Determination of the temporary tensile strength of subcoal clays of the Moscow Basin

Abstract

The conditions for developing heavily flooded brown coal deposits in the Moscow Basin, located in unstable rocks, are determined by the features of their geological and hydrogeological structure. For deep-lying deposits in the southern and western wings of the basin, the main feature is the presence of a subcoal aquifer with a water pressure of up to 90 m. These pressure waters are the cause of water breakthroughs from the soil of mine workings. At the same time, clay strata lying in the soil of mine workings and protecting them from water breakthroughs from the subcoal aquifer are of decisive importance for the safe conduct of preparatory and cleaning mining operations. The thickness of the subcoal clay layer and its strength determine the need and scale of drainage measures during deposit development. All other things being equal, the need to reduce the pressure of subcoal waters and the magnitude of this reduction will depend on the minimum strength of clays. Facts show that under the action of hydrostatic pressure, the soil of mines workings will experience tension when bending. Therefore, to correctly select the scheme and volume of drainage works, it is necessary to know the ultimate tensile strength of clays, their temporary resistance. The temporary tensile strength is usually the smallest compared to the temporary resistance to shear (shear) and compression. Thus, the value of the temporary tensile strength of clays is the main calculation parameter for deciding on the need to drain mine fields. Meanwhile, the tensile strength of clays has hardly been studied. In numerous articles devoted to the development and drainage of brown coal deposits in the Moscow Basin, this issue has hardly been covered.