A method for calculating the required amount of air for gas ventilation of the internal combustion engine of railway tunnels has been developed. This method takes into account such provisions as the direction of air movement to the direction of train movement, train speed and the number of trains simultaneously in the tunnel. Cases such as a train standing motionless with the engine running, train movement towards and against the direction of airflow, and cases of multiple trains in the tunnel are analyzed. For all variants, calculation equations of the required air quantity and recommended train speed that can ensure the concentration of pollutants in the tunnel below the MAC (maximum permissible concentration) are proposed.

The main factors determining the peculiarities of accident-free operation of railway tunnels under windless climate conditions are considered. It is shown that ice formation caused by a combination of two unfavorable phenomena: relatively low air temperature in the tunnel and high watering of the tunnel is especially dangerous. The paper presents the results of the experimental studies indicating that the gas composition of the tunnel air is determined not only by the harmful gaseous impurities emitted by the carriers but also by methane, carbon dioxide, hydrogen sulfide and radon coming from the surrounding rocks and water. The mechanism of radon impact on tunnel personnel has been studied and a large-scale description of its possible impact on air quality in the tunnel has been given. Many regions of the Russian Federation, including those where the longest railway tunnels of Russia are located: Baikalskiy and Severo-Muiskiy, can be classified as radon hazardous. Creation of rational ventilation conditions influencing not only the radiation situation but also the thermodynamic characteristics of the air should be considered as a fundamental means of achieving the required air quality in the tunnels. In order to increase the stability of ventilation conditions the possibility of using different regulating devices has been studied. The maximum influence on the air flow is exerted by the installation of a ventilation door, which allows to change the air inflow by 70% of the initial indicator. The principles of creation of the favorable temperature conditions in the railway tunnels, which is one of the effective means of ice formation prevention, have been implemented and tested on site.

Production studies using a specially developed methodology have shown that the pillar system of potash development at the Starobinsky deposit results in the release of combustible gases into the existing mine workings. The main component of these gases is methane, heavy hydrocarbons are emitted in insignificant amounts. Under normal conditions the absolute gas emission at the mine sites is insignificant. In the total gas balance of the sites, the main part (up to 98%) is gas emission from the mined-out space.

Maintaining preparatory workings in good condition is one of the conditions determining the normal development of cleaning works. ...

The stability of mine workings depends to a large extent on the shape of their cross-section and the corresponding outline of the support. However, this well-known position is often not taken into account, as a result of which the load-bearing capacity of the support is not fully utilized.

A four-hinged brace is a statically defined geometrically variable system with one degree of freedom. In ground structures, geometrically variable systems are almost never used due to their instability. Therefore, the construction mechanics does not provide a specific methodology for their calculation.

Tekeli lead-zinc ore deposit is a complex powerful steeply dipping lenticular deposit. The rocks of the hanging and lying sides are represented by strongly fractured, collapse-prone coal-clay shales with interlayers of dolomitized limestone and other sedimentary rocks. The ores are stronger and more stable than the host rocks and are represented by sulfides disseminated in coal-clay shales, quartzites and coal-quartz shales, as well as pyrite ores ...

The nature of manifestations of mining pressure largely depends on the size of the cross-section of mine workings. As is known, in the same mining and geological conditions, maintenance of two-track workings is much more expensive than single-track workings. In this regard, in some basins of the Soviet Union in difficult mining and geological conditions prefer to pass two smaller cross-sectional workings instead of one large one. For example, in the Moscow sub-basin panel drifts should be double-tracked according to the conditions of mining technology, because almost the entire length consists of loading points. In the reverse order of mining the mine field, it is considered more favorable to sink panel drifts as single-track drifts with subsequent expansion to double-track drifts by the time of longwall face approach. The total costs are lower than when sinking two-track drifts at once. In the latter case, the cost of maintaining the workings increases sharply ...

In the current seven-year Tenteksky and Churubay-Nurinsky coal districts are the main areas of construction of new mines in the Karaganda basin. Conditions of maintenance of horizontal and inclined mine workings at the mines under construction are as diverse as physical and mechanical properties of rocks in which these workings are sinking. Maintenance of rolling mine workings of Tenteksky district does not present great difficulties, as sinking is carried out mainly in strong stable rocks. The most difficult conditions for maintenance of mine workings of Karadzharo-Shakhansky section of Churubai-Nura district, especially at ventilation horizons. Fasteners installed here (solid wooden, metal, prefabricated reinforced concrete, etc.) due to high all-round pressure are deformed and must be replaced. Most of the mine workings were reinforced several times during the construction period. Reinforcement works require large expenditures of labor, time and money.

In the process of drilling of mine shafts the washing fluid is contaminated by the drilled rock, which leads to deterioration of its quality, reduction of drilling performance, and sometimes to complications and accidents. In order to restore the mud quality it is necessary to continuously clean it from drillable rock. Among various mechanisms and devices used for cleaning of flushing muds, the most widespread are vibrating sieves.

Cleaning the bottom hole from the drilled rock and bringing it to the surface when drilling shafts and boreholes is one of the main functions performed by the flushing fluid. In the process of drilling the flushing fluid is contaminated with drilled rock and its percentage in the fluid increases. The high content of drilled rock in the flushing fluid deteriorates its quality, causes collapse of the borehole walls (due to deterioration of claying of its walls) and poses a risk of seizing the drilling tool during the termination of flushing. Besides, the increase in the percentage of rock content in the flushing solution requires more energy for flushing, increases the wear of drilling equipment parts, and significantly reduces the drilling speed.