Numerical Estimation of Seismic Earth Pressure on Walls of Basements Underlain by Bedrock

Dynamic increment of earth pressure is one of the primary parameters in the seismic design of underground basement structures. Both analytical solution and empirical methods developed for rigid walls have been used to estimate the seismic earth pressure. The equations do not account for the important influence of the flexibility ratio (F), which represent the relative stiffness between the structure and the surrounding soil. Most of the equations also do not account for the aspect ratio (L/H) of the basement. A comprehensive suite of dynamic numerical analyses was performed using a range of basement configurations underlain by bedrock and soil profiles to calculate the build-up of seismic pressure on the basement walls. It is demonstrated that both F and L/H have important influences on the seismic earth pressure. Relatively stiff basements with high L/H values are exposed to larger increment of seismic earth pressure compared with flexible structures with low L/H values. Through regression analysis, an empirical procedure to estimate the seismic earth pressure that accounts for both F and L/H are proposed. The residual analysis highlights that the proposed procedure provides reliable predictions and does not introduce bias across all cases considered in this study.