Weakening top coal by using water pre-infusion is one effective method to solve this problem.
提高顶煤放出率是综放开采的一个重大课题，预注水弱化顶煤是解决这一问题的有效方法之一。
2
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。
3
While we have not seen dose-limiting toxicity at this level with the slower infusion (without pre-medication), we have seen headache in two patients, which is a moderate adverse effect.