Mine inonoations

The paper describes the types of inundations affecting underground mining operations together with their safety, operational, and stability implications. A critical analysis has highlighted three major causes of inundations. These have been classified as event controlled, accidental or spontaneous. The event controlled inundations are associated with the development of fracture zones around a longwall working and followed by main and periodic roof falls in caved mine workings, particularly in coal mines. An approximate theory to predict the event of main and periodic roof falls in the goaf behind the long wall face is given. These types of inundations have been illustrated with several case histories.     

Estimate of Stress-Strain State of Rocks in the Area of Drilling Kola Ultradeep Well

The values of horizontal tectonic stresses are estimated up to depth of 11 500 m by the measurement of velocities of longitudinal and transverse waves in rock samples extracted from various depths when drilling Kola Ultradeep Well.     

Control of the coal-rock boundary by elastic vibrations

Conclusions The marked difference between the rates of damping of longitudinal mechanical vibrations in metal rods brought into contact with specimens of coals and rocks gives grounds for assuming that this phenomenon may be utilized for remote discrimination between coals and rocks. This makes it possible to develop a special sensor for automatic control of the direction of movement of heading and extraction machines exactly along the boundary of the coal seam, i.e., along the boundary between the coal and rock. Donetsk Polytechnical Institute. Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 5, pp. 124–128, September–October, 1975.