Study of fracture mechanics in heterogeneous rocks, including crack initiation and propagation, has practical applications for geocontrol and identification of fracture zones in hydrocarbon well extraction. The features of microcrack zone formation depending on the type of rock heterogeneity under triaxial stress state conditions are considered. The research was conducted using an MTS 815 servo-hydraulic testing frame integrated with a Milne DAQ acoustic emission system (Itasca International Company, UK). The paper presents the fracture results of samples of various lithological types manufactured from cores of post-magmatic rocks. Fine-grained samples with gneissic and banded textures, as well as a coarse-grained sample with massive texture, were tested. During the tests, acoustic emission (AE) was recorded using 12 piezoceramic sensors. To describe the geometry of the fracture zone, the coordinates of AE event hypocenters were calculated, then the configuration of hypocenters distribution was analyzed using a tomography procedure (layer-by-layer construction of AE event density maps), and the angles β between the direction of the macrocrack and the axial stress σ₁ were determined. To interpret the failure evolution, trends of the b-factor and AE activity were calculated, the intervals of critical behavior of which were correlated with the localization and tomography data. After testing the samples, the types of their deformation and the mechanism of destruction with the phenomenon of dilatation were revealed. It is established that for the considered types of sample inhomogeneities, various microcrack structures are formed under the same volumetric loading conditions. In fine-grained rock of gneissic texture, a linear distribution of AE hypocenters is formed, indicating the formation of microcracks along the direction of layering. For the fine-grained rock with banded texture, the hypocenter distribution is characterized by the formation of distinct clusters, reflecting areas of the most intensive fracturing. In the coarse-grained massive texture sample, a volumetric distribution of hypocenters is observed, manifesting dilatancy properties and the formation of an extensive microcrack network.

In order to study the mechanism of destruction of rocks of various genesis and the formation of fractured reservoirs at great depths, laboratory studies of rock samples in the loading conditions of comprehensive pressure with registration of acoustic emission (AE) and parameters of the process of changing the strength and deformation properties of samples were carried out. The spatial distributions of the hypocenters of AE events for each sample were investigated. By the nature of the distributions, the fracture geometry is described, then visually compared with the position of the formed macrofractures in the samples as a result of the tests. The time trends of the amplitude distribution b, set by the Guttenberg – Richter law, were calculated, which were compared with the loading curves and trends of the calculated AE activity. Based on the analysis of the AE process for three types of rocks – igneous (urtites), metamorphic (apatite-nepheline ores), and sedimentary (limestones) – parameterization of acoustic emission was carried out to determine the features of the deformation process and related dilatancy. As a result, three types of destruction of samples were identified, their geometry and changes in strength and seismic criteria were established.

The results determine the uniaxial compressive strength and the proportional limit for concrete samples with different content and type of polymer fibers.

The methodic of the field observation for the processes of deep benchmark displacements and configuration of the local observing station is offered. The analysis of the results of the field observations for the displacements of the ore pillar is accomplished, the isolines of settling and the isolines of the average speed of settling of the ore massif is offered.

The design procedure of loadings on arch support unilateral rectangular interfaces in an ore file of Jakovlevsky deposit КМА is offered. The settlement scheme corresponds rigid and plastic model of deformation of an ore file in a roof of interfaces. A major factor defining size of loading on overlappings of interfaces, emptiness in a roof after filling there are. Low efficiency of flat overlappings of interfaces on chamber frames and advantages of overlappings of interfaces by arches from profile SVP with horizontal couplers from арматурной steels of armature was revealed. Possibility of operative calculation of loadings and a choice of parametres of overlappings on conditions of durability and stability of bearing elements of support in ores of various types is proved.

Result of numerical modeling of natural in-situ stress formation before and after drainage work is given. Elastic and elastic-plastic material model is used for soil behavior.

According to geological data which was received at the Yakovlevsky deposit, the volumetric model was developed. This model taking into consideration the driving of the mine through zone of weakening. During the analysis of the stress-strain condition near the mine the character of distribution and numerical results of tangential and longitudinal stresses have been revealed. The zone of weakening affects to the distribution of stresses and displacements around the mine. To select the parameters of the lining support it is necessary to take into consideration weakenings and contacts in the ore massive and the distance for these zones.

The results of mathematical modeling of formation of stress fields in stratified rock mass under various vertical and horizontal stresses relation are presented. An assessment of influence of the presence and position of a great geological disturbance on a stress state around a mine working is considered.

Geomechanical forecast of stress-strain state of deep underground subway station is considered. Static work of structures of subway station based on complex approach is shown, including in situ testing and numerical modelling (finite elements method) during different stages of construction.

Survey of 12 typical joints with different types of fastenings was carried out. The actual geometric dimensions of the interfaces and fastening space were measured, the zone of rock squeezing at the sides of the excavation was determined, the operational condition and deformation values of the fastening elements in the area of the excavation interface were assessed.

Рассмотрена проблема взаимного влияния горных выработок в районе их сопряжения. Задача решена математическим моделированием, основанным на методе конечных элементов. Показан характер формирования напряженно-деформированного состояния массива в районе сопряжения выработок. Найдены закономерности распределения вертикальных напряжений и смещений по длине выработок. 

Характер деформирования рыхлых и плотных железно-слюдковых мартитовых руд вокруг выработки с крепью КМП-А3 различен. В плотной руде процесс смещений характеризуется знакопеременными деформациями руды во времени и вглубь массива. Большая часть смещений реализуется через 10-80 сут. Размеры зоны деформаций рудного массива в лежачем боку (1,2-1,3)R_пр, в кровле (1,0-1,1)R_пр, в висячем боку (1,3-1,4)R_пр.Приконтурная зона размером 0,8-1,5 м склонна к разрушению. Размеры зоны деформаций вмещающего рудного массива в лежачем боку (1,0-1,1)R_пр и висячем боку (1,1-1,2)R_пр, в кровле (1,1-1,2)R_пр. Стабилизации смещений вмещающего рыхлого и плотного рудного массива не зафиксировано.

Рассмотрено формирование естественного напряженно-деформированного состояния в массиве, сложенном различными средами, и изменение его вследствие проведения горной выработки. Задача решена математическим моделированием, основанным на методе конечных элементов. При моделировании было рассмотрено шесть схем с различными углами падения пород.

The methodology of determination of strength and deformation properties of ores is described. Tabular and graphical results of the conducted studies of ore characteristics of the Yakovlevskoye deposit are presented. The conclusion about the nature of ore fracture under uniaxial compression is made.