Influence of Plunger Stress on Resilient Modulus of Forest Subgrade Soils Obtained from Cyclic CBR Test

The low load-bearing capacity of subgrade soils is typical for forest roads. For the determination of the resilient modulus M<sub>r</sub> of unbound natural as well as recycled materials, a laboratory triaxial test with cyclic loading is generally preferred. For low volume roads, includi...

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Autores principales:	Lenka Ševelová, Aleš Florian, Jaroslav Žák
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	low volume road pavement soil resilient modulus CBR cyclic Plant ecology QK900-989
Acceso en línea:	https://doaj.org/article/9b2487aa2035431eac1ba8bc4c5835f4
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id	oai:doaj.org-article:9b2487aa2035431eac1ba8bc4c5835f4
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spelling	oai:doaj.org-article:9b2487aa2035431eac1ba8bc4c5835f42021-11-25T17:37:28ZInfluence of Plunger Stress on Resilient Modulus of Forest Subgrade Soils Obtained from Cyclic CBR Test10.3390/f121114561999-4907https://doaj.org/article/9b2487aa2035431eac1ba8bc4c5835f42021-10-01T00:00:00Zhttps://www.mdpi.com/1999-4907/12/11/1456https://doaj.org/toc/1999-4907The low load-bearing capacity of subgrade soils is typical for forest roads. For the determination of the resilient modulus M<sub>r</sub> of unbound natural as well as recycled materials, a laboratory triaxial test with cyclic loading is generally preferred. For low volume roads, including forest roads, an alternative method of the cyclic CBR test, which uses standard CBR devices for repeated loading, is being tested and applied in practice. For forest subgrade soils, the procedure for determining the modulus M<sub>r</sub> based on cyclic loading of the specimen to a constant penetration depth of 2.54 mm was verified. This procedure was tested on an extensive dataset obtained from 11 forest roads in the Czech Republic, which was then statistically evaluated. The obtained results showed disproportionately high mean values as well as high random variability. Further data analysis revealed that the reason seemed to be the chosen test methodology. When using this procedure for forest soils, high values of plunger stress can occur, which for many types of soils greatly exceed their maximum load-bearing capacity. As result, the modulus M<sub>r</sub> is determined at unrealistically high plunger stress values and in many cases on the disrupted specimen. The necessary solution to this shortcoming is to censor the results of the cyclic CBR test, i.e., to exclude unrealistic values of the modulus M<sub>r</sub> determined at plunger stresses exceeding the limit values.Lenka ŠevelováAleš FlorianJaroslav ŽákMDPI AGarticlelow volume roadpavementsoilresilient modulusCBRcyclicPlant ecologyQK900-989ENForests, Vol 12, Iss 1456, p 1456 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	low volume road pavement soil resilient modulus CBR cyclic Plant ecology QK900-989
spellingShingle	low volume road pavement soil resilient modulus CBR cyclic Plant ecology QK900-989 Lenka Ševelová Aleš Florian Jaroslav Žák Influence of Plunger Stress on Resilient Modulus of Forest Subgrade Soils Obtained from Cyclic CBR Test
description	The low load-bearing capacity of subgrade soils is typical for forest roads. For the determination of the resilient modulus M<sub>r</sub> of unbound natural as well as recycled materials, a laboratory triaxial test with cyclic loading is generally preferred. For low volume roads, including forest roads, an alternative method of the cyclic CBR test, which uses standard CBR devices for repeated loading, is being tested and applied in practice. For forest subgrade soils, the procedure for determining the modulus M<sub>r</sub> based on cyclic loading of the specimen to a constant penetration depth of 2.54 mm was verified. This procedure was tested on an extensive dataset obtained from 11 forest roads in the Czech Republic, which was then statistically evaluated. The obtained results showed disproportionately high mean values as well as high random variability. Further data analysis revealed that the reason seemed to be the chosen test methodology. When using this procedure for forest soils, high values of plunger stress can occur, which for many types of soils greatly exceed their maximum load-bearing capacity. As result, the modulus M<sub>r</sub> is determined at unrealistically high plunger stress values and in many cases on the disrupted specimen. The necessary solution to this shortcoming is to censor the results of the cyclic CBR test, i.e., to exclude unrealistic values of the modulus M<sub>r</sub> determined at plunger stresses exceeding the limit values.
format	article
author	Lenka Ševelová Aleš Florian Jaroslav Žák
author_facet	Lenka Ševelová Aleš Florian Jaroslav Žák
author_sort	Lenka Ševelová
title	Influence of Plunger Stress on Resilient Modulus of Forest Subgrade Soils Obtained from Cyclic CBR Test
title_short	Influence of Plunger Stress on Resilient Modulus of Forest Subgrade Soils Obtained from Cyclic CBR Test
title_full	Influence of Plunger Stress on Resilient Modulus of Forest Subgrade Soils Obtained from Cyclic CBR Test
title_fullStr	Influence of Plunger Stress on Resilient Modulus of Forest Subgrade Soils Obtained from Cyclic CBR Test
title_full_unstemmed	Influence of Plunger Stress on Resilient Modulus of Forest Subgrade Soils Obtained from Cyclic CBR Test
title_sort	influence of plunger stress on resilient modulus of forest subgrade soils obtained from cyclic cbr test
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/9b2487aa2035431eac1ba8bc4c5835f4
work_keys_str_mv	AT lenkasevelova influenceofplungerstressonresilientmodulusofforestsubgradesoilsobtainedfromcycliccbrtest AT alesflorian influenceofplungerstressonresilientmodulusofforestsubgradesoilsobtainedfromcycliccbrtest AT jaroslavzak influenceofplungerstressonresilientmodulusofforestsubgradesoilsobtainedfromcycliccbrtest
_version_	1718412182240100352

Influence of Plunger Stress on Resilient Modulus of Forest Subgrade Soils Obtained from Cyclic CBR Test

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