Purpose. Investigate the deformation properties of structures made of ground rock under static load conditions to preserve the integrity of the side rocks in the produced space of the coal massif and the operational state of the preparatory mine workings along the length of the excavation site. Methodology. In laboratory conditions, experimental samples of protective structures made of ground rock of heterogeneous granulometric composition were subjected to static loading under conditions of uniaxial and compression compression. Results. It was experimentally established that under the conditions of uniaxial compression of protective structures made of ground rock with the possibility of its lateral expansion, the effect of forming the bearing capacity is manifested in the relative change of the volume of the embedded material in the range of values , when, after increasing the relative deformation, the resistance reaches the maximum compaction of the rock . In such conditions, it is necessary to ensure the stability of the bearing pillar of the embedded material. During compressive compression of crushed rock, such an effect is achieved in conditions where the relative change in the volume of the embedded material is . After maximum compaction , the resistance of protective structures increases. Scientific novelty. The type of functional dependence between the relative deformation is established protective structures made of crushed rock and relative volume of the embedded material under static load under uniaxial and compressive compression, which allows to evaluate the bearing capacity of flexible supports. Practical significance. In order to assess the stability of protective structures made of crushed rock, which are in different compression conditions during the unloading of coal massif, it is necessary to take into account the compaction coefficient of the original material and the longitudinal deformation of the support under load. Keywords: coal massif, guard building, ground rock, uniaxial compression, compressive compression.