UDEC simulation results show that the porosity of overburdenrock fissure field in goaf and its curve is saddle-shaped.
UDEC模拟结果表明，采空区覆岩裂隙区域孔隙率曲线呈鞍状分布。
2
It is important to master movement rules of overburdenrock layers to control roof rationally in special production and geological conditions.
在工作面特定的生产技术和地质条件下，掌握工作面上覆岩层的运动规律，对合理控制顶板非常重要。
3
The essential elements are source rock, reservoir rock, seal rock and overburdenrock, and the processes include trap formation and the generation-migration-accumulation of petroleum.