Experimental Studies of Deformation Characteristics of Mine Protection Structures

Abstract

The purpose of the article. Studying deformation characteristics of protective structures under the influence of external loads used to maintain lateral rocks in the coal massif behind the production face. Methods. To achieve this goal, laboratory studies of the deformation characteristics of security structures under uniaxial compression were performed. Results. As a result of the research it has been established that at uniaxial compression of wooden protective constructions in the form of rolling fires from sleepers or bushes from risers, change of their rigidity is caused both by differences in properties of wood at action of external force along or across fibres, and design features. In cases where a constant compressive force is applied to the experimental sample across the fibres (rolling fires from sleepers), the change in stiffness is quadratic and reaches minimum values when the deformation of the model by 30-35%, and with a further increase in deformation to 50% stiffness increases. This indicates an increase in the resistance of rolling fires to external loads after their compression, without losing the strength of the structure. Under the action of compressive force along the fibres (bushes of risers), the stiffness of the experimental samples increases until the moment of destruction, when there is a loss of strength of the structure. The change in the stiffness of embedded arrays of crushed rock, if possible, their lateral expansion occurs due to the compaction of embedded material, i.e. recomposition of particles of crushed rock of different fractions in the total volume. Novelty. The nature of the deformation of security structures considered as prefabricated structures can be described by the change in the specific potential deformation energy spent on changing the shape and/or volume of the protective structures. Practical meaning. To ensure the stability of the side rocks in the coal massif containing the workings, it is necessary to focus on the use of flexible protection structures located above the retractable roadway.

Evaluation of the effectiveness of secondary support of haulage drifts based on a comparative analysis of the deformation characteristics of protective structures

“…= 1790 kg/m 3 with hollowness M = 15 %. Poisson coefficient ν = 0.25 [14]. Roofing and sole rocks were modeled as a slab l s = 0.3 m long, b s = 0.1 m wide and h s = 0.03 m thick.…”