Behaviour of soilbags subjected to monotonic and cyclic vertical loading

Soilbags have been successfully used in the reinforcement of building foundations that can function as the base isolation. A series of unconfined compression tests under monotonic and cyclic loading were conducted to investigate the static bearing capacity and the dynamic deformation behaviour of stacked soilbags. The results of monotonic loading tests demonstrate that the ultimate compressive strength and the tangent compression modulus of soilbags tend to relatively stable values of around 0.7 MPa and 6.73 MPa, respectively, when the number of layers exceeds three. Under cyclic loading, the accumulated vertical strain of stacked soilbags increases nonlinearly under the application of cyclic loading, reducing with each loading cycle and even reaching a relatively stable state where the vertical strain is primarily elastic, which can be described with an empirical formula with respect to the static vertical stress, the cyclic load ratio and the number of loading cycles. The resilient moduli of stacked soilbags change slightly during cyclic loading period, and increase with the increasing static vertical stress and the decreasing cyclic load ratio. The outcomes of this study demonstrate the feasibility of soilbags as the base isolation as they have prominent bearing capacity and stable deformation behaviour under cyclic loading.