Use of Kruskal-Wallis and Mann-Whitney statistical tests to evaluate geotextile-reinforced soil systems

ABSTRACT

The main objective of this research was to evaluate the influence of the type of reinforcement geotextile, soil, geosynthetic reinforcement insertion position and compaction energy on the mechanical behavior of geotextile-reinforced soils. This evaluation was based on the results of the Unconfined Compressive Strength (UCS) and Direct Shear tests. In order to evaluate the influence of these factors on the mechanical behavior, non-parametric tests were used, according to the number of samples of each factor. The Kruskal-Wallis tests were applied for the factors “soil” and “type of geotextile” and the Mann-Whitney tests for the factors “position of insertion of the geotextile” and “compaction energy”. In general, the results did not show significant differences in UCS of reinforced soils compared to unreinforced ones. For the behavior of different reinforced soils, the difference between the results was dependent on the reinforcement mobilization. Regarding the different geotextiles applied and the different location positions of these elements, it was noted that such factors did not exert statistically significant effects on the UCS parameter. When the different compaction energies were analyzed, it was observed that the increase in this energy led to an increase in the contact of the geosynthetic with the soil, increasing the interface friction forces and generating greater increases in UCS. When analyzing the results referring to the direct shear strength tests, it was noticed that the changes in compaction energy, soil and type of geotextile did not present a statistically significant difference on the parameter and that the insertion of different geotextiles in the different soils studied did not promote complete interaction between the materials, providing the deficiency of interface friction.

Keywords
Non-parametric tests; Soil-geotextile; Mechanical Behavior