Upper bound solution to seismic active earth pressure of submerged backfill subjected to partial drainage

In waterfront geotechnical engineering,seismic and drainage conditions must be considered in the design of retaining structures.This paper proposes a general analytical method to evaluate the seismic active earth pressure on a retaining wall with backfill subjected to partial steady seepage flow under seismic conditions.The method comprises the following steps:i)determination of the total head,ii)upper bound solution of seismic active earth thrust,and iii)deduction for the earth pressure distribution.The determination of total head h(x,z)relies on the Fourier series expansions,and the expressions of the seismic active earth thrust and pressure are derived by using the upper bound theorem.Parametric studies reveal that insufficient drainage and earthquakes are crucial factors that cause unfavorable earth pressure.The numerical results confirm the validity of the total head distribution.Comparisons indicate that the proposed method is consistent with other relevant existing methods in terms of predicting seismic active earth pressure.The method can be applied to the seismic design of waterfront retaining walls.

Estimation of active earth pressure based on pseudo-dynamic approach and discretization technique

A method combining the pseudo-dynamic approach and discretization technique is carried out for computing the active earth pressure.Instead of using a presupposed failure mechanism,discretization technique is introduced to generate the potential failure surface,which is applicable to the case that soil strength parameters have spatial variability.For the purpose of analyzing the effect of earthquake,pseudo-dynamic approach is adopted to introduce the seismic forces,which can take into account the dynamic properties of seismic acceleration.A new type of micro-element is used to calculate the rate of work of external forces and the rate of internal energy dissipation.The analytical expression of seismic active earth pressure coefficient is deduced in the light of upper bound theorem and the corresponding upper bound solutions are obtained through numerical optimization.The method is validated by comparing the results of this paper with those reported in literatures.The parametric analysis is finally presented to further expound the effect of diverse parameters on active earth pressure under non-uniform soil.

Pseudo-dynamic active earth pressure behind retaining wall for cohesive soil backfill

A formula was derived for the computation of seismic active earth pressure behind retaining wall using pseudo-dynamic method.This formula considered the actual dynamic effect with variation of time and propagation of shear and primary wave velocities through the soil backfills.The influence of tension crack in the top portion of the backfill under seismic loading was investigated.The effects of wall friction angle,soil friction angle,horizontal and vertical seismic coefficients on the seismic active force were also explored.The parametric study shows that the total seismic active force increases as horizontal seismic coefficient increases,while it decreases with the increase in vertical seismic coefficient,internal friction angle and unit cohesion.The seismic active force calculated by the proposed method is larger than that calculated by previous theory.