沈北大桥立井煤田,系新生界下第三系煤系。煤系顶板为含动植物化石较多的泥岩,其上覆盖第四系冲积层。煤系底板为杂色泥岩、凝灰岩、安山岩和玄武岩,其下为震旦纪矽质灰岩。煤层顶、底板岩层的主要物理力学性能见表1。这些岩层的成岩条件 Shenbei Bridge shaft coal, Department of Neozoic Tertiary coal system. The coal-bearing roof is mudstone with more flora and fauna, covering the Quaternary alluvium. Coal-bed floor is variegated mudstone, tuff, andesite and basalt, which is Sinian Si limestone. The main physical and mechanical properties of coal seam roof and floor rock are shown in Table 1. Diagenetic conditions of these formations