JUSTIFICATION OF THE FORMS AND DIMENSIONS OF INJECTION HARDENING ZONES UNDER CONDITIONS OF ASYMMETRICAL LOADS ON UNDERGROUND STRUCTURES

Problem statement. For conditions of asymmetric loads on underground structures caused by uneven weakening of rocks due to flooding and other natural and man-made factors, issues of substantiating rational forms and sizes of injection hardening zones require further comprehensive studies combining geomechanics, materials science and optimization methods. Purpose of the study. Justification of the parameters of injection rock hardening zones to improve the safety level of underground workings and buried structures under conditions of asymmetric loads on the support. Methods. Generalization of data on the asymmetry of loads on the support of underground structures; methodology for assessing the rock massif destruction; mathematical modeling using the finite element method. Research results. Hardening of rocks around underground workings and buried structures allows to reduce the probability of cracks, prevent the development of deformations and increase the overall resistance of objects to the impact of operational and natural loads. The issue of substantiation of rational forms and sizes of injection hardening zones for conditions of asymmetric loads on underground structures which are caused by uneven weakening of rocks due to flooding and other natural and man-made factors requires further research. The features of the formation process of loads asymmetry on the support of the underground structures are determined. The method of assessing the state of the polymer-saturated rock massif and forecasting its changes under the influence of certain measures to strengthen the rocks around the underground structure is substantiated. It has been established that rock hardening by means of injection and other hardening technologies allows for effective compensation of supporting deficiencies without a significant increase in capital expenditures. In addition, the use of various configurations and arrangement schemes of hardening zones allows for flexible adaptation to specific geological conditions, redistribution of stresses in rocks, reduction of their concentrations in potentially hazardous zones, prevention of local collapses, deformations and water inflows, which ensures long-term safe use of underground structures. For conditions of uneven loads on the supports, an asymmetric shape of the hard-ened zone is proposed, which can be used as a reserve for increasing the stability of the underground structure. It is established that the nearly elliptical shape of the hardened zone as an element of rock pressure control ensures an in-crease in the stability of the underground structure due to a 10‒35 % reduction in the inelastic deformation zone and a 0,5‒3,0 m deep displacement of the asymmetric support pressure zone. The displacement of the roof of the underground workings is reduced by 6‒13 % of the total displacements, and the workings floor by 7‒23 %. Scientific novelty. For the first time, in order to increase the level of safety in the operation of underground workings and buried structures under conditions of asymmetric loads on the support, patterns of changes in maximum principal stresses have been established when using various nearly elliptical shape of injection rock hardening zones. Practical significance. The proposed configurations of injection hardening zones reduce stress concentrations in rocks, which helps prevent sudden deformations of supports and ensure long-term safe use of underground structures.