In situ measurements verify the above by observing the confined water intruding up into the coal floor,the protective strata,before mining.This paper considers the secondary stress as the conditi...

• 底板的原位应力测试发现承压水在采前出现了向上入侵的现象，二次应力给导升的发展提供了条件，递进导升是突水机理之一。