Abstract
In order to grasp the mechanical behavior of shallow tunnel excavation in the intersection, three dimensional trap door tests have been developed and performed. Dry sand (Hamaoka sand) has been used for ground material. With changing overburden pressures, the width of trap door and the intersection angle between tunnels, the variation of vertical earth pressure acting on trap doors, the distribution of earth pressure and the settlement of ground surface have been measured. Based on the experimental results, it has been confirmed that the variation of earth pressure with moving the branch trap door has been strongly affected by the initial overburden earth pressure and the intersection angle. Then, three dimensional earth pressure theory has been suggested using Terzaghi's earth pressure theory and its application has been discussed in the experimental results.
