Abstract: By consulting domestic seismic study on tunnel entrance, large scaled shaking table model tests of the entrance on homogeneous upward slope, slope with weak intercalation and strengthened slope were carried out in laboratory. General conclusions were obtained through analyzing the failure modes of the upward slopes. Under the earthquake, tension cracks appeared first at the shoulder of the slope, with the excitation acceleration increasing, soil at the shoulder started to dump and collapse; when introducing the weak intercalation, the soil at the toe of slope was squeezed broken firstly, tension cracks of the surface appeared at the weak interlayer positions, overlying soil sliding along the weak interlayer and leads to large-scaled soil collapse; the strengthened slope remained stable under the action of the force, only caused partial soil failure; minor axial cracks appeared at top. By analyzing the tunnel structure failure, the test results show that the fracture distribution on the A and B linings of tunnel portal are more complex than that on C and D linings; the total length can be taken as the earthquake affect length, which corresponds to 40m at the actual project. Affected by the weak interlayer, the fracture of the lining parts crossed the weak interlayer are more complex than others; the slope reinforcement can improve the stress state of both the slope and portal structure. These conclusions can be for reference in design and construction of tunnel under earth quake.

Key words: entrance of tunnel, upward slope, linings, fracture characteristics, shaking table tests