| The slant to slow tilt or thin to medium thickness phosphate rock is a type of complex ore body in mining process.This type of ore is in the earlier period mineralization and ore body structure is quite compact.The thickness of the ore body is thin to medium thickness and the dip angle of more than 3/4 of the ore layer is less than 55 degrees,thus,only a few of these ore bodies are suitable for high strength mining.According to the characteristics of soft texture of phosphate rock,most of the phosphorus mines are exploited by room and pillar method,which has a positive effect on maintaining the stability of the stope.With the extraction of phosphate mineral resources,the equilibrium state of the stress of the primary rock is constantly broken,the area of the underground goaf is also expanding.Under the action of load and water,the pillar and the roof in the empty area are weathered,creep and gradually unstable.If it is not treated,on the one hand,it causes the waste of resources,on the other hand,it may induce collapse and the landslides in the empty area.In this paper,the old goaf of the Zhonghua Yunlong no rented phosphate rock is studied.In view of the specific existing conditions and physical mechanics characteristics of ore body and surrounding rock,conduct a survey of underground goaf and surface subsidence.Domino's dominoes,AHP,limit span theory,surface subsidence monitoring and FLAC3 D numerical simulation are used to analyze the stability of the mined out area and verified by each other.and a reasonable and effective treatment plan for goaf is put forward,.The main research contents are as follows:1.Collect the geological data and take a detailed geological survey of the mine.The statistical analysis of pillar and roof of goaf are carried out under the mine,and the status of surface subsidence and landslide is investigated.2.Study on the stability mechanism between the load,strength and the roof of the pillar.Analyse the safety factor of the local pillar in the goaf by using the Domino domino effect,and analyse roof stability with the theory of ultimate span of roof,thendetermining the safety status of pillar and roof;3.The analytic hierarchy process(AHP)is used to sort the factors affecting the stability of the goaf,and the order of the influence degree of each factor is determined.In combination with the actual situation of no rented phosphate rock,the stability level of the goaf is determined.The ground monitoring network is set up,the subsidence trend of the ground surface as well as the safety state of the goaf is analyzed with monitoring data;4.The goaf model is established by FLAC3 D,and the simulation analysis of the stability of the goaf is made,and verified with Domino domino effect,analytic hierarchy process and monitoring data.,so as to judge the safety state of goaf and provide reference for the management of it;5.Summarize the results of the previous analysis,the governance scheme is determined,and the management scheme is simulated to ensure the effectiveness of the governance scheme. |
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