Experimental Assessment of Soil Consolidation properties Representing Geotechnical Irregularities in Earth-fill Dam for Static and Seismic Non-linear Analysis

Abstract

The static and seismic stability of earth-fill dam embankments is significantly affected by geotechnical anomalies, including heterogeneous soil properties.

This paper provides an experimental assessment of soil consolidation and geotechnical variability in earth-fil dams. Laboratory tests were conducted on samples taken from Al-Moshanaf dam that had slope stability failure on its upstream face and located in southern Syria an area well known for widespread of expansive clay soils. In addition to old boreholes, field and laboratory tests performed in 2018 that confirms anomalies due to clay procurement from different quarries, new specimens confirm irregularities in Dam that was designed and executed as a homogenous earth-fill dam. Lithological section confirms existing different geotechnical properties in dam body. Experimental study aims to obtain moisture content, unit weight, grain size distribution, Atterberg limits, specific gravity and consolidation parameters, to analyze those results then to investigate their relationship with slope stability failure of the dam.

Comparison of old and new tests indicate variability in geotechnical properties inside the dam body, unit weight of old and new specimens reveals an average increase of 6%, also a progressive material degradation due to seepage-induced clay migration at upstream face, resulting in different soil settlement behavior. Consolidation tests, following ASTM D2435 and ASTM D4546, reveal high differential swelling percentages between adjacent zones that reaches 90%, and compression index variations, including seepage-exposed zones, that may lead to potential stress concentrations and instability at critical zones interfaces. The comparative analysis of consolidation methods highlights nonlinear responses of embankment soils to cyclic wetting, laboratory tests show that the maximum swelling-to-compression differential ratio of adjacent zones is 10% for first cycle of loading, whereas it rises to 67% in the second loading cycle the reason that cracks may develop,  emphasizing the need for refined predictive stability models in dam rehabilitation.

By quantifying consolidation trends and geotechnical irregularities, this paper seeks to bridge gaps in geotechnical assessment methodologies. The findings provide foundational data to support future non-linear numerical modeling efforts, helping refine static and seismic design strategies for earth-fill dam rehabilitation and stability evaluation