In order to ensure safety and top coal caving in time, the measures of pre-blasting or water pre-infusion to weaken top coal should be adopted.
为确保安全和顶煤及时垮落，应实施预爆破或预注水弱化顶煤措施。
In order to ensure safety and top coal caving in time, the measures of pre-blasting or water pre-infusion to weaken top coal should be adopted.
为确保安全和顶煤及时垮落，应实施预爆破或预注水弱化顶煤措施。
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