Comparing Eurocode 8-5 and AASHTO methods for earth pressure analysis against centrifuge tests, finite elements, and the Generalized Coefficients of Earth Pressure

Abstract

This paper presents an exhaustive comparison of the earth pressure methods included in EN1998-5:2004 (use of Mononobe-Okabe method, M-O), prEN1998-5:2021 and AASHTO (M-O with half peak ground acceleration) standards, against contemporary centrifuge tests, finite elements, and the method proposed by the first author in 2019. The latter is a continuum mechanics approach for deriving earth pressure coefficients for any soil state between the “at-rest” state and the active or passive state, applicable to cohesive-frictional soils and both horizontal and vertical pseudo-static conditions. The same method also provides analytical expressions for the calculation of the required wall movement for the mobilization of the active (or passive) failure state, as well as for the mobilized shear strength values of soil. The comparison includes among others, centrifuge test results from two different studies, and results from 157 finite element models from two different programs. All experimental, numerical, and analytical results show that the EN19985-5:2004 method gives conservative to excessively conservative active earth pressure values, AASHTO’s approach fairly good behavior, while prEN1998-5:2021 excessively conservative values. For the passive state, all methods included in the above-mentioned standards, return unreliable and unconservative results. In contrast, the results obtained by the proposed method show a remarkable agreement with the respective ones obtained both by the finite element method and the various centrifuge tests. Also, it is shown that a pseudo-static earth retention analysis, can be replaced by a respective static analysis, just substituting the (c', φ') values of soil of the original problem with the mobilized ones.

Designing embedded retaining walls relying on the Generalized Coefficient of Earth Pressure and the elastic beam theory

“…The wall is 3-meter tall and it is pushed towards a soil with 𝑐'=0 kPa, 𝜑'=25 ο and 𝛾=20 kN/m 3 ; the system is subjected to a horizontal sesimic excitation with 𝑎 ℎ =0.2 (the vertical pseudo-static coefficient, 𝑎 𝑣 , is zero). The numerical resuts have been obtained using Rocscience's RS2; avoiding repeatition, the full desciption of the finite element procedure followed is described in Pantelidis and Christodoulou [8]. As shown in Figure 12, there is an excellent agreement between the analytical results of the proposed method and the respective numerical ones, at least upto the depth near the lower end of the wall; near the lower end, the numerical passive earth pressures appears bloated.…”

“…It is important to be mentioned that both the proposed earth pressure coefficients and the expression for 𝛥𝑥 𝑚𝑎𝑥 , are accompanied by an exhaustive validation procedure and comparison with the earth pressure methods included in EN1998-5:2004 [5], prEN1998-5:2022 [6] and AASHTO [7] standards (see [8]). The comparison includes among others, centrifuge test results from two different studies, and results from 157 finite element models from two different programs.…”

Shaft resistance capacity of axially loaded piles in cohesive-frictional soils under static or pseudo-static conditions based on ground parameters

“…An exhaustive validation of Pantelidis' (2019) continuum mechanics approach against contemporary centrifuge tests and finite elements can be found in Pantelidis and Christodoulou (2022); the same paper also presents an in-depth evaluation of the earth pressure methods included in EN1998-5:2004 (use of Mononobe-Okabe method; Mononobe and Matsuo, 1929;Okabe, 1926), prEN1998-5:2021 and AASHTO (use of the M-O method with half peak ground acceleration; AASHTO American Association of State Highway and Transportation Officials, 2010).…”