Strengthen safety risk control of open-pit mine slope to prevent collapse accidents

(3) Conduct professional analysis and evaluation of slope stability. Open-pit mining enterprises shall, in accordance with the relevant provisions of the Safety Regulations for Metal and non-metal Mines, conduct slope stability analysis at least once every 5 years and form the Slope Stability Analysis and Evaluation Report. The slope stability analysis and evaluation work should be carried out by the units that have the relevant qualification of geological disaster prevention or have the ability of open-pit slope stability analysis and evaluation. The initial slope stability analysis and evaluation should be completed after the completion of the mine construction project and before the acceptance of the safety facilities.

(4) Carry out "expert consultation" on slope safety with greater risks. Emergency management departments should regularly organize "expert consultation" type safety inspection for open-pit mine slopes with greater risks. For slopes with a height of more than 30 meters and slope angles greater than 30 degrees, the county (city, district) emergency Management Bureau will organize an "expert consultation" every year. On this basis, the municipal emergency management bureau will carry out an "expert consultation" once a year on the final slope with the current height of more than 50 meters and the slope Angle of more than 42 degrees or the current height of more than 100 meters and the slope Angle of more than 30 degrees; The provincial Emergency Management Department organizes an "expert consultation" every year for the final slope of production mines with a current height of more than 200 meters. The "expert consultation" shall evaluate the stability of the slope and the effectiveness of the measures already taken according to the geological report of the mine, the site survey and the slope risk control situation of the enterprise, and form the inspection list of the expert consultation of the open-pit mine slope safety (see Annex 2).

Third, strengthen engineering measures to improve the level of slope risk control

(1) Strengthening slope safety protection. For the overall stable final slope, transportation road slope and other non-working slope, mining enterprises should take engineering and technical measures such as hanging net, setting up safety platform, anchoring and spraying to prevent local collapse and falling blocks. If the slope is found to be unstable or extremely unstable after analysis and evaluation, the design unit shall determine the treatment plan or protective measures. Unstable slope and extremely unstable slope before the completion of governance, stability or basic stability, the dangerous area should take temporary measures such as stopping production and evacuating people, hard isolation, and strictly prohibit personnel from entering.

(2) Standardize the construction of slope engineering. The slope Angle and platform width of open-pit mine must conform to or be better than the design. Controlled blasting or mechanical excavation should be used in the adjacent slope operation to reduce the damage to the slope and maintain the safe slope Angle of the steps. Overdigging the slope bottom is strictly prohibited. To standardize the construction of slope drainage facilities, slope drainage facilities must meet or better than the design requirements; Finally, each step of the slope should be provided with a drain in principle, through which the rainwater can be discharged from the slope.

(3) Precise slope control measures. In the process of mine production and construction, if the engineering geology or hydrogeology type of the mine is found to be inconsistent with the type determined by the original geological report, and is inferior to the original geological report, the slope parameters and risk control measures should be adjusted immediately in accordance with the preliminary geological type. At the same time, it is necessary to timely entrust relevant units to supplement geological exploration, adjust geological types, and revise the "Safety Facilities Design"

Fourth, strengthen safety monitoring, improve slope risk early warning ability

(1) Actively promote slope safety monitoring. The open-pit mine shall entrust the design unit to carry out the overall design of the slope monitoring program according to the final slope boundary, different periods and different mining requirements, and according to the slope safety monitoring grade determined by the Slope Stability Analysis and Evaluation Report in each zone, and clarify the monitoring content and monitoring program by region and stage. When the final slope is not formed, temporary monitoring points should be set up on the stope slope. When the final slope is formed, long-term monitoring points are set up on the final slope. The safety monitoring content shall be implemented in accordance with the relevant provisions of the Technical Specification for Safety Monitoring of High and Steep Slopes in Metal and non-metal open-pit Mines (AQ/T 2063-2018).

(2) Comprehensively carry out online monitoring of slope displacement with large risks. For the final slope whose safety monitoring grade is one or two, the surface displacement must be monitored online. For the final slope with a safety monitoring grade of one, internal displacement online monitoring should also be set up. Considering the variability of geological conditions and calculation error of slope monitoring grade, if the final slope height is more than 200 meters (including 200 meters), it is necessary to establish online displacement monitoring in accordance with the requirements of safety monitoring grade 1. The final slope with a height of 100-200 meters and the final slope with a height of 30-100 meters and complex geological conditions should at least establish an online displacement monitoring system in accordance with the requirements of safety monitoring level 2. Encourage open pit mine to use slope radar to carry out slope surface displacement safety monitoring, improve slope safety monitoring capability; The on-line monitoring system of slope surface displacement can not be built if the radar monitoring of slope meets the requirements of the standard.