The use of grading entropy in assessing granular soil hydraulic conductivity

Hydraulic conductivity is an important geotechnical engineering property as it is linked to the performance of many geo-structures. This study used a recently compiled granular soil database (CG/KSAT/7/1278) to evaluate the best fit probability density functions for important parameters in the database. The Loglogistic function was found to be the best-fit probability density function for the parameters from CG/KSAT/7/1278 investigated in this paper. The grading entropy parameters (un-normalised) were used to develop a chart that highlights trends from the effect of changes of the gradation parameters on the estimated soil permeability

Measurement of field hydraulic conductivity for a Quito soil

In Quito, Ecuador, landslides present a significant threat to communities settled on hillsides and ravine slopes, and geotechnical data is needed to assess slope stability. Saturated hydraulic conductivity is a key input parameter for mechanistic modelling of rainfall infiltration and the pore water pressure conditions that can trigger landslides. This paper presents field data of in-situ saturated hydraulic conductivity by working with communities to conduct field measurements on the cemented volcanoclastic soils found in Quito. The new field data is then compared with predictions from recently established geodatabases of hydraulic conductivity obtained from laboratory tests on fine-grained and granular soil

Hydraulic conductivity of fine-grained soils subjected to freeze-thaw cycles

This paper presents laboratory data from tests on four fine-grained soils: reconstituted Kaolinite, destructured Bothkennar clay, reconstituted Bothkennar clay, and reconstituted Gault clay. The soil samples were conditioned in an oedometer cell while being subjected to varying numbers of freezing and thawing cycles. The influence of freeze-thaw cycles on key soil parameters, including the hydraulic conductivity, Atterberg limits, compression and swelling index was studied. The experimental results were then compared with the analysis of a previously published database of hydraulic conductivity measurements on fine-grained soils called FG/KSAT-1358. The paper demonstrates that while multiple cycles of freezing and thawing affect some of the studied soil parameters, such as the Atterberg limits and the compression characteristics, the effects on the hydraulic conductivity transformation model parameters, linking the water content ratio to hydraulic conductivity are less apparent. The results are useful for geotechnical and pavement engineers when making assessments of freeze-thaw effects on subgrade materials in cold regions