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t013-neel.txt (4761B) | |
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1 Today, [1]Indraneel Kasmalkar had his paper published in [2]Journal of | |
2 Geophysical Research: Earth Surface. Congratulations Neel! He used my so… | |
3 [3]sphere, and sheared a granular assembledge with a non-trivial forcing… | |
4 order to learn more about subglacial sediment behavior. | |
5 | |
6 Abstract | |
7 | |
8 Shear Variation at the Ice-Till Interface Changes the Spatial Distri… | |
9 of Till Porosity and Meltwater Drainage | |
10 | |
11 Indraneel Kasmalkar(1), Anders Damsgaard(2), Liran Goren(3), Jenny S… | |
12 (1,4,5) | |
13 | |
14 1: Department of Computational and Mathematical Engineering, Stanford | |
15 University, CA, USA | |
16 2: Department of Geoscience, Aarhus University, Denmark | |
17 3: Department of Earth and Environmental Sciences, Ben-Gurion Univer… | |
18 the Negev, Beer-Sheva, Israel | |
19 4: Department of Geophysics, Stanford University, CA, USA | |
20 5: Department of Civil and Environmental Engineering, Stanford Unive… | |
21 CA, USA | |
22 | |
23 Plain-language summary: | |
24 The ice at the base of certain glaciers moves over soft sediments th… | |
25 route meltwater through the pore spaces in between the sediment grai… | |
26 ice shears the sediment, but it is not clear if this slow shearing is | |
27 capable of changing the structure or volume of the pore space, or th… | |
28 of the meltwater that flows through the sediment. To study the relat… | |
29 between the shearing of the sediment and the changes in its pore spa… | |
30 use computer simulations that portray the sediment as a collection of | |
31 closely packed spherical grains, where the pores are filled with mel… | |
32 To shear the simulated sediment, the grains at the top are pushed wi… | |
33 fixed speeds in the horizontal direction. Despite the slow shear, wh… | |
34 generally thought of as having no effect on pore space, our results … | |
35 that shearing changes the sizes of the pores in between the grains, … | |
36 large pores are formed near the top of the sediment layer. If the gr… | |
37 the top are pushed with uneven speeds, then the largest pores are fo… | |
38 the areas where grain speeds vary the most. We show that the exchang… | |
39 meltwater between neighboring pores is faster than the movement of t… | |
40 grains, indicating that the meltwater can adjust quickly to changing… | |
41 space. | |
42 | |
43 Abstract: | |
44 Many subglacial environments consist of a fine-grained, deformable s… | |
45 bed, known as till, hosting an active hydrological system that routes | |
46 meltwater. Observations show that the till undergoes substantial she… | |
47 deformation as a result of the motion of the overlying ice. The defo… | |
48 of the till, coupled with the dynamics of the hydrological system, is | |
49 further affected by the substantial strain rate variability in subgl… | |
50 conditions resulting from spatial heterogeneity at the bed. However,… | |
51 not clear if the relatively low magnitudes of strain rates affect th… | |
52 structure or its hydrology. We study how laterally varying shear alo… | |
53 ice-bed interface alters sediment porosity and affects the flux of | |
54 meltwater through the pore spaces. We use a discrete element model | |
55 consisting of a collection of spherical, elasto-frictional grains wi… | |
56 water-saturated pore spaces to simulate the deformation of the granu… | |
57 bed. Our results show that a deforming granular layer exhibits subst… | |
58 spatial variability in porosity in the pseudo-static shear regime, w… | |
59 shear strain rates are relatively low. In particular, laterally vary… | |
60 shear at the shearing interface creates a narrow zone of elevated po… | |
61 which has increased susceptibility to plastic failure. Despite the c… | |
62 in porosity, our analysis suggests that the pore pressure equilibrat… | |
63 near-instantaneously relative to the deformation at critical state, | |
64 inhibiting potential strain rate dependence of the deformation cause… | |
65 bed hardening or weakening resulting from pore pressure changes. We … | |
66 shear variation to porosity evolution and drainage element formation… | |
67 actively deforming subglacial tills. | |
68 | |
69 Links and references: | |
70 | |
71 • [4]Publication on journal webpage (closed access) | |
72 • [5]Preprint PDF | |
73 • [6]Simulation software | |
74 • [7]Visualization of example simulation | |
75 | |
76 | |
77 References: | |
78 | |
79 [1] mailto:[email protected] | |
80 [2] https://agupubs.onlinelibrary.wiley.com/journal/19422466 | |
81 [3] https://src.adamsgaard.dk/sphere | |
82 [4] https://doi.org/10.1029/2021JF006460 | |
83 [5] https://adamsgaard.dk/papers/Kasmalkar%20et%20al%202021%20Shear%20va… | |
84 [6] https://src.adamsgaard.dk/sphere | |
85 |