Experimental observations that simulated active-layer deepening drives deeper rock fracture
The impact of changes in active-layer thickness on the depth of pervasive macrofracture (brecciation) in frost-susceptible bedrock is unclear but important to understanding its physical properties and geohazard potential. Here we report results from a laboratory experiment to test the hypothesis tha...
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ftunivsussex:oai:sro.sussex.ac.uk:89351 2023-07-30T04:06:20+02:00 Experimental observations that simulated active-layer deepening drives deeper rock fracture Maji, Vikram Murton, Julian B 2020-02-27 application/pdf http://sro.sussex.ac.uk/id/eprint/89351/ http://sro.sussex.ac.uk/id/eprint/89351/1/Accepted%20ms%20PPP.pdf https://doi.org/10.1002/ppp.2041 en eng Wiley http://sro.sussex.ac.uk/id/eprint/89351/1/Accepted%20ms%20PPP.pdf Maji, Vikram and Murton, Julian B (2020) Experimental observations that simulated active-layer deepening drives deeper rock fracture. Permafrost and Periglacial Processes. pp. 1-15. ISSN 1045-6740 QE0001 General Including geographical divisions Article PeerReviewed 2020 ftunivsussex https://doi.org/10.1002/ppp.2041 2023-07-11T20:42:10Z The impact of changes in active-layer thickness on the depth of pervasive macrofracture (brecciation) in frost-susceptible bedrock is unclear but important to understanding its physical properties and geohazard potential. Here we report results from a laboratory experiment to test the hypothesis that active-layer deepening drives an increase in the depth of brecciation. The experiment simulated active-layer deepening in 300 mm cubic blocks of limestone (chalk) and sandstone. Temperature, surface heave and strain at depth were measured during 16 freeze–thaw cycles. Macrocracks photographed at intervals were digitally analysed to visualise crack growth and to quantify crack inclination and length. In chalk, an upper horizon of macrocracks developed first at about 100 mm depth in a shallow thaw active layer during cycles 1–8, followed by a lower horizon at about 175‒225 mm depth in a deeper thaw active layer during cycles 9–16. The longest cracks (>35 mm) were most common at inclinations of 0–30° from horizontal, and numerous cracks <5 to 15 mm long developed at inclinations of 40–50°, with some longer vertical to subvertical cracks linking the two brecciated horizons. Overall, the observations support the hypothesis that a thickening active layer drives deeper rock fracture by ice segregation. Article in Journal/Newspaper Permafrost and Periglacial Processes University of Sussex: Sussex Research Online Permafrost and Periglacial Processes 31 2 296 310 |
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Open Polar |
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University of Sussex: Sussex Research Online |
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ftunivsussex |
language |
English |
topic |
QE0001 General Including geographical divisions |
spellingShingle |
QE0001 General Including geographical divisions Maji, Vikram Murton, Julian B Experimental observations that simulated active-layer deepening drives deeper rock fracture |
topic_facet |
QE0001 General Including geographical divisions |
description |
The impact of changes in active-layer thickness on the depth of pervasive macrofracture (brecciation) in frost-susceptible bedrock is unclear but important to understanding its physical properties and geohazard potential. Here we report results from a laboratory experiment to test the hypothesis that active-layer deepening drives an increase in the depth of brecciation. The experiment simulated active-layer deepening in 300 mm cubic blocks of limestone (chalk) and sandstone. Temperature, surface heave and strain at depth were measured during 16 freeze–thaw cycles. Macrocracks photographed at intervals were digitally analysed to visualise crack growth and to quantify crack inclination and length. In chalk, an upper horizon of macrocracks developed first at about 100 mm depth in a shallow thaw active layer during cycles 1–8, followed by a lower horizon at about 175‒225 mm depth in a deeper thaw active layer during cycles 9–16. The longest cracks (>35 mm) were most common at inclinations of 0–30° from horizontal, and numerous cracks <5 to 15 mm long developed at inclinations of 40–50°, with some longer vertical to subvertical cracks linking the two brecciated horizons. Overall, the observations support the hypothesis that a thickening active layer drives deeper rock fracture by ice segregation. |
format |
Article in Journal/Newspaper |
author |
Maji, Vikram Murton, Julian B |
author_facet |
Maji, Vikram Murton, Julian B |
author_sort |
Maji, Vikram |
title |
Experimental observations that simulated active-layer deepening drives deeper rock fracture |
title_short |
Experimental observations that simulated active-layer deepening drives deeper rock fracture |
title_full |
Experimental observations that simulated active-layer deepening drives deeper rock fracture |
title_fullStr |
Experimental observations that simulated active-layer deepening drives deeper rock fracture |
title_full_unstemmed |
Experimental observations that simulated active-layer deepening drives deeper rock fracture |
title_sort |
experimental observations that simulated active-layer deepening drives deeper rock fracture |
publisher |
Wiley |
publishDate |
2020 |
url |
http://sro.sussex.ac.uk/id/eprint/89351/ http://sro.sussex.ac.uk/id/eprint/89351/1/Accepted%20ms%20PPP.pdf https://doi.org/10.1002/ppp.2041 |
genre |
Permafrost and Periglacial Processes |
genre_facet |
Permafrost and Periglacial Processes |
op_relation |
http://sro.sussex.ac.uk/id/eprint/89351/1/Accepted%20ms%20PPP.pdf Maji, Vikram and Murton, Julian B (2020) Experimental observations that simulated active-layer deepening drives deeper rock fracture. Permafrost and Periglacial Processes. pp. 1-15. ISSN 1045-6740 |
op_doi |
https://doi.org/10.1002/ppp.2041 |
container_title |
Permafrost and Periglacial Processes |
container_volume |
31 |
container_issue |
2 |
container_start_page |
296 |
op_container_end_page |
310 |
_version_ |
1772818885060329472 |