Study On Stability Of Surrounding Rock Of Subway Station In Steep Rock With Weak Intercalation

The geological condition of Chongqing subway ring line Lianhuacun station is complex, and it is a steeply layered rock mass and comes with part of weak intercalation, besides due to large section, so it is very important to study on the stability of tunnel surrounding rock. This paper mainly studies on the stability of tunnel surrounding rock by theoretical analysis, field monitoring and numerical simulation. The main work and research results are as follows:①Based on the previous research results, this paper analyses the destruction types and the destruction mechanism of layered rock mass, and summarizes 5 typical destruction types in steep rock; and this paper analyses tunnel excavation methods and their advantages and disadvantages in large section; and this paper summarizes the factors which influence the surrounding rock stability with weak intercalation.②According to the engineering geological conditions, this paper builds theirs two-dimensional finite element modle of three bench method and double side drift method, and analyses the surrounding rock displacement, stress and plastic zone. The analysis results show that using three bench method can be more scientific to ensure safety and efficient of tunnel construction, and this is proved in the actual construction.③Based on the establishment of three-dimensional model, this paper analyses the surrounding rock displacement, stress and tunnel time and space effect during the process of excavation from three views of the deformation characteristics, the stress characteristics and the distribution characteristics of plastic zone of surrounding rock. The analysis results show that the surrounding rock displacement, stress and plastic zone shows an obvious asymmetry, and the relative displacement of sandy mudstone-sandstone happen.④Through scientificly and rationaly designing six different conditions, this paper analyses that the weak intercalation is how to influence on the stability of surrounding rock by numerical simulation, when the weak intercalation is distributed different position. The analysis results show that the distribution position of weak intercalation is very important to the surrounding rock displacement of different parts, this is a very meaningful for similar engineering design.