Feasibility of artificial surcharge application for reduction of TBM entrance shaft depth

Commonly in mechanized tunneling projects, TBM entrance shafts are used for the excavation start. The existence of incompetent geotechnical conditions especially the presence of water inflow makes difficulty in construction of shafts and increases the cost and time of construction. The application of artificial surcharge may be appropriate solution for reduction of required depth of shafts. as a case study, in order to depth reduction of west TBM entrance shaft of Tabriz metro line 2, the practicability of artificial surcharge usage with soil-cement material was investigated. The proposed method besides constructional easiness decreases the shaft construction time and cost considerably. For this purpose a 3D finite element model is used employing the ABAQUS software (Ver. 6.10). Based on obtained results and considering stability analysis, surface settlements and probable inclination of TBM, the artificial surcharge can be successfully used for the reduction of required shaft depth. Also based on field monitoring data successful tunnel excavation and passing of TBM shield from prepared area is reported

کلیدواژه ها:

Mechanized tunneling ، TBM entrance shaft ، artificial surcharge ، FEM