Slope Stability Analysis Of Open-pit With Underground Mining

Based on the principles of rock engineering geomechanics, the rule about the movement of the covering rock is studied while the combined mining method is applied under the strip mine slope.The in-situ monitor is carried on during initial period mining; the obtained data is analyzed and the rule is summarized. Then the project which has been done is studied with the method of numerical simulation. Compared with the in-situ monitor data, the parameters of numerical simulation are revised continually and the rule of stress distribution is obtained. The future trend of development on the project is studied, aiming to instruct safe production effectively.The investigation on the joints and fractures has been done. The dip and inclination of the joints and fractures is measured by geological compass in the process of measuring by the detailed line. The statistical analyzed on each data is applied. The Schmidt projection of surface of equal density and the Schmidt projection of lines of equal density are made by the computer. The superiority jointing groups are determined and the direction of structural principal stress is got.In the part of monitor, the displacement and blasting vibration monitoring on the surface and the depth rock have been done. Through monitoring displacement of the surface and the depth rock, the movement rule of rock mass is summarized and it is determined that the influence scope, the influence angle and subsidence angle of the underground mining, and so on .It is done that analyzing the rule of its vibration weakening and evaluating the slope stability through monitoring blasting vibration which is produced by the strip mining. In the part of numerical simulation, the remove rule and the failure mechanism of rock slope are studied in the process of the underground mining.The research indicates that the synthesis mechanized mining has the various adverse effects on the stability of the rock mass above the underground mining area .Inside the rock slope above the area, the principal stress direction arises deflection, and the principal stress difference increases. The tensile stress occurs in the anticlinal axis parcel near the slope surface. The shearing stress on the weak plane increases and the stress concentrates in the comer of the slope. The rock-falling and fractured zones made the rock strength reducing and the horizontal displacements of the rock slope towards the underground mining area increase. The underground mining will urge the slope rock mass slip. The surface blasting has big influence on stability of the seriously weathered rock mass. It should be done that strictly controlling the explosive charge weight, blasting time delay interval and frequency; lightening the influence of underground mining on the slope stability and enhancing the slope stability through expansion of slope to get cross anticlinal structure and fills in promptly the crevasse to reduce rain corrosion in the future production.