矿床开采的年下降深度。开采速度的大小直接关系到矿山的生产能力和年采矿量。影响开采速度的因素主要有：采矿方法、矿床的可采面积（矿体平均水平厚度与沿走向总长度的乘积）、矿体倾角大小、同时回采的中段数目、开采的机械化程度和生产管理水平等。在运用公式确定矿山生产能力时，其中年下降深度是重要参数。
西方森林面积的快速增长似乎同其他各地的森林开采速度一样不可阻挡。
The growth of Western forests seems almost as unstoppable as deforestation elsewhere.
能够作出在一定时间内不同开采速度条件下的地表移动变形曲线。
Some graphs of surface movement and distortion can be shown also when working face is advanced with different mining speed in certain time.
除此之外，似乎技术进步只是加快了石油的开采速度并没有增加油井覆盖的石油量。
Besides, many technological improvements seem to have simply speeded up the extraction of oil, rather than increasing the share of each reservoir that can be recovered.
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