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Strength Analysis of Fragipans in Some Loess‐derived Soils in Louisiana
Author(s) -
Inman B. L.,
Bryant R. B.,
Hudnall W. H.
Publication year - 1989
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1989.03615995005300030043x
Subject(s) - loess , soil water , water content , geology , moisture , ridge , soil science , bulk density , geotechnical engineering , mineralogy , geomorphology , materials science , composite material , paleontology
The objective of this study was to quantify the strength characteristics of fragipans found in selected loess‐derived soils in northeastern Louisiana. Three study sites were selected on the Macon Ridge, which is blanketed by a Peoria loess. Two sites were selected on the Bastrop Ridge, which is covered by a pre‐Peoria loess. The unconfined compression (UC) test was used to quantify the strength characteristics of (i) undisturbed fragipan material taken at field moisture, (ii) remolded fragipan material equilibrated to the same moisture content and packed to the same density as the undisturbed samples, and (iii) oven‐dried undisturbed fragipan samples. A range of strength occurred among the undisturbed samples due to natural fabric differences. Remolded samples had lower strengths compared to the undisturbed samples. In general, higher sensitivity values for fragipan horizons from the Macon Ridge sites indicated that rigidity in these fragipan horizons is derived in part from binding agents. Low sensitivity values measured on fragipans from the Bastrop Ridge sites indicated that cohesive binding agents have little effect in providing rigidity for these fragipan horizons. Dried undisturbed fragipan material exhibited strength values a full order of magnitude greater than those measured on samples tested at field moisture contents. Results indicate that the fragipans in soils developed in older loess deposits on the Bastrop Ridge have a lower component of strength derived from interparticulate binding agents than those fragipans in soils developed in the younger loess deposits on the Macon Ridge.