It is of great practical significance to carry out quantitative risk assessment of landslide disaster to protect people 's lives and property safety and maintain the sustainable development of social economy. The delineation of landslide disaster range is the key link of landslide risk evaluation in open-pit mine. This study took the open-pit mine in a block of Tar coalfield in Pakistan as the research background, and constructed a framework for landslide risk evaluation in open-pit mines. Based on the numerical simulation method of large deformation of landslide, the disaster range of landslide in open-pit mine was delineated. The stability of stope slope was analyzed based on rigid body limit equilibrium method. The probability of landslide instability was calculated based on Monte Carlo method. And the comprehensive fuzzy evaluation model was established to calculate the total risk value of landslide. The results showed that : through numerical simulation and empirical formula calculation, the landslide disaster range was accurately delineated, and the comprehensive vulnerability of the disaster bearing body was determined to be medium vulnerability ; the annual probability of landslide instability under natural conditions was 0.003, which belongs to moderate risk. The annual probability of landslide instability under rainstorm conditions was 0.024, which was highly dangerous ; the annual probability of landslide instability under seismic conditions was 0.018, which was highly dangerous. Under natural conditions, the total risk value of landslide was 114686.4 rmb, and the annual mortality rate of population was 0.0255 people / year. The total risk value of landslide under rainstorm condition was 11707570 rmb, and the annual mortality rate of population was 0.18375 people / year. The total risk value of landslide under earthquake condition was 43007400 rmb, and the annual mortality rate of population was 0.135 person / year, which was an unacceptable risk. The economic loss was a small geological disaster risk under natural conditions, and it was a medium-sized geological disaster risk under both rainstorm and earthquake conditions. Therefore, landslide prevention and control and management measures such as slope deformation monitoring were proposed to ensure the safety of personnel and property in open-pit mines.

To effectively manage the stability of in-pit dumps with an underlying weak layer, a new plan for the treatment of a staged floor during the life of a mine was proposed in this study. Based on direct shear test results, the shear properties of contact surfaces between the weak layer, dumped spoil, and mudstone were determined. Taking the Baiyinhua No.1 Open-pit Mine as an example, a direct shear test of the contact surface between the spoil and the mudstone determined its cohesion to be 25.78 kPa, and the internal friction angle was 17.58°. The cohesion of the contact surface between the spoil and the weak layer was 7.50 kPa, and the internal friction angle was 9.72°. Different floor treatment rates were subsequently determined based on discontinuous structural surface and limit equilibrium theories. The in-pit dump plan was divided into stages based on a 10-year mine plan; a “safety reserve coefficient” was used as the conditional factor to calculate the minimum floor treatment rate. The results of a numerical simulation analysis of the slope stability of the untreated and treated inner dumps showed good agreement with results obtained by the limit equilibrium method. The position and shape of the sliding surface were also found to be similar, indicating the validity of the established numerical simulation model and the reliability of the calculated results. Based on field application and economic effect analysis, it was found that this proposed method can minimize the floor treatment rate effectively while maintaining a sufficient factor of safety. The direct economic benefit of this method was approximately 1,694,259 dollars at the Baiyinhua No.1 Coal Mine. This method is of great significance to safe and efficient production, and can be widely applied.