Faculty: Institute of Mining and Geology
Speciality: Mining of mineral resources
The review of literature allows to conclude that the basic reasons of the mining working support deformation are constant support construction in the area of intensive rock shift, including the use of its carrying elements as a temporary support; unqualified driving works; secondary rock shifts caused by balance breakdown of the rock mass; uncorrespondance of parameters or support construction to mining conditions. The analysis of the given reasons shows: for the improvement of the conditions of mining working support it is necessary to use a carrying ability of the rock mass, creating the system “support – rock” immediately after support construction. This can be achieved by using a rational temporary support. Technical and economical comparison of temporary support constructions allows to conclude that temporary concrete support meets the requirements of the use of the carrying ability of the rock mass most completely. Its use not only can improve the conditions of the mining working supports, and reduce their construction expenses, but it will also arise the driving pace. The great contribution into the development of this method of support was made by the research of the soviet scientists M. M. Aitaliev, S. A. Atmanskikh, L. N. Beliaev, I. L. Voller, V. S. Voronin, D. M. Golitsinskiy, M. G. Duzhenko, Zh. S. Erzhanov, V. Y. Zaslov, E. V. Kazakevich, B. N. Kuzin, G. I. Kravchenko, M. A. Lev, V. M. Mostkov, V. M. Sapunov, P. I. Shylkin, and also foreign researchers R. Linder, H. Liaufer, L. Rabtsevich, R. Shtal. As a result of this research special cements have been created for this type of concreting, the mechanism of the action of the extras for acceleration of concreting has been studied, the basic parameters of this concreting technology have been defined, the machines for the support construction have been created. In addition, the analysis of the works devoted to the mining working support by means of concreting allows to conclude that the questions of the concrete support as a temporary support have not been studied enough. In our work a new decision of the actual scientific problem is given – the survey of the temporary concrete support parameters providing the rise of the stability of the capital mining workings and the decline of expenses for their construction and support.
1. It is concluded that the basic reasons of the mining support deformation are constant support construction in the area of the intensive rock shift, including the use of its carrying elements as a temporary support; unqualified driving works; deformations caused by secondary rock shifts; uncorrespondance of the parameters or the support construction to mining conditions. The analysis of these reasons shows: for the improvement of the conditions of mining working support it is necessary to use a carrying ability of the rock mass, creating the system “support-rock” immediately after support construction that can be achieved by using a rational temporary support.
2. The strength abilities of the concrete at the early stage have been defined. This allowed to define its optimal mix for a temporary support – C : S (cement - sand) = 1:3 with the addition of fluorinate sodium (4 percent from the mass of cement) or silicate sodium (6 percent from the mass of concrete) as an accelerator of setting. The strength of the concrete in compression after an hour after addition of water to a concrete mix is MPa.
3. It is defined that the temporary support concrete destruction at its loading by the rock inrush happens in a way of shearing around the opening in a concrete covering is 2 mm. With the account of this the dependence of values of critical shifts of the roadway network from its width for a temporary concrete support has been defined. For roadway of 3,0 – 5,5 m wide the values of these shifts change from 38 to 87 mm.
4. At the constructing of the temporary concrete support the concrete penetrates the cracks of the rock mass and strengthens it. For the account of simultaneous work of the concrete support with the reinforced rock layer we have got the dependence of the depth of the reinforcement of the mass near the shearing from the concrete mix and the width of the crack opening at the roadway shearing. The maximum depth of the reinforcement reaches 16 cm.
5. The parameters of the temporary concrete support has been defined – its thickness and the expiry period. The thickness of the support was defined providing its balance at the loading by the rock inrush and at working in shear. The expiry period (the period of time since the moment of its construction till the moments of the constant support construction) is defined with the account of the reinforcing effect of the concrete at the condition that it is equal to the time of the realization of the critical shift. The area of the aimed use of the temporary concrete support is capital mining workings constructed out of the area of the direct influence of the clearing works at the even or inclined position of rock in the conditions where ðgH/á<=0,5.
