Study On Surrounding Rock Pressure Characteristics Of Underground Station With Extra-large Section And Small Spacing

With the development of urban rail transport, the number of domestic undergroundstation with extra-large section increase gradually. Since the time is short, the theoreticalresearch of underground station with extra-large section is far behind the engineeringpractice. There has not been a unified understanding of the distribution rule ofsurrounding rock pressure of the station with extra-large section.Sometimes, to meet theengineering structure and the functional performance and also affected by the specialgeological envionment, the underground station with extra-large section and smallspacing has to be built. Its surrounding rock pressure characteristics has become morecomplex. But its design and construction have to be solve the problem. So the study onsurrounding rock pressure characteristics of underground station with extra-large sectionand small spacing is of more important theoretical significance and engineeringpractical value.Based on the analysis of the engineering geological conditions of Chongqing railtransit line6,the first period Lijia station and previous research, and through the theoryanalysis and numerical simulation to the station in the excavation process, it researchedthe distribution rule of the surrounding rock pressure and the characteristics of pressurearch. The main contents of the research are as follow:①It analyzed and summarized the calculation method of surrounding rockpressure,when the station is excavating. According to this calculation method, it got thevertical and horizontal pressure of the sation at different depths when the first hole andfollowing hole are respectively excavating.②According to the pressure arch research and the characteristics of Lijia station, itgot the judgment standard of the pressure arch boundary when the first hole andfollowing hole are respectively excavating.③Analyzing the stress of the station and according to the judgment standard ofthe pressure arch boundary, it got the influence of the buried depth, surrounding rockmechanics parameters and construction methods to the pressure arch boundary, whenthe first hole and following hole are respectively excavating.④According to the project characteristics of Lijia station, it established2D finiteelement numerical mode and analyzed the change of surrounding rock pressure indifferent construction stage. It also respectively got the surrounding rock pressure of different depth and spacing by changing the depth and spacing.⑤Selecting the station typical section, it compared the theoretical analysis valuewith numerical simulation value of surrounding rock pressure.It also analyzed thereason for the difference.