Large-scale shaking table tests on the liquefaction and deformation responses of an ultra-deep overburden

Abstract To study the liquefaction problem of the dam foundation of an ultra-deep overburden in the strong earthquake area, a large-scale shaking table model test is carried out based on a 500 m rockfill dam project on an ultra-deep overburden. A laminar shear box was used to simulate the seismic response of the free field dam foundation under earthquake action. Under the action of 0.1–0.8g bidirectional ground motion, the changes in excess pore-water pressure in different positions of the ultra-deep overburden are analyzed, and the liquefaction characteristics of the ultra-deep overburden dam foundation are discussed. The results show that the excess pore-water pressure decreases first and then increases from the bottom to the top of the overburden when the PGA reaches 0.48g. In addition, the excess pore-water pressure is small in the clay layer and begins to increase in the surface near the ground. With the increase of the PGA, the excess pore-water pressure increases at each position, and the maximum value is located at the bottom of the overburden. The excess pore-water pressure ratio is always small below the clay layer but increases above the clay layer. When the PGA reaches 0.48g, the excess pore-water pressure ratio exceeds 0.8, and the soil liquefies. With the increase of the PGA, from the bottom to the top of the overburden, the maximum dynamic soil pressure in the horizontal direction increases first, then decreases, and then increases, while the vertical direction is just the opposite.