Stability Analysis Of Surrounding Rock During Large Surge Shaft Excavating Under Complex Geology

The surrounding rock stability during large surge shaft excavating under complex geology is one of the key considerations in hydropower engineering, due to its complex mechanical model and various influential factors. That how to deal with it is seriously connected with safety of excavation and future commercial operation. Generally speaking, in studying on surrounding rock stability, analyzing methods and mechanical models adopted determine the correct degrees of the result. Based on the large surge shaft engineering of Futang Hydropower Station, block theory and 3-D finite element method are used to analyze the stability of surrounding rock during the large surge shaft excavating under complex geology.1.Block theory and 3-D finite element method were used to analyze the stability of surrounding rock during the large surge shaft excavating after systematic analyzing characteristics of the surrounding rock.2.During the study with stereographic projection, cylindric free surface of circular surge shaft is simply converted to eight walls. This makes it possible to analyze the random blocks of surrounding rock with stereographic projection.3.With the block theory stereographic projection method, potential sliding blocks and their displacement modes are studied in the lower part of the surge shaft. Then the values of sliding force and the safety factor of stability of the potential key blocks are worked out.