STUDY ON HYDRAULIC PROPERTIES OF SOFT ROCKS IN THE SHANGHAIMIAO COAL MINING REGION IN THE NORTHWESTERN EDGE OF ERDOS BASIN IN CHINA

The Shanghaimiao mine is located in the southwest part of the Inner Mongolian Autonomous Region, and in the northwestern edge of the Erdos basin, which is one of the most important energy coal mine bases in China. The coal mine in this area is characterized by the large burial depth and complicated exploitation conditions. The laboratory tests were carried out to investigate the permeability, swelling, collapse and softening coefficients by utilizing the core samples attained during the geotechnical investigation drilling. The test results show that the permeability and softening properties of coarse sandstone, fine sandstone, siltstone, silty mudstone tend to decrease. The collapse coefficient of coarse sandstone is clearly lower, and that of fine sandstone is slighter higher than others',but those of three sets of silty mudstone are rather scattered. The free swelling coefficients of medium coarse sandstone, fine sandstone and siltstone tend to decline respectively, but those of three sets of silty mudstone are rather scattered too. The mineral ingredients of rock samples include quartz, potash feldspar, plagioclase and clay minerals, but the content of clay minerals are not stable. By comparing the test results, the hydraulic properties seem to not be irrelevant to the mineral contents, which still needs further research. These research findings are of great significance to the latter coal exploitation.