Key Points:• The settling depth in granular media is independent of gravity • The settling time scales like g −1∕2• Layering driven by granular sedimentation should be similar Abstract While the penetration of objects into granular media is well-studied, there is little understanding of how objects settle in gravities, g eff , different from that of Earth-a scenario potentially relevant to the geomorphology of planets and asteroids and also to their exploration using man-made devices. By conducting experiments in an accelerating frame, we explore g eff ranging from 0.4 g to 1.2 g. Surprisingly, we find that the rest depth is independent of g eff and also that the time required for the object to come to rest scales like g. With discrete element modeling simulations, we reproduce the experimental results and extend the range of g eff to objects as small as asteroids and as large as Jupiter. Our results shed light on the initial stage of sedimentation into dry granular media across a range of celestial bodies and also have implications for the design of man-made, extraterrestrial vehicles and structures.A loosely packed bed of sand sits precariously on the fence between mechanically stable and flowing states. This has especially strong implications not only for the geomorphology of the Earth but for that of extraterrestrial bodies where the surface is predominantly granular [Shinbrot et al., 2004;Almeida et al., 2008;Thomas and Robinson, 2005;Asphaug, 2007;Miyamoto et al., 2007]. Beyond surface morphology, extraterrestrial exploration and development requires navigation in and on loose granular media, but little is known regarding how objects settle in granular systems with gravitational conditions different from Earth's. Such understanding may have helped prevent the difficulties encountered by the Mars rover, Spirit, as it sank into and tried to escape from a sand dune in 2009 (see, for example, http://marsrover.nasa.gov/spotlight/ 20091019a.html). Other endeavors, such as asteroid or lunar mining [Elvis, 2012], will certainly involve both navigation and construction on granular surfaces.During the last decade, our understanding of the resistance to objects penetrating into granular media under Earth-like conditions has advanced quickly [Uehara et al., 2003;Walsh et al., 2003;Boudet et al., 2006;de Vet and de Bruyn, 2007;Katsuragi and Durian, 2007;Pacheco-Vázquez et al., 2011;Katsuragi, 2012;Kondic et al., 2012;Ruiz-Suárez, 2013]. A handful of attempts have mimicked low-gravity conditions [Goldman and Umbanhowar, 2008;Brzinski and Durian, 2010;Chen et al., 2009;Constantino et al., 2011;Dorbolo et al., 2013;Brzinski et al., 2013], mainly by using air-fluidized granular beds or grains immersed in a liquid, but the main focus has typically been on the role of intruder velocity or grain friction. Here we focus exclusively on the role of gravity as an object settles into granular media. By conducting experiments in a freely falling reference frame, we are able to create true low-and high-gravity conditions as a sphere...

International audienceUnderstanding the penetration dynamics of intruders in granular beds is relevant not only for fundamental Physics, but also for geophysical processes and construction on sediments or granular soils in areas potentially affected by earthquakes. While the penetration of intruders in two dimensional (2D) laboratory granular beds can be followed using video recording, it is useless in three dimensional (3D) beds of non-transparent materials such as common sand. Here we propose a method to quantify the sink dynamics of an intruder into laterally shaken granular beds based on the temporal correlations between the signals from a reference accelerometer fixed to the shaken granular bed, and a probe accelerometer deployed inside the intruder. Due to its analogy with the working principle of a lock in amplifier, we call this technique Lock in accelerometry (LIA). During Earthquakes, some soils can lose their ability to sustain shear and deform, causing subsidence and sometimes substantial building damage due to deformation or tumblin

We study the behavior of cylindrical objects as they sink into a dry granular bed fluidized due to lateral oscillations, in order to shed light on human constructions and other objects. Somewhat unexpectedly, we have found that, within a large range of lateral shaking powers, cylinders with flat bottoms sink vertically, while those with a "foundation"consisting in a shallow ring attached to their bottom, tilt besides sinking. The latter scenario seems to dominate independently from the nature of the foundation when strong enough lateral vibrations are applied. We are able to reproduce the observed behavior by quasi-2D numerical simulations, and the vertical sink dynamics with the help of a Newtonian equation of motion for the intruder.

We study the behavior of cylindrical objects as they sink into a dry granular bed fluidized due to lateral oscillations. Somewhat unexpectedly, we have found that, within a large range of lateral shaking powers, cylinders with flat bottoms sink vertically, while those with a "foundation"consisting in a shallow ring attached to their bottom, tilt besides sinking. The latter scenario seems to dominate independently from the nature of the foundation when strong enough lateral vibrations are applied. We are able to explain the observed behavior by quasi-2D numerical simulations, which also demonstrate the influence of the intruder's aspect ratio. The vertical sink dynamics is explained with the help of a Newtonian equation of motion for the intruder. Our findings may shed light on the behavior of buildings and other man-made constructions during earthquakes.