable thickness. This allowed a more defensible given design lining of variable thickness to increase its resistance to stress-sided, for the first time to introduce a differential coefficient of the working conditions of the concrete lining in SNIP "Underground mining".

Attempt of the accounting of discrepancy of technology of fastening to the project and arising thereof asymmetries of loadings on concrete lining a shafts is undertaken in M. Prokopova's works [2, 7–11].

We will list the main results received in below [2].

  1. According to the results of statistical data processing on 74 shafts of the Russian and Ukrainian Donbass:
  • influence of diameter in light is established and depths of a shafts on size of radial deviations of walls lining a shafts from design situation (fig. 1), the nomogram for definition of the maximum average radial deviations monolithic concrete is constructed lining a shafts depending on its diameter and depth;
  • define the nature of the influence of radial deviation of the walls lining the shafts of the project status to the performance of the lining;
  • identify trends in the shafts cross-sectional shape with depth.

Nomogram

Fig. 1. Nomogram for determining the maximum and average ΔRmax and ΔRmd radial deviation of monolithic concrete lining the shafts, depending on its diameter D and depth H [2]


  1. At 96 the finite-element models (Fig. 2) study changes in SSS, taking into account deviations from the walls lining the shafts of a project, depending on the type of host rock, depth, diameter and thickness of the lining of shafts and identification of the most unfavorable combination of factors.
  2. Methodological recommendations for calculating and designing roof support and reinforcement, taking into account the probable deviations from the shafts lining of the project and form.

БIt was proposed to introduce in the calculation of the thickness of lining coefficient of stress concentration of km in places thinning rings, arising as a result of the inevitable technological errors. With its view of the regulatory formula for calculating the thickness of lining takes the form:


formula

где my – the coefficient of working conditions bolting taken equal to 1,25; r0 – radius of the vertical production in the light, mm;; m61, m63, m67 – respectively, the coefficient taking into account the long-term stress, a condition for the growth of strength and temperature fluctuations; Rпр – the design strength of concrete compression, kPa; kр – stress concentration factor in the design of roof support, taken equal to 1 on the extended parts of the trunk and to (2 – 0,05z) in the interface, where z – distance from the site prior to the coupling section, m; P – the horizontal pressure on the lining, kPa; σпб – thickness porodobetonnoy shell formed by the penetration of the concrete surrounding the broken rock.


Example of finite element models

Fig. 2. Example of finite element models [2]: а – general view, б – fragment of the lining


5 LIST OF UNSOLVED PROBLEMS


As shown by an overview of the literature to date not fully, in our opinion, the influence of physico-mechanical properties and age of the concrete lining the trunk lining on the SSS system, taking into account an array of abnormalities of the walls lining the shafts of the project status. This is especially important when using a combined flowsheet sinking shafts, which is used in our country most frequently (98%). As is well known [3] , ], the most significant drawback of this scheme is that a set of concrete strength is in the bottom-hole area at the time of redistribution of rock pressure and intensity of the displacement of rock walls. In the same paper [2] on the finite-element models of the concrete was investigated only one class – В25, and its characteristics were set at 28 days, when scored 100% strength.

We believe that more research is needed VAT system "lining-array" taking into account the deviations of the walls lining the shafts of the design provisions for concrete B15 (the most frequently applied in the domestic practice of lining shafts), and B20, including the age corresponding to the time of removal formwork, including depths exceeding 1,500 m.

It is also necessary to construct a similar figure. 1, a nomogram for determining the maximum average radial deviation of monolithic concrete lining the shafts, depending on its diameter and depth of the analysis of additional data - for 110 shafts of Ukrainian Donbass.

In this case, the stress concentration facto km will be more close to real conditions of sinking shafts in the Ukrainian Donbass.


6 DELIVERABLE


The results should be to successfully addressing the problems stated above studies that to achieve its goals in this paper.


CONCLUSION


An analysis of the literature identified the purpose and objectives of this master's work.

In Chapter 1 will be made more detailed than the abstract analysis of paragraph 4 of this literature on the topic of this paper.

In chapter 2 using the methods of mathematical statistics are set of deviation form the cross-section of vertical shafts from the project (round), depending on their diameter and depth using the actual data of 110 trunks Ukrainian Donbass.

In the third chapter, using the finite element models will be installed especially the stress-strain state (SSS) of the "concrete lining the shafts – an array of species", taking into account technological errors in the mounting hole concretes of different classes and ages in a variety of mining and processing conditions of penetration.

In chapter 4 on the basis of the research will provide recommendations to determine the optimum thickness of the concrete lining the shafts, depending on its depth, diameter, the parameters of the enclosing rocks and the physical and mechanical properties of concrete.


REFERENCES


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