This shift is due to both improved safety standards and technology as well a move away from underground mines towards surface mining and controversial mountaintop-removal mining.

这种数据上的提高在于安全标准的提升和技术的进步，同时，地表开采和富有争议性的削山开采也使得地下开采也逐渐走到地上。

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The roof shape optimization is one of the important means to control the ground pressure. A long strip of exposed roof surface shape can improve productivity of the stope and ensure mining safety.

优化采场顶板暴露面积形状是控制地压的重要手段之一，采用长条形顶板暴露面，能提高采场生产能力和保证回采的安全性。

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It is the most common way to remain coal safety pillar for protecting surface buildings from mining damage.

留设保护煤柱是防止建筑物受采动损坏的最常用方法。

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