ガス突出による噴出炭を主とした “きれつ” の顕微鏡的研究 (続)
1973 年 89 巻 1024 号 p. 381-386
詳細
1973 年 89 巻 1024 号 p. 381-386
In the present paper microscopic studies of fissures in coals picked from coal seams are described. The results obtained are as follows:
1) The fissures in coals thrown out by outbursts which occurred recently in 3 or 4 coal mines including Simizusawa Coal Mine, show the same appearance as shown in the previous paper.
2) In the samples of coals taken from the vicinity of folds, foults and volcanic dikes underground, the fissures are not found, but in the samples crushed by air hammer, the fissures are found. These fissures are similar to the fissures in coals thrown out by outbursts. From this fact, it is presumed that these coals have been kept under the tectonic stress.
3) When a normal volume of cuttings is produced by boring in the working face, the fissures are not found in the cuttings, but when the several times of cuttings are produced, the fissures are found. Therefore, the measurement of the volume cuttings of by boring in a coal seam may be used, as a method of the practical prediction of outbursts.
4) In the coal fractured by adding an external force such as compression, tension, bending or shearing stress, the fissures are not found. But after the above fractured coal is crushed by air hammer, the fissures similar to those in coal thrown out by outbursts are found in coal crushed by air hammer.
