RU2606729C1 - Strengthening method of hardening filling mass - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: invention relates to mining industry and can be used in development of mineral deposits with stowing mined space. Method of hardening of filling mass, which involves placing in formed array of reinforcing elements simultaneously with hardening mixture used reinforcing elements are modified basalt microfibre (MBM) in amount of 7.1 % of binding substance weight. Microfiber contains, wt% basalt wool with organic impregnation – 99.3–99.6, carbon nano structures of fullerene type – 0.00001–0.01, water – rest.

EFFECT: technical result is provision of safe conditions of mining operations at increase of strength of filling for tension.

1 cl, 2 tbl

Description

The invention relates to the mining industry and can be used in the development of mineral deposits with the laying of the developed space.

A known method, comprising feeding a mixture with a different binder content to the spent chamber, in which the chambers are laid with mixtures containing binders, is produced in its lower part to the level of the upper boundary working out of the underlying horizon, then the bookmark is laid with mixtures without binders to the level of the drilling horizon soil, after shrinkage of the embedded layer, filtration and evaporation of water around the perimeter of the chamber; a reinforcing structure is placed in the shrinkage slot; wells are drilled in the embedded array along the chamber walls to the mark, finding below the upper mark of the bookmark layer in the lower part of the chamber, part of the array between the walls of the chamber and the walls of the wells is destroyed, reinforcing bars are inserted into the wells in excess of them above the level of the laid mass, then the wells and the filling gap are poured with a solution containing binders, after which the upper part of the chamber filled with a mixture of binders (RF patent No. 2367797, published September 20 , 2009).

 The disadvantage is the large complexity of the work, the uncertainty in the strength of the formed array, the high consumption of expensive reinforcement and the uncertainty in the level of safety when it is placed.

A known method of hardening the filling array with reinforcing material in the form of pieces of metal wire. The method consists in the fact that increasing the stability of the outcrops of the backfill array is achieved by simultaneously placing the reinforcing material in the form of pieces of metal wire and the hardening mixture in the zones adjacent to the exposed surfaces of the backfill array (USSR Author's Certificate N 663855, published on 05.25.1979)

The disadvantage of this method is that the reinforcing material supplied to the zone of exposure of the array is distributed unevenly in the filling array, which leads to a decrease in its strength, since in places of accumulation of metal segments as a result of their contact with the aggressive environment, their corrosion occurs, which destroys the structure concrete.

A known non-shrink composition for repairing concrete road, bridge and airfield coatings (RF 2362752 published July 27, 2009), which contains 0-7% by weight of a nanomodified basalt microfiber binder, on the surface of the fibers of which ultrafine carbon nanoparticles with a linear size of about 50 100 nm, in an amount of 0.005-0.010 wt.%, And water contains 0.1-0.2% by weight of the binder.

The disadvantage is the high complexity of the work due to the large number of components, the impossibility of a mechanized supply of material into the worked out space and uniform spreading in the worked out space.

The closest is the method of hardening the filling array, including placing reinforcing elements in the formed array simultaneously with the hardening mixture, characterized in that in order to increase the resistance of the filling array to fracture when combined with alternating tensile and compressive forces, basalt fiber in the amount of 4 is used as reinforcing elements 5% by weight of the hardening mixture (RF patent No.2019712, published September 15, 1994).

 The disadvantage is the large number of reinforcing elements, which limits the mobility of the mixture, excluding its transportation through pipes and spreading in the filled chamber. This mixture can be delivered to the chamber only by bucket loaders or dump trucks and stacked manually, which will lead to the complication of the technological scheme, the cost of work and lower safety.

The task of the invention is to ensure safe mining conditions while increasing the tensile strength of the bookmark.

To solve this problem, a method for hardening the filling array is proposed, which includes placing reinforcing elements in the formed array simultaneously with the hardening mixture, and modified basalt microfiber (MBM) in the amount of 7.1% by weight of the binder is used as reinforcing elements.

The technical result consists in the mechanized supply of reinforcing material, the creation of safe mining conditions while increasing the strength of the filling mass under tension and crack resistance while maintaining the consistency of the mixture suitable for transportation through pipes and spreading in the worked out space.

MBM (TU 5761-014-13800624-2004) manufactured by CJSC Astrin-Holding consists of (in% by weight):

- basalt cotton wool with organic impregnation - 99.3-99.6;

- nanomodifier −0.0001-0.01;

- water - 0.3-0.5.

As a nanomodifier, a carbon nanomodifier of the fulleroid type is used according to TU 2166-001-13800624-2003.

The main characteristics of MBM are shown in table 1.

Table 1 No. Name of indicator Norm one The average fiber diameter, microns 8-10 2 The average fiber length, microns 100-500 3 The content of non-fibrous inclusions,% by weight, not more than 10 four Humidity,% by mass, no more one 5 Bulk density, kg / m ³ , no more 800 6 Organic matter content,% by mass, not more than 2

The method of hardening the filling array is as follows. The artificial massif is formed from a hardening filling mixture, into which reinforcing elements — microfiber basalt modified MBM, are fed into the worked space before being laid. The hardening mixture is transported to the place of formation of the array through pipes and fed into the chamber. When spreading the filling mixture over the developed space, MBM fibers are distributed evenly throughout the entire volume of the future artificial massif and block the growth of cracks, the formation of which is facilitated by the low tensile strength of concrete. This can significantly improve tensile strength.

To test the efficiency of the proposed method, a model of the filling array was made, consisting of a binder, aggregate, superplasticizer, water. Two series of the array were made: In the first series of the (control) microfiber, basalt modified MBM was not added. In the second series, 7.1% by weight of the binder microfiber of basalt modified MBM was introduced into the mixture. Samples were formed from both series of the array. After 90 days, samples of 40 × 40 × 160 mm were tested for tensile strength in bending using an Instron 5882 electronic testing machine.

In addition, we evaluated the tensile strength of the samples at the age of 180 days using the splitting method using an Instron 5882 electronic testing machine.

 The values of tensile strength obtained by this method in all cases very closely coincide with the values of axial tensile strength. (Stolnikov V.V., Litvinova R.E. Crack resistance of concrete. - M: Publishing House Energy, 1972. - 113 pp. –39-41 p.).

The test data are shown in table 2.

table 2
Experimental data Series No. The number of MBM,% by weight of the binder Suttard spreading spot diameter, mm (flowability) Tensile strength in bending, MPa The tensile strength by splitting, MPa Fracture toughness coefficient 1 (control) 0 210 2,685 0.399 0.431 2 (proposed) 7.1 174 3.06 0.540 0.547

To ensure a stable mode of transportation through pipes and uniform stacking in the worked-out space, the following recommended flowability of the mixture is 13–20 cm (Montyanova AN 2009. Formation of filling arrays during the development of diamond deposits in the permafrost zone. M., Mountain Book, 597 pp., p. 308).

From table 2 it follows that the task is to ensure safe mining conditions and the mechanized supply of reinforcing material while increasing the bookmark tensile strength and crack resistance of the array while maintaining the consistency of the mixture, suitable for transportation through pipes and spreading in the worked out space, is achieved by introducing microfiber into the hardening mixture basalt modified MBM in the amount of 7.1% by weight of the binder.

Claims (2)

A method of hardening a backfill array, comprising placing reinforcing elements in the formed array simultaneously with a hardening mixture, characterized in that basalt microfiber modified in the amount of 7.1% by weight of the binder is used as reinforcing elements, said microfiber containing, in mass. %: Organic basalt cotton wool 9.3-99.6 Carbon nanomodifier of fulleroid type 0.0001-0.01 Water 0.3-0.5