A closed-form logarithmic spiral method for seismic passive earth pressure in anisotropic sand

The shear strength of soils is always anisotropic due to the compaction and deposition history. A closed-form logarithmic spiral method combined with an anisotropic failure criterion is proposed to estimate the seismic passive earth pressure coefficient and failure surface of anisotropic sand. The seismic condition is implemented by the pseudo-static approach. The results obtained by the proposed method are validated by methods in the literature and by the finite element method based on a proposed anisotropic Drucker–Prager model. The comparisons show that the method is effective and efficient. In addition, the seismic passive earth pressure coefficients considering various backfill slopes and various soil-wall frictions are presented for reference in engineering design.