Research on the Calculation Method of Ultimate Bearing Capacity of High and Steep Slope in Deep Waste Pit

Aiming at the ultimate bearing capacity of high and steep slope in deep waste pit, the calculation method of ultimate bearing capacity of high and steep slope in mine pit is deduced by using characteristic line method in combination with Hoek-Brown strength criterion and considering the action of pressure wall and composite beam anchored by anchor cable. In combination with engineering examples, the influence of slope α, rock mechanics parameters GSI, m₀ and active support force of anchor cable on ultimate bearing capacity of rock foundation of mine wall is analyzed. The research shows that: (1) The bearing capacity coefficient decreases linearly with the increase of slope. When the GSI is 45 and m₀ is 7, that is, when the rock mass of the pit wall is of poor quality limestone, the bearing capacity after anchoring is about 1.32-1.54 times of the bearing capacity before anchoring. Considering the combined beam action of anchor cable, it can be used as a safety reserve; (2) With the quality of rock mass getting better, the ultimate bearing capacity coefficient of foundation increases more and more greatly. When slope α is 60° and GSI is 85, bearing capacity coefficient is 1.28 when pit wall is good rock mass; when GSI is 45 and pit wall is poor rock mass, bearing capacity coefficient is 0.23; the former is about 6 times of the latter, indicating that the quality index of rock mass has a great influence on bearing capacity.