The Influence Of Underground Cavern On Side Slope Of Open-Pit Mine

Stability analysis of side slope is an important research field of disaster prevention and reduction in engineering. There are many factors to affect the stability of side slope, among these factors, the underground vacant area is the exterior factor, and the slip of side slope and the subsidence of the surface of side slope are the two destructive forms that can be caused by it. According to the existent relation of underground vacant area and side slope, it also can be divided into two cases:the first one, the underground vacant area has been existed before the slope is excavated, such as the underground mined-out area under the slope of the open-pit mine; the second one, the slope has been existed before the underground vacant area is excavated, such as the excavation of tunnel in mountainous areas.The paper is based on Gongchangling open-pit mine Hejia panel in Liaoyang. The rock mass in Hejia panel fractured, the joint is developmental, the condition of rock mass is bad, therefore the preliminary determination can be gained that the existence of an empty area will be a great threat to the slope stability of mining area. Basing on the actual monitoring about the empty area, through establishing numerical model, the slope stability of open pit with empty area is analyzed. By comparison, it can be gained the impact of the empty area on the slope. Finally, the safe roof of the empty area is analyzed in two conditions of same span and different span.The results show that the existence of empty area did not landslide in the gob, but it largely dropped the safety factor of slope. According to the principal stress distribution of each measure point of slope theoretical potential failure surface and the principle of Mohr circle, it can conclude that most areas of the rock in the theoretical potential failure surface near the empty area has been damaged. Meanwhile, the existence of empty area also increases obviously the slide displacement and enlarges the distribution of plastic zone. On the basis of Strength Reduction Method, the safety factor of slide is significantly smaller. If the span of empty area is certain, the thicker the roof, the smaller the maximum tension stress; if the thickness of the roof is certain, the greater the span, the greater the maximum tension stress.