Abstract:Calculation of residual subsidence amount in minedout area is a method for analyzing dangerous degrees in goaf quantitatively. The state of early coal forming goaf has been directly simulated by using FLAC3D, and the residual settlement of the old minedout area has been calculated. Taking chemical engineering project in Zaozhuang city of Shandong province as an example. Firstly, by using geophysical prospecting and drilling methods, depth, roof falling and broken condition of old goaf have been gained. Secondly, combining with parameters results of geological materials obtained from core test, FLAC3D simulation has been carried out, residual sbusidence amount under the action of gravity and residual subsidence amount after loading construction of old goaf have been calculated. Compared with traditional probability integral method, subsidence results are similar. It is showed that the calculation method is reliable. Finally the relationship between load stress and residual subsidence have been analyzed. It will provide scientific basis and references for stability evaluation and calculation of residual subsidence amount in old goaf.