Xitiesan Mining Ground Subsidence Control Factors And Surface Stability Analysis

Xitie mountain lead zinc ore is located in Qinghai province, through many years exploring, there exists a 3.2 million empty area. Along the direction of exploring, earth surface collapse has happened in many parts. It must influence the mine production safety if let it be.According to the investigation on the scene and collection data, The author have done some work as following: dividing land collapse area and surrounding rock to five engineering geology rock set according to the rock engineering geology characteristic; analyzing land collapse controlling elements, then predicting earth surface stability, at last putting forward measures.In accordance with mine area rock physical and mechanical properties, dividing land collapse and its surrounding rock to five groups: Mb, Sc, the mineral set, the volcano rock set and St.The formation of land collapse is related to the huge empty area, geological structure, Strata and rock physical and mechanical properties and weather, hydrology.The main reason resulted in the land collapse is the existence of empty area, the shape and scale of empty area affects the stability of the overlying rock directly, which decide whether the land collapse will happen and its scale, According to the scale of empty area and which whether lead to land collapse, this article divides it to four groups: the empty area which is isolated and far away the producing area, the top and bottom level segment is connected and closed to producing area, the top and bottom level segment is connected and located in the same ore body which have formed huge empty area, the empty area which is in 2492-3062m level segment, among them the last two empty area influence the land collapse greatly, which decide whether the land collapse will happen and its scale.The affection of The mineral area structure to the land collapse appears in faults broken the integrity of overlying rock of the empty area and lowered therock bearing capacity, The small scale plait within the green schist makes rock distort, and broken rock to pieces, So it reduces the rock's physical and mechanical properties obviously.Among the five engineering geology rock sets, the greatest influence on the land collapse is Sc, which is not only the layer the mine within it, but also which is the surrounding rock, among them carbon schist is broken, fissure well-development, low intensity and which will be soften and expansion if it contact with water. So it isn't stable as surrounding rock.The influence of weather, hydrology on land collapse is that water will heaven overlying rock load because of water gathering in rainy season or ice melting and the gathering water can penetrate underground to make carbon schist soaked in water which will lead to the rock soften, expand and low intensity. In addition, mine area weathering is intensity, so the earth surface forms a huge weather crust, which will low the rock intensity.On the base of clarifying the controlling elements of land collapse, this article predicts the rock development trend in 9-63# exploring line, and analyzes the law of earth surface in 0-9# exploring line, at last puts forward the prevention and treatment measures to the land collapse.