A. A. Baryakh

Sinkhole formation mechanism

A mathematical model of a growing cavern is used to describe possible scenarios of sinkholes in the karstic areas. The authors present formation criteria for ground surface sinkholes and underground caverns, and estimate their sizes.

Water-tight stratum rupture under large-scale mining. Part II

The physical simulation of water-tight stratum failure using one-layer and multi-layered platebeams has revealed some patterns of formation of long main fissures in the plate-beams under bending, depending on thickness and amount of the layers. The experimental results become a parametric basis for mathematical modeling of real-time failure of a water-tight stratum.

Evaluating the residual life of salt pillars

ConclusionsThus, the completed studies have made it possible to develop a technology and methodology, based on the compensation method, for measuring the load on the edges of inter-chamber pillars. An experimental-theoretical method has also been proposed for estimating the residual life of such pillars in excavated sections of potassium mines.The results of full-scale measurements established that the edge regions of interchamber pillars located near the boundary of a cave-in (region of chamber 103 in our investigation) are in the supercritical state. For a subsidence rate of 1.5 mm/day at the surface, the residual life of such pillars is estimated to be 7–8 months.The zone loaded by bearing pressure from the caved-in rock is shifted toward the interior of the goal (regiona of chamber 120). The load factor of the pillars exceeds the allowable value [C]=0.4 specified by standards for “rigid” interchamber pillars in the mines of the Verknekamsk Potassium Salt Deposit, which accounts for their “compliant” regime of deformation. Thus, to reduce the strains of the water-protective stratum and prevent water above the deposit from entering the mine, the region of chamber 120 must be filled.

EFFECT OF OIL FIELD DEVELOPMENT ON THE GEODYNAMIC STATE OF THE INTERIOR OF THE EARTH

ConclusionsThus, the geomechanical analysis performed suggests that hydrodynamic impact of oil field development on dislocational break is a potential cause of technogenic seismic phenomena. For the discussed variants of calculation the magnitude of these events is rather insignificant. Unquestionably, the data obtained are preliminary because account has not been taken of the whole diversity of technological variants under conditions of complex deep structure of the rock mass. Possibly, in these cases the consequences of changes in the geodynamic situation may be more significant. Further studies should be continued in the direction of refinement of the geophysical model, for which it is necessary to obtain more comprehensive and precise information about the change in the dynamics of subterranean water under the influence of oil field development as well as about the structure of the rock mass, natural stress field, technological parameters of exploitation of the field, and so on. This will make it possible to raise the adequacy of the geomechanical model and to get more reliable prognostic assessments of the geodynamic consequences of oil field development.

Formation of technogenic disturbances above the worked space in potassium mines

ConclusionThe computational apparatus that we have developed for mathematical modeling makes it possible to assess variation in the stress-strain state of a salt mass during its working and to determine the conditions under which zones of subvertical jointing are formed in layers of the waterproof stratum on the basis of criteria of fracture mechanics.The seismoacoustic monitoring that we performed confirmed the validity of geomechanical forecasting calculations. The evolution of such an automated system for the recording of seismic events will make it possible to carry out continuous remote monitoring of technogenic failure in the rocks of a waterproof stratum or potentially dangerous sections of potassium-mine fields from the results of mathematical modeling. Incorporation of monitoring units into a flood-protection system for potassium mines opens prospects for conversion to a qualitatively new level of geomechanical support for the safety of mining operations.