On the difficulties of geotechnical sampling and practical estimates of the strength of a weakly bonded volcanic soil

Verfasser / Beitragende:
[Elif Avşar, Resat Ulusay, Ömer Aydan, Mahmut Mutlutürk]
Ort, Verlag, Jahr:
2015
Enthalten in:
Bulletin of Engineering Geology and the Environment, 74/4(2015-11-01), 1375-1394
Format:
Artikel (online)
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024 7 0 |a 10.1007/s10064-014-0710-9  |2 doi 
035 |a (NATIONALLICENCE)springer-10.1007/s10064-014-0710-9 
245 0 0 |a On the difficulties of geotechnical sampling and practical estimates of the strength of a weakly bonded volcanic soil  |h [Elektronische Daten]  |c [Elif Avşar, Resat Ulusay, Ömer Aydan, Mahmut Mutlutürk] 
520 3 |a Volcanic soils, which cover significant parts of the world's surface, including urban areas, structures and infrastructures, may create geo-engineering problems. These soils exhibit distinctive geomechanical behaviours that are a consequence of their formation history, mineralogy and structure. This paper presents the results of an experimental investigation into geo-engineering properties of a volcanic soil observed in the city of Isparta, Turkey. The study focuses on the difficulties experienced in geotechnical sampling of the soil, its microstructural, mineralogical and physical properties, and particularly the estimation of its uniaxial compressive strength (UCS) using practical approaches. For this purpose, laboratory experiments covering the determination of mineralogical-petrographical and geomechanical properties, such as physical properties, UCS, and needle penetration index (NPI) using a specially manufactured needle, were conducted. The volcanic soil is weakly bonded, highly porous, well-graded silty sand and has a hypocrystalline texture. The weak bonding of the soil is volcanic ash formed by disintegration of volcanic glass, and the soil has some voids and a considerable amount of intact bonding between grains. The most important difficulty associated with this volcanic soil is field sampling and sample preparation for laboratory testing due to the weak bonding that governs internal stability. The UCS of the soil ranges between 29 and 132kPa, and except for in a few samples, the UCS is lower than 100kPa. The soil generally shows strain softening behaviour during the UCS tests; however, a few samples failed in a brittle fashion. As the natural water content and degree of saturation increases above approximately 11 and 42%, respectively, there is a decline in the UCS of the soil. This is due to the increased exposure to water, which apparently softens the bonding, causing some loss of interlocking among the grains. Statistical evaluations suggest that the UCS of the volcanic soil can be estimated from the NPI using a needle with a diameter of 1.7mm. In practical terms, the study provides some approaches and recommendations for the estimation of strength of weakly bonded volcanic soils for which geotechnical sampling is extremely difficult and/or impossible. 
540 |a Springer-Verlag Berlin Heidelberg, 2014 
690 7 |a Volcanic soil  |2 nationallicence 
690 7 |a Uniaxial compressive strength  |2 nationallicence 
690 7 |a Needle penetration index  |2 nationallicence 
690 7 |a Laboratory sampling  |2 nationallicence 
690 7 |a Prediction equation  |2 nationallicence 
690 7 |a Microstructure  |2 nationallicence 
700 1 |a Avşar  |D Elif  |u Department of Geological Engineering, Selçuk University, Konya, Turkey  |4 aut 
700 1 |a Ulusay  |D Resat  |u Department of Geological Engineering, Hacettepe University, Beytepe, 06800, Ankara, Turkey  |4 aut 
700 1 |a Aydan  |D Ömer  |u Department of Civil Engineering and Architecture, University of the Ryukyus, Okinawa, Japan  |4 aut 
700 1 |a Mutlutürk  |D Mahmut  |u Department of Geological Engineering, Süleyman Demirel University, Isparta, Turkey  |4 aut 
773 0 |t Bulletin of Engineering Geology and the Environment  |d Springer Berlin Heidelberg  |g 74/4(2015-11-01), 1375-1394  |x 1435-9529  |q 74:4<1375  |1 2015  |2 74  |o 10064 
856 4 0 |u https://doi.org/10.1007/s10064-014-0710-9  |q text/html  |z Onlinezugriff via DOI 
898 |a BK010053  |b XK010053  |c XK010000 
900 7 |a Metadata rights reserved  |b Springer special CC-BY-NC licence  |2 nationallicence 
908 |D 1  |a research-article  |2 jats 
949 |B NATIONALLICENCE  |F NATIONALLICENCE  |b NL-springer 
950 |B NATIONALLICENCE  |P 856  |E 40  |u https://doi.org/10.1007/s10064-014-0710-9  |q text/html  |z Onlinezugriff via DOI 
950 |B NATIONALLICENCE  |P 700  |E 1-  |a Avşar  |D Elif  |u Department of Geological Engineering, Selçuk University, Konya, Turkey  |4 aut 
950 |B NATIONALLICENCE  |P 700  |E 1-  |a Ulusay  |D Resat  |u Department of Geological Engineering, Hacettepe University, Beytepe, 06800, Ankara, Turkey  |4 aut 
950 |B NATIONALLICENCE  |P 700  |E 1-  |a Aydan  |D Ömer  |u Department of Civil Engineering and Architecture, University of the Ryukyus, Okinawa, Japan  |4 aut 
950 |B NATIONALLICENCE  |P 700  |E 1-  |a Mutlutürk  |D Mahmut  |u Department of Geological Engineering, Süleyman Demirel University, Isparta, Turkey  |4 aut 
950 |B NATIONALLICENCE  |P 773  |E 0-  |t Bulletin of Engineering Geology and the Environment  |d Springer Berlin Heidelberg  |g 74/4(2015-11-01), 1375-1394  |x 1435-9529  |q 74:4<1375  |1 2015  |2 74  |o 10064