Bai, Y. and Hu, Y., 2018. Overlying strata movement of below protective seam. In: Liu, Z.L. and Mi, C. (eds.), Advances in Sustainable Port and Ocean Engineering. Journal of Coastal Research, Special Issue No. 83, pp. 193–198. Coconut Creek (Florida), ISSN 0749-0208.
The characteristic and intensity of the overlying strata movement during the below protective seam mining play an important role to relieve the effect of the protected coal seam. Taking Wangjialing No. 2 mine as the experimental mine, with the method of deep base point, the settlement regularity of the immediate roof, basic roof and hard rock stratum are studied. At the same time, the mechanical model of basic roof is analyzed. Results show that: The immediate roof is falling down layer by layer, lower part of immediate roof is the first to cave, and its upper caving lags behind the lower caving. The immediate roof will fall behind the working face; The settlement pattern of main key stratum is similar to that of the basic roof, but its amount and severity are less than that of the lower rock. With no abscission layer and no fracture for key layer delamination, the form is overall coordination of settlement; The movement of basic roof can be divided into three stages, and the settlement value increases as the measuring point become further to the coal face; the further the distance of the face to roof, the smaller the severity will be.