Research On Risk Assessment Of Water Inrush In Panlong Lead Zinc Mine,Guangxi

Karst mine water inrush is a major hydrogeological problem affecting normally mined ore bodies,but the effect of surface water level uplift on water inrush in mines has rarely been reported.Taking the Panlong Pb-Zn mine in Guangxi as the research object,this thesis investigated the impact of the rising water level of the Qianjiang River on the risk of water inrush in the mine area.Based on the analysis of geological and hydrogeological profiles,this thesis investigated the hydraulic linkage of water gushing-Qianjiang River water-meteoric water by using cross-correlation function and Mann-Kendall mutation analysis;investigated the risk of water inrush in the mine area with the elevated water level of the Qianjiang River using improved AHP,and determined the water inrush risk level in the mine area using matter-element extension method;finally,zoned the vulnerability of water inrush in the Daling mine section based on the vulnerability index method.The relevant conclusions are as follows:（1）After the impoundment of Datengxia Reservoir from 2019 to 2020,the water level of Qianjiang River raised 10 m～20 m,the area of sewer drainage landing funnel in the mine area increased about 1 km²,and the water level in the center of the funnel lowered about 35.21 m,forming the eastern Qianjiang River fixed water backflow recharge boundary,the western lateral runoff recharge boundary,the southern Lower Devonian Yujiang Formation（D₁y）and the northern Ertang Formation（D₁e）locally constituting a relative water boundary.（2）The mine area water-filling water source is mainly meteoric water and Qianjiang River water;the same period between the water inflow and meteoric water inter-annual lag of 2～3 months,and the inter-month lag of about a week;the water inflow sequence shows a sudden change point in June 2019,followed by a sudden increase in water inflow during the river flood,and the correlation between precipitation before and after reservoir storage-water burst and Qianjiang River water-water burst weakened and enhanced respectively.Therefore,the degree of recharge of the Qianjiang River water to the groundwater of the mine pit after 2019might be greater than that of meteoric water.（3）Horizontally,the main inflow sources are the Qianjiang River on the east side of the mining area,the karst aquifer groundwater on the west and the north side;in the vertical direction,the pit water burst mainly concentrates in-70 m and-320 m in the middle section,which,the water-filled intensity of-70 m～-120 m in the middle section is affected by karst medium development conditions;however,due to the deep part of the mine interlayer dissolution fissure is more developed,the mining pit concentrated water burst depth has been transfering from-70 m～-120 m to-320m～-440 m.（4）Based on the gray risk calculation and the improved AHP method,which generally indicates that the elevation of Qianjiang River water level will increase the risk of water inrush in the mine area to some extent,otherwise the comparative analysis based on matter element extension method and fuzzy mathematics method showed that the comprehensive water inrush risk level in the mine area is II,and the current risk level is still within the controllable range.（5）The results of the water inrush vulnerability zone in the mine area show that:the vulnerable and more vulnerable zones are mainly located in the west and southwest sides of the mine area,accounting for 40.47%;the transition zone is located in the northwest,west and east parts of the mine area,accounting for 25.81%;the safer and relatively safe zones are located in the middle,northwest and south parts of the mine area,accounting for 33.71%.Combined with the information of mine water inrush,it is considered that the water inrush risk assessment have certain practical reference significance.