Mitigation of Seismic Accelerations by Soft Materials Embedded in the Ground

Seismically induced accelerations are greatly affected by the transmission through soil layers. The stiffness and damping of the material beneath a structure can therefore influence the seismic loads experienced in the structure. Recently, there has been interest in the use of very low shear stiffness materials in subsoil beneath structures in order to act as a filter to seismic motions, but there is significant skepticism as to its practicability. In this chapter, some notable contributions are discussed, and some work showing the physical modelling and numerical modelling of a soft-material scheme that showed initial promise is presented. This is seen to be readily modelled as a simple mass-spring system, which could be applied to other similar cases. Future challenges include development of a suitable material for the purpose, and reliably proving static stability.