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The authors study the ground surface displacement in the area of Zhezkazgan copper ore field now subjected to extraction of ore reserves from rib pillars. The high-precision leveling procedure using digital leveling instrumentation and invar leveling staffs is proposed for the application in arrangement of a geodynamic test site at the settlements of Zhezkazgan and Lermontovo. The steel control survey points are firmly connected with rock mass by means of grouting. The observation results made it possible to detect and evaluate the ground surface displacements.

The presented procedure of slope stability analysis for open pits is based on the comprehensive studies into physical/mechanical properties and structural tectonics of pit wall rock mass with regard to jointing. The procedure is applied to find determine structural weakening and rock quality in Koktaszhal Open Pit Copper Mine in Kazakhstan.

The software and hardware tools for the instrumental estimation and control of the geomechanical state of engineering facilities are presented. A description of the proposed technique for measuring radial and longitudinal displacements of check borehole contour is given. A research methodology and interpretation of experimental data with analysis and monitoring of the stress-strain state of engineering facilities are proposed. The results of testing the developed software and hardware in the conditions of industrial enterprises are presented.

Using numerical modeling of rock mass stress–strain state to estimate and predict stability of structural elements of a mining system in combination with the in situ observation data on deformation of rocks in sidewalls, roofs and floors of underground excavations, the authors perform geomechanical analysis of overcutting scenarios in top-down mining in Internatsionalny Mine, ALROSA. Various overcutting flow sheets are considered, and the optimal sequence of overcutting towards higher stability of stopes is determined.

The article addresses the issues of geomechanical monitoring in underground mineral mining. A brief review covers existing software and hardware for estimation of stress state and properties of rocks and the results of in situ trial of an integrated tool set. The authors offer the geomechanical monitoring structure using a package of instrumental, visual and numerical methods for the assessment of mechanical condition and its alteration in rocks and in structural components of mines. Thereupon, the geomechanical state control system have been developed and introduced in a number of operating mines. For the stability assessment of structural elements in mines and for the decision-making on mining safety, the rock mass limit state criteria are defined.

The authors present the results of underground excavation lining examination aimed at detecting inhomogeneities in the lining (reinforcement metal, voids, weakening) and recommend on selecting the lining sites to be optimal for measurement hole drilling based on field observations.

Based on numerical modeling of stress-strain state of rocks and the in situ deformation monitoring of rocks mass surrounding underground excavations, the authors determine stability criteria for mine structural elements in terms of the Aikhal Mine where mining has been transferred under the worked-out open pit bottom. Using the determined criteria, the stress-strain state and subsidence of the crown pillar are assessed, considering current stage of the water table in the open pit. The article gives predictive estimate of the change in the stress-strain state and subsidence of the crown pillar upon the water level raising.

The researchers have obtained parametric criteria for geomechanical assessment of excavations stability based on numerical modeling of the closing rock mass stress-strain state and using the in situ observations. The authors present the predictive estimate of stability of stopes in the bottom-up slice mining in the Internatsionalnaya kimberlite mine.

The authors propose a procedure for estimating stresses, load bearing capacity and remaining life of lining in long-term operated underground tunnels using the analytical calculations based on solving the plane elastic problem on stress-strain state of a non-circular variable-thickness ring restraining a hole in a linearly deformed medium, and by the in situ measurement data.

The prototype of a new-developed program-instrumentation system provides automated measurement and processing of data on stresses in a rock mass by employing the parallel-hole method. The respective instrumentation and the procedure for execution of tests on stress evaluation within a rock mass are also briefed on. Recorder software provides the prompt control of the entire process with visualized parameters, thus contributing to the proper decision-making with account for experimental conditions and expediency to go on with downhole tests.

The trials of the automated stress measurement equipment have revealed the necessity to upgrade its component represented by the borehole strainmeter. Application of the digital microprocessing methods for signal measurement and conversion has allowed elimination of negative impacts and enhanced efficiency and reliability of stress?strain control in rocks.

The paper analyzes geomechanical conditions of slicing method application to extract a vertical ore body in terms of Internatsionalnaya kimberlite pipe. The authors assess stability of stopes at principal stages of horizon mining.

Based on the numerical modeling results, the authors have revealed the features of stress state in the vicinity of development and stope workings in the course of the upward slice chamber-and-pillar mining under the open pit bottom in terms of the mine “Aikhal”. The optimal layout of access entries and their mining sequence in a layer are substantiated.

It is proposed to construct long-term strength and creep relations for metals on the basis of the Coulomb-Mohr criterion. The creep equations and the long-term strength criterion for plane stress are analyzed in detail. Results of long-term strength calculations are compared with data of experiments with metallic materials. It is established that theoretical and experimental results are in satisfactory agreement.

A method is proposed for calculating the rock strength criterion by the results of sample tests under uniaxial compression and tension, as well as hydrostatic compression. The method makes it possible to simplify considerably the procedure of determining the rock strength parameters and improves the existing State Standard.

An analysis is performed for the distribution of stresses in the elements of slicing system in mining the “Internatsionalnaya” kimberlite pipe. The parameters and conditions of carrying out the stoping operations in experimental-industrial block by ascending slices are substantiated.

An analysis is performed for the stress state of edges and bottom of the “Aikhal/” open-pit mine. The influence exerted by the ratio of vertical and horizontal components of the initial stress-field on the results of numerical modeling of mining-technical situation in ceasing the open mining of kimberlite pipe is considered.

Changes in the temperature field and boundary displacements in the measurement borehole are investigated on the basis of a solution of the quasi-static problem of thermoelasticity. An experimental regime that ensures minimum error in the determination of stresses is established.

Use has been made of a deformation method proposed by the Mining Institute, Siberian Division, Russian Academy of Sciences as a component in the monitoring system for the state of stress and strain in the Sayan-Shushen HES dam during the working period; it is based on measuring the deformations of the shape and walls of galleries in the dam [1-3]. Those galleries have been equipped with standard reference testers: four-component rosettes for measuring the deformation of the walls (measurement baseline l = 1 m) and ones for measuring the displacements in the prof ile (l =2 .2-3.5 m). The means of measurement were provided by silica rods used with dial gauges and micrometers. The errors of measurement did not exceed 10-20 µm. Here we report observations on the processes in the part where the concrete has opened up on the upstream face between the 344-359 m levels (Fig. 1). Figure 2 shows the increments in the displacements in the arch and cantilever directions if parts of the longitudinal galleries (levels 344 and 359 m) during 1993-7. Those increments at the middle and end of the second column (positions 2-2 and 2-3 at a certain distance from the deconsolidation zone) indicate that the data agree well for both directions in all the reservoir filling and draining cycles. On the other hand, in the measurement areas near that zone (points 1-4 and 2-1), there were changes in the mode of deformation in the concrete, which show prominent residual effects that indicated that the zone was advancing towards the downstream face. The annual increase in the infiltration in that zone also indicates that the zone was extending. Figure 2 reveals clearly the effects of the filling cycles and the repairs done in 1996: in the cantilever direction at the 344 m level, the increments increase sharply and imply stretching in the first column and at the start of the second one, with some slight reduction in the stretching at the end of the second one (point 2-3, level 344 m). The splitting in the concrete causes the stresses to shift, the main feature being an increase in the stretching near the leading edges of the cracks, with an increase in compression at the water face (Table 1). As the infiltration was increasing, the directors of the Sayan-Shushen HES decided on repairs to that zone, which were carried out by the Soletansh firm at the maximal levels in 1996, which involved injecting tars through holes drilled in the concrete. Figure 3 shows the stress increments in a key section near the deconsolidation zone in 1996, while Fig. 4 shows those in 1995 and 1997. All the Fig. 3 data have been obtained at the maximum water level on the upstream side. The changes in the stress increments are due to the repairs. The extensive injection in the first stage and the other repairs have produced considerable changes in the increments in the cantilever direction at levels 332-359 m near the cracking zone. In the second stage, the injections were performed more cautiously, and the increments in the tensile stresses in the cantilever direction were somewhat less than those in the first stage. The stress increments in this key section on reservoir filling in 1995-1997 indicated that there was compression in the arch direction at the end of the first column and start of the second one in 1997 relative to 1995, which was increased at the levels of 344 and 359 m; and the stretching in the cantilever direction was reduced at the 344 and 359 m levels but was increased at the end of the first column and start of the second one at the 310 m level. The zone where the increments go over to compression at the 359 m level had been displaced from the downstream face to the central region. Table 1 gives the stress increments at the downstream face (section 33) during the seven-year observation cycle. During 1992-6, there was an annual increase in the compressive stresses, while the anomalously large increase found in 1996 may have been due to more pronounced air temperature changes in the anchor support region by comparison with previous cycles. Nevertheless, even if one incorporates the thermal stresses, which are estimated to constitute additional compressive ones of 18-20 kgf/cm 2 , and also if one allows for the rise in upstream level of 35 m (by comparison with 40 m in previous years), one concludes that the threat to the downstream face in 1996 was considerably greater than those in previous cycles. In subsequent years (1997-8), there were reductions in the increments in the maximal compressive stresses.

Calculation results obtained on the basis of Coulomb-Mohr and Mises-Schleicher theories are compared with experimental data for rock samples.

1. The positive results of grouting cracks in concrete of the upstream face of the Sayano-Shushenskoe dam are not limited to suppression of seepage between elevations 344 and 359 m. Substantial compression of concrete of the first column and beyond the limits of this zone at higher and lower elevations was obtained without advance of the cracks into the depths of the dam during injection of the grout under high pressures, which also prevented seepage. 2. It is necessary to consider well-founded the requirement of limiting additional opening of cracks during grouting to 1.5 mm. 3. When making calculations for estimating the effect of grouting on the SSS of the dam, one should not proceed from the average pressure in the crack being grouted, since its value is difficult to establish. It can tentatively be considered a rigid inserts over the entire front of the crack with a thickness on the upstream face of 1.75–2 mm and converging to 0 in the zone of joint I–II.

Experimental evaluation of stresses in a block of rocks is normally doneby indirect methods. The reliability of stress estimates obtained by mechanical procedures based on measuring strains and displacements is determined primarily by correspondence between the elastic constants of the medium assumed for calculations and their true values. The characteristics measured on samples usually differ from those obtained in situ. The discrepancy in the modulus of elasticity is frequently significant so that constants determined in situ are preferable for calculations. In the method of parallel holes [1-3] this problem has been solved by simple means which made it possible to completely "ground in the nature" this method of stress measurement.