1 00:00:00,400 --> 00:00:02,240 - [Oliver] I am Doctor Oliver Taylor. 2 00:00:02,240 --> 00:00:05,790 I'm a geotechnical engineer here at the US Army Engineer 3 00:00:05,790 --> 00:00:07,130 Research and Development Center. 4 00:00:07,130 --> 00:00:10,590 The project is from particles to planets. 5 00:00:10,590 --> 00:00:14,600 It's unlocking the physics of near-surface soil mechanics. 6 00:00:14,600 --> 00:00:18,520 What we are studying is we are studying how particles 7 00:00:18,520 --> 00:00:21,920 go from single grains to larger entities and 8 00:00:21,920 --> 00:00:25,820 how they fail and the mechanics of why this occurs. 9 00:00:25,820 --> 00:00:28,820 So, in my line of work when assumptions fail, 10 00:00:28,820 --> 00:00:29,820 soldiers die. 11 00:00:29,820 --> 00:00:34,210 So what this really means is when we don't understand 12 00:00:34,210 --> 00:00:38,697 what's going on well enough, unintended consequences 13 00:00:38,697 --> 00:00:41,080 occur, not might occur. 14 00:00:41,080 --> 00:00:44,250 But they do occur and those end up costing lives. 15 00:00:44,250 --> 00:00:46,710 And that's what we're trying to mitigate. 16 00:00:46,710 --> 00:00:50,270 So let's think about the importance of this in a 17 00:00:50,270 --> 00:00:52,470 relatively relatable example. 18 00:00:52,470 --> 00:00:55,670 If I have a road and I drive my armored personnel 19 00:00:55,670 --> 00:00:57,350 carrier down this road and it's dry, 20 00:00:57,350 --> 00:01:00,280 I can take that vehicle and I can screw down the road 21 00:01:00,280 --> 00:01:02,030 very fast and it's doesn't do anything. 22 00:01:02,030 --> 00:01:04,260 Now if it rains a little bit more, 23 00:01:04,260 --> 00:01:08,370 what ends up happening is those vehicles then get stuck. 24 00:01:08,370 --> 00:01:10,850 And when they're stuck and they can't go anywhere 25 00:01:10,850 --> 00:01:12,990 then that's where soldiers get trapped. 26 00:01:12,990 --> 00:01:15,600 So we're trying to understand the mechanics behind 27 00:01:15,600 --> 00:01:18,150 the soil to prevent this from happening, 28 00:01:18,150 --> 00:01:22,650 so that we understand when and how the soil is 29 00:01:22,650 --> 00:01:24,650 going to give way. 30 00:01:24,650 --> 00:01:27,840 So what we're doing is we're taking particles here. 31 00:01:27,840 --> 00:01:29,450 We have two nominal grain sizes. 32 00:01:29,450 --> 00:01:30,840 And we're going to apply some energy. 33 00:01:30,840 --> 00:01:33,690 We apply through a compaction hammer. 34 00:01:33,690 --> 00:01:36,720 This compaction hammer then allows particle chains 35 00:01:36,720 --> 00:01:40,560 to form and bonds to build between the sand. 36 00:01:40,560 --> 00:01:42,990 And that allows us to create a structure. 37 00:01:42,990 --> 00:01:46,700 This structure then is able to stand unsupported 38 00:01:46,700 --> 00:01:49,000 and then hold weights and we're going to load it 39 00:01:49,000 --> 00:01:50,530 in such a manner to show this. 40 00:01:50,530 --> 00:01:52,470 We're gonna go through all the weights that are here 41 00:01:52,470 --> 00:01:54,560 and we're gonna load these samples up and they do 42 00:01:54,560 --> 00:01:56,620 hold a tremendous amount of weight. 43 00:01:56,620 --> 00:02:01,450 The dry sand actually holds more weight than wet sand. 44 00:02:01,450 --> 00:02:04,860 And what we find in these materials is the sand, 45 00:02:04,860 --> 00:02:08,730 it fails completely opposite from how we have always 46 00:02:08,730 --> 00:02:11,320 assumed the particle material to fail. 47 00:02:11,320 --> 00:02:15,690 The chains that develop in the sand castles here, 48 00:02:15,690 --> 00:02:18,170 the strength is contained up at the top. 49 00:02:18,170 --> 00:02:19,590 They fail at the top. 50 00:02:19,590 --> 00:02:22,670 They have more of an explosive-type failure and 51 00:02:22,670 --> 00:02:25,190 the weights go straight down the center axis. 52 00:02:25,190 --> 00:02:27,340 So we're gonna start with our loading and 53 00:02:27,340 --> 00:02:29,340 we're gonna capture it under high speed and 54 00:02:29,340 --> 00:02:32,370 then we're gonna show that after these things have failed 55 00:02:32,370 --> 00:02:34,283 that it goes back to being particles. 56 00:02:40,910 --> 00:02:43,500 We started out with particles of sand and 57 00:02:43,500 --> 00:02:45,672 we went right back to particles of sand. 58 00:02:45,672 --> 00:02:49,060 There's nothing that's holding everything together 59 00:02:49,060 --> 00:02:50,810 other than the chains that developed. 60 00:02:50,810 --> 00:02:52,620 So we started from particles. 61 00:02:52,620 --> 00:02:53,820 We went to an element and 62 00:02:53,820 --> 00:02:55,083 we returned to particles.