Modified pseudo-dynamic bearing capacity of strip footing on rock masses

In this paper, the seismic bearing capacity of a strip footing sitting on rock masses has been investigated following the upper bound theorem of limit analysis. The generalized tangential technique is used to obtain the equivalent Mohr-Coulomb parameters of the modified Hoek-Brown criterion. Considering the damping char-acteristics of the site as well as the dynamic characteristics of the seismic waves, the modified pseudo-dynamic (MPD) method is applied to evaluate the seismic effects. A parametric study is conducted, which shows that the seismic acceleration coefficient, the geological strength index, the material constant of the intact rock, and the normalized frequency all have a significant effect on the seismic bearing capacity. The MPD results are also compared with other methods, including the conventional pseudo-dynamic (CPD) method, spectral pseudo -dynamic method (SPD), and pseudo-static (PS) method. A high degree of agreement can be observed between the MPD results and the CPD results as the normalized frequency increases. When the normalized frequency equals (0.5 + n)pi, the values of the bearing capacity factor obtained by using the MPD method and the SPD method will hit their local minima, while the CPD and PS methods will overestimate the bearing capacity factor to a large extent.

Automated summary

The seismic bearing capacity of a strip footing on rock masses is investigated using the upper bound theorem of limit analysis in this paper. The equivalent Mohr-Coulomb parameters of the modified Hoek-Brown criterion are obtained using the generalized tangential technique. The seismic effects are evaluated using the modified pseudo-dynamic (MPD) method, taking into account the damping characteristics of the site and the dynamic characteristics of the seismic waves. A parametric study is conducted, and the results show that the seismic acceleration coefficient, geological strength index, material constant of the intact rock, and normalized frequency all have a significant impact on the seismic bearing capacity.