Forensic Evaluation of Compacted Soils using RAMCODES

Abstract

Unexpected failure of compacted soils was explained using design curves of the Rational Methodology for Compacted Geomaterial’s Density and Strength Analysis (RAMCODES). Forensic geotechnical evaluation, applied to a compacted soil used at a construction site, demonstrated that the bearing capacity of the soil was influenced by the water content and the dry unit weight. At the construction site, the only criterion used for quality control of the compacted soil was the minimum compaction percentage; the maximum dry unit weight (achieved using the standard Proctor test) was used when the soil was compacted with light equipment, and the maximum dry unit weight (achieved using the modified Proctor test) was used when it was compacted with heavy equipment. After changing water content conditions, the soil compacted with heavy equipment and the soil compacted with light equipment exhibited changes in bearing capacity; the soil compacted with light equipment showed a failure, whereas the soil compacted with heavy equipment did not. The causes of failure were evaluated from samples of soil analyzed in the laboratory; analysis was performed using design curves obtained through a factorial experimental design. Our analysis revealed that the criterion of minimum compaction percentage was not adequate to determine the actual mechanical performance of the soil. We sought to determine why the soil compacted with light equipment did not satisfy the bearing capacity expected after compaction, and what other actions should performed at a construction site to avoid failure of soils compacted with light equipment.

Implementación del espectro de curvas de diseño ramcodes de suelos no saturados de subrasantes en el diseño de pavimentos flexibles

“…In addition, the values of standard deviation (Zr), combined standard error (S0), initial serviceability index (PSI0) and final serviceability index (PSIt) were taken from the recommendations of [14]. The structural number (SN) of the pavement was obtained by means of (6). As it can be seen in this equation, it is not possible to solve it by clearing the value of SN; therefore, an iterative process must be followed by means of some algorithm of approximation of the zeros.…”

“…Oyola-Guzmán and Oyola-Morales [6] in 2018 used the design curves of the RAMCODES methodology to explain the cause of failure of a compacted soil, whose compaction quality control was only verified by the minimum percentage of compaction (95% of the maximum dry unit weight of a standard proctor or a modified proctor). The design curves were obtained from the results of the laboratory tests of a silt-clayey sand where its water content and dry unit weight were varied, and the mechanical response of the soil was measured based on the CBR test.…”