The Research For Surrounding Rock Stability Of An Underground Cavern With Water Seal

In this paper, just taking the underground cavern in Yunan as an example, we researched and discussed the area geology, engineering geology and hydro-geological conditions, rock cavern surrounding rock quality and level and so on. Without considering groundwater, the characteristics of natural stress field in rock mass were analyzed and simulated by using Phase software. Through the numerical simulation analysis of stress and displacement characteristics in caverns. the main conclusions are summarized as follows:1, According to a comprehensive analysis such as stable terrain fluctuation, completed mountain without collapse, landslides and debris flow, there is little influence on the stability of the surrounding rock cavern. Per preliminary analysis, it is suitable to build the underground cavern.2, According to the methods of the BQ score, Q system and T score, the relationship between the quality and depth of surrounding rocks in the study area was obtained. The quality level of the gentle granite is the 2nd lever. The total score of T is more than 65 and the strength of surrounding rock is over 4. The fine grained granite in the field area is stable, but we couldn’t rule out the possibility of reinforcement in partial area.3, The surrounding rock stress redistribution was adjusted after excavating the cavern without any supporting conditions. It contains several parts. First, compared with the initial maximum principal stress release surrounding a cavern, it drops about 0.2-2.5MPa. Second, both two sides and edge angle of the caverns, the stress concentration is obvious, but there is no maximum principal tensile stress area in the whole cavern. Meanwhile, the surrounding rock deformation performance trend is more obvious. The rock and soil move to the direction of excavating. Deformation influence range is 1.5 times higher. Therefore, surrounding rock is easier to be damaged at the top, which may cause the collapse. The Compression shear failure may occur in the side, which may lead to the rock burst.All in all,based on the existing engineering methods,it has guiding significance for the next phase of work that we research, analyze and evaluate the stability of the surrounding rock in the underground cavern.