Mining effects of grouted-rock composite of grout curtains based on optical fiber and microseismic monitoring systems:A case study of the Maoping lead-zinc mine in Northeast Yunnan,China
Grout curtain is a regional groundwater control project serving the whole life cycle of the mine.Its effective service can greatly reduce the risk of water inrush in deep stopes and en-sure the safe and efficient exploitation of deep resources.Maoping lead-zinc mine is located in the southwest edge of Yangtze block,with developed geological structure,complex hydrogeo-logical condition,and high risk of water inrush during deep mining.Based on the concept of ac-tive prevention and control of water inrush hazard,the regional grout curtain reconstruction project is designed and implemented in the north and south of eastern mining area.Based on the optical fiber monitoring system of the curtain body and the microseismic monitoring system of the mining area,this paper analyzes the stress evolution process and damage fracture mecha-nism of the grouted-rock composite of grout curtain under the coupling effects of the excavation disturbance stress and the high seepage pressure difference inside and outside the curtain.Based on the monitoring results of optical fiber and microseismic system,the instabili-ty model and criterion of the grouted-rock composite of grout curtain are established.The opti-cal fiber monitoring results show that the stability of the grouted-rock composite within 0-140 m of the northern curtain is good,and it is basically not disturbed by mining activities.Howev-er,the 140-206 m range is affected by obvious shear stress,which is the result of mining dis-turbance.The variation of strain difference and settlement of the southern curtain is small,the settlement rate decreases gradually with the increase of depth,and is less disturbed by the mining engineering.The microseismic monitoring results show that the intensity and frequency of microseismic events in the eastern monitoring area are significantly higher than those in the western monitoring area,and the microseismic events in the northeast of the north curtain and in the west of the south curtain are locally banded,which are the weak parts of the curtain body and may induce potential seepage damage.The investigation results can provide a refer-ence for the evaluation of long-term water blocking effectiveness of grout curtain and the im-plementation of deep water control project.
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