緩傾斜層における地表沈下特性

Abstract

In most coal mines in the northern district of Kyushu, precalculation of surface subsidence by the method developed in Germany was made for the purpose of investigating some possible way to minimize damages.On the other hand, surface subsidence had been measured in those mines for years, and even horizontal displacement had been measured in a few mines. However since the results of measurement had not been made open to the public, the actual state of subsidence in Japanese coal mines was not fully clarified.Recently the authors obtained fortunately the results of measurement of subsidence and horizontal displacement carried out in sixteen mines. From these data, the features of surface subsidence caused by mining inclined coal seams were made clear in comparison with those caused by mining horizontal seams.seams. The main features of them may be that the maximum subsidence is greater on the dip side than on the rise side and the former appears between the point just above the center of mined area and the intersection of the surface with the normal to the coal seam drawn from the center of mined area, and that the horizontal displacement is far greater on the dip side than on the rise side but the point of no horizontal displacement is found near the point just above the center of mined area.The mechanism of the subsidence which shows such the features as described above was investigated by the gelatine model experiments and it was suggested that the phenomena of subsidence consisted in separation of the coal measures above the mined space followed by sagging and shifting of them towards the mined space.