Determining the efficiency and parameters of rubble strip reinforcement

Abstract

The necessity of development and improvement of methods and means for the protection of preparatory roadways, in particular, protective structures, was proved on the basis of ordinary rock with binding surfaces. Analysis of the results of the study on the use of protective structures of ordinary rock and bounding surfaces was performed. It has shown the feasibility of reinforcing rock structures to ensure operational conditions for the protected roadways. Such structures include rubble strips reinforced with partitions made of metal mesh. To determine their efficiency and reinforcement parameters, studies were performed using provisions of structural mechanics, soil mechanics, and bulk media, as well as physical modeling using natural materials. According to the results obtained in the performed studies, the efficiency of reinforcement of rubble strips with a metal grid was proved and a procedure for calculation of reinforcement parameters that need to be considered in designing the above structures was developed. Such parameters include width and height of the strip, class of reinforcement, its diameter and tensile strength, size of the grid cells, angle of internal friction of rocks, and diameter of maximum rock pieces in the strip. It was established that reinforcement of the rubble strip by partitions made of metal meshes can reduce the width of the strip and volume of the rock fill by 1.33…2.66 times without losing the structure rigidity. To do this, the condition of reinforcement strength in grids must be met. It consists of comparing its tensile strength with maximum stresses in the partition. These stresses are determined by the magnitude of the load on the rubble strip from the roof rocks, the diameter of the reinforcement, and the maximum rock pieces, as well as relative extensional strain in reinforcement.

Numerical simulation of the surface subsidence evolution caused by the flooding of the longwall goaf during excavation of thin coal seams

“…Backfilling in Ukraine is carried out mainly for the conditions of ore deposits [37,38]. The theoretical studies are also carried out for coal deposits [39][40][41]. The presented study is planned to develop in this direction.…”