Carving Crazy Horse: Art and Engineering of Blasting Massive Rock Monuments Prof. Charles Dowding, Northwestern University Wednesday, April 14, 2004, 3:30 p.m. College of Engineering University of Wisconsin-Madison 1800 Engineering Hall 1415 Engineering Drive Madison, WI 53706 [Tuncer Edil, Chair, UW-Madison Geological Engineering Program] Good afternoon. There are people coming from different parts of campus, but we'll get started. I'm Tuncer Edil, Chair of the Geological Engineering Program, which is the main sponsor of this university lecture. The Geological Engineering Program is an interdisciplinary program supported by faculty from three colleges and five departments, but primarily from the Civil and Environmental Engineering and Geology and Geophysics Departments. The other sponsors of this lecture include the Department of Art, Department of Art History, Department of Civil and Environmental Engineering, and Wisconsin Initiative for Science Literacy. We are very pleased to have Prof. Chuck Dowding of Northwestern University as our lecturer. He is a designated Sigma Xi distinguished lecturer for 2003-2004. He is a member of the board of directors of the International Society of Explosive Engineers and founded Digital Vibrations, Inc., the first company to perfect remote digital blast vibration monitoring in the early 1980s. He has written widely in the field of geotechnical engineering and is best known for his three books: Construction Vibrations, Blast Vibration Monitoring and Control, and Geomeasurements by Pulsing TER Cables and Probes. Dr. Dowding received his bachelor of science degree from the University of Colorado and his PhD from the University of Illinois, and he was a Royal Norwegian Fellow in the Norwegian Geotechnical Institute, which is one of the leading geotechnical organizations in the world. He taught at MIT before he joined Northwestern University. He, along with coauthors, received the Applied Research Award from the National Rock Mechanics Committee for their work on blast-induced cracking of structures. Currently, he is developing systems to autonomously monitor and display the status of critical facilities through the Northwestern Infrastructure Technology Institute. Chuck Dowding is an internationally renowned and recognized engineering leader, with high stature, and it's a particular pleasure of mine -- since I knew him since his PhD days at Illinois. With that, I would like to invite you to present us your lecture on Carving Crazy Horse: Art and Engineering of Blasting Massive Rock Sculptures. [Dowding] Thank you, Tuncer. It's a pleasure to be here in Madison. I thought that it would be fun to connect with the audience and share with you the ten reasons why I'm really a closet Badger, before I started my presentation. The first and foremost is, I'm really a closet Green Bay Packer fan. Hey, who could forget Vince Lombardi. Both my wife, Jane, who is in the back here, and I were born in Milwaukee, in the same hospital, even. I spent summers in Sheboygan with my grandmother eating bratwurst and fishing for perch. Jane's cousins, some of whom are here, are hog farmers in Rochester. Let's see, that makes number four. This one's real hard to do. We have four second cousins who are currently here as students at the University of Wisconsin. Janes' uncle was a graduate student on the team that invented warfarin, which is Coumadin, which actually is the first drug that began to fund the Wisconsin Alumni Research Foundation, which is a considerable power on your campus at this time. And my mother-in-law, this is numbered seven, the lucky number, is a University of Wisconsin graduate, and I can't ever forget that. Jane studied art history here 40 years ago, so we're very pleased that the art history department has seen fit to cosponsor this. And, number nine, I love to sit on the veranda at the student union, which we did this noon, probably the best student union in the United States, and eat beer and drink bratwurst, or something like that. And after having a few beers you can't tell which you're doing. And lastly and not least, no Big-Ten list of why you're a closet Badger would be complete without homage to Babcock Hall ice cream. And my favorite flavors are Orange Custard and Chocolate Chip and Berry Alvarez. I'd like to thank all the folks who have helped sponsor this presentation -- my university, the Crazy Horse Foundation, my home department, and the U.S. Department of Transportation, which paid for some of my trips to Custer, South Dakota. I thought I'd divide my presentation into four parts, and I thought I would divide those four parts into the various learning styles. There are those who learn best by answering a question who or why, those who learn best by what, those that learn best by answering how, and finally those that learn best by answering what-if questions, so we're going to start divide them that way, so there should be a little something here for everyone -- any learning style that you have there'll be something that should be quite interesting for you. So, we're going to start with a little bit of the background, and who, and focus on the history of the project itself before we get into some of the what and the details into how this is conducted. First of all, some geometry. This is the Crazy Horse as compared to other large monuments in the world. As you can see, if it is completed to its entirety, it will be taller than the Pyramids at Giza. It's as high as the Washington Monument. And the outstretched arm here of Crazy Horse is nearly as long as a football field, and as you'll see shortly, can hold and folks can stand some thousand strong on that arm. The head of Crazy Horse is 90 feet tall, and it's carved in the round, and it is 1.5 times the height of the heads at Mount Rushmore, so if you cube 1.5, you come up with something that's nearly 4, and so you can understand why the folks say at Crazy Horse say that the heads at Mount Rushmore can fit inside Crazy Horse's head, not exactly linearly, but their volume can. Now Crazy Horse is carved fully in the round. What I have here are 4 photographs to try to demonstrate that. Here is the view one sees when driving in to the monument area from the west looking to the east, and if you can rotate around a little bit looking at the pointing finger of Crazy Horse back at the face, this is looking toward the north, and then get up in a helicopter and look down from that same angle, you can see all the people standing on Crazy Horse's arm, there, just to get a little idea of scale, and then rotate around 180 degrees from the first slide here showing now a view looking toward the westwith the outstretched arm and the face and all the people standing on the arm there. That's a good idea. Oh, perfect, thank you, that makes a big difference. So, this is the largest monument in the world, as I indicated before. It's carved fully in the round. This is not bas-relief as Mount Rushmore is, but in fact is fully three-dimensional in the round, including the chief, and the horse on which the chief is sitting. More interestingly, it's funded solely by donations and visitors' fees. There's no government support that is responsible for this. The question I'm sure you're interested in now is, How did this all happen. Well, the story actually began some 200 years ago with Louis and Clark's transcontinental journey. And it's interesting and kind of really fun to be doing this because this is the 200th year celebration of Louis and Clark's journey, as you may or may not know. They spent this last winter 200 years ago across the river from St. Louis in the low-rent district in Illinois. They couldn't afford the rent in St. Louis. And it wasn't until May 24th of this year that they began to paddle their way up the Missouri River. And that basically was what led to the opening of the West. Jefferson, the president at that time, and Meriwether Louis envisioned a transcontinental nation with the Indians as full partners. The Indians were to more or less administer the lands to the west and European settlers were to administer the lands to the east, and this was to be one great compact that would work out. Unfortunately, the western boundary kept moving toward the west, and there began to be less and less room for the Indians. And that coupled with the difficulty that arose from the difference in culture between the settlers and the Indians -- the settlers and miners were acquisitive. They believed in private ownership of land. The Indians, of course, believed in common ownership, and this difference in culture led to considerable friction. ------------------------------------------------------------------------------------------ 10:14:00 ------------------------------------------------------------------------------------------ And, of course, there were a series of treaties that were made with the Indians, and the Black Hills, which is the location of the Crazy Horse Monument, is the Paha Sapa, which is the sacred grounds of the Lakota, one of the tribes of the Sioux nation. That land was given to them in 1868 by treaty. Unfortunately, in 1874, gold was found in the Black Hills, and, of course, that led to the unilateral abrogation of the treaty in 1874. The Indians then, of course, became somewhat irritated by this, and that led to the Battle of the Little Bighorn, as you all recall, where Chief Sitting Bull and Crazy Horse then defeated Custer's cavalry unit in one of the more interesting Indian battles of that uprising. Chief Crazy Horse was credited with the strategy that led to that Indian victory. Now, Crazy Horse was the most revered of the Lakota as their most brilliant warrior, and he was assassinated at the age of 33 in Fort Robinson, Nebraska, which is up here in the panhandle of Nebraska. I'll bet you didn't know there was a panhandle in Nebraska. That's some little known fact of that state. One of his most famous quotes is, "My lands are where my people lie buried." and this is what the inscription will be on the monument when it's completed. This quote was elicited when a white trader sort of taunted him and asked after the defeat of the Indians, after that Battle of the Little Big Horn, he said, "Well, now big fella, you know, so where is your land now." And, of course, he then pointed to the southeast toward this, the panhandle of Nebraska and said, "My lands are where my people lie buried." Now let's fast-forward history a little bit to 1927. This wasn't too long after the Battle of the Little Big Horn, was it, it was only about 50 years or so. That's not a whole lot longer than some of us can remember. Gutzon Borglum began to carve in the Paha Sapa, Mount Rushmore Memorial, to the presidential heroes, Washington, Jefferson, Lincoln, and Roosevelt. Of course, Jefferson being the president who was responsible for the Louisiana Purchase, the biggest and best land deal the United States has probably ever made. Eight million bucks for all that land out there; that was quite a deal. Now, this was, if you think about it, this was the carving of the American presidents who abrogated the treaties to the Indians in their sacred land. Well, along about 1933, Chief Henry Standing Bear, here, on the lower right-hand side, was thinking that Indians had heroes, too; they had just as many heroes as the folks in Washington did, and was reading the, I don't know whether it was the New York Times, it was some newspaper, when he discovered and read about this fellow here, Korczak Ziolkowski, who won the popularity contest for the most popular carving at the 1933 World's Fair in New York, a carving of Paderewski, a Polish composer. He asked Ziolkowski to carve a monument in the Black Hills to show that the Indians have heroes, too. You can tell by this photograph that World War II intervened. You can tell by what Ziolkowski is wearing, which is a World War II military uniform. And, the war intervened, and in 1947 Ziolkowski finally accepted Standing Bear's offer, and he and Standing Bear toured the area around Mount Rushmore and picked this mountain, shown in the background here, Thunderhead Mountain, 18 miles from Mount Rushmore, as the mountain on which to carve Crazy Horse. Interestingly enough, this mountain is oriented such that it somewhat has a fin-like geometry, which points northeast where the hunting lands of the Sioux were oriented. In 1948, Ziolkowski, with his own funds, staked a mining claim to this mountain and began the carving, which started with a first blast. Now, what's interesting is that when I first investigated this project, I thought that perhaps this was started on an Indian reservation somewheres -- how else could you begin such a project today, looking at this with year 2000 eyes. Well it turns out that he was able to do this just by a mining claim alone, which only requires that one spend $100 a year to improve the mineral production of this particular location, which he did -- a very clever idea. Of course, any great idea requires a vision. You all know about vision statements and mission statements and what not. A carving in and of itself is not probably a sufficient vision to sustain the attention and aggregate the resources that are necessary to actually fulfill such a dream, and basically this enterprise is designed such that as, of Korczak Ziolkowski said, that the legends would not die and the dreams would not end, and there would be greatness. Basically, it's an attempt to ensure that the Indians will be remembered for their greatness. More importantly, it is intended that, in addition to the carving, and more important than that, that this be the location of the Indian Museum of North America, and in addition to that there would be created a University of Medical Training Center for the North American Indians. So in effect, these goals are, perhaps, transcendent over the goal of finishing off the carving of Crazy Horse. Now, Korczak Ziolkowski, the sculptor who was responsible for this heroic undertaking, was quite a visionary, and his dreams obviously have quite exceeded his lifetime. He passed away some 20 years ago after removing some 7 million tons of rock off the mountain. Here is is shown with his wife, Ruth. He was able to undertake this quite extensive enterprise with the help of his ten children that you see photographed here at the bottom. And so he, and his wife, along with the Crazy Horse Foundation and their ten children, are basically the sustaining, driving force behind this particular enterprise. This photograph was taken quite some time ago, and they are a good deal older than this. So that completes, then, sort of part one, who and why of this particular project. And now for the "what" part of this. I've divided that into three sections: geometry, excavation access plan, and the effects of geology. Well, as far as geometry goes, there's a relatively simple way to conceive of carving this. As Dennis the Menace said to his friend, "It's pretty simple. Just get a big piece of rock and chip off all the pieces that don't look like a horse." And of course there is the final carving that comes out of it, and, of course, you all realize it's a good deal more difficult than that, but that's the basic concept. What I thought I would do to in order to discuss the geometry is break this up into two sections, one the geometry dealing with the carving of the face itself, which is a smaller part of the overall carving, and then that dealing with the horse's head and body, which is a great deal larger than the face. This geometry here is contained in that brochure, which was at the back. For those of you who have come in late, you might want to get that on your way out. What I have here is a comparison between the head in the sculptor's shop and the field result. And to demonstrate the way in which the geometry was transferred from the model to the field scale with basically r-theta-z components, and that is the radial distance, some sort of angle, and then the vertical distance. The angle was measured by this protractor here on the top. You can see that this swings on around. R is the distance out from position (0,0,0), which is right here, sort of at the top part of Crazy Horse's head, so here's (0,0,0) in the field. So here you have this large arm of the protractor. This boom is that large arm of the protractor that swings on around, Here you see the vertical distance, which would be the vertical distance of this slider bar and then, of course, the sum of this bar minus this pointer would then give you the radial distance out from (0,0,0) at the top, and that would be done by the distance out along this boom at the top. Now that would be a good deal more difficult when, of course, carving the rest of the monument, because it would be very difficult to create a boom this long in the field that would be have any structural stability that would guarantee absolute location. ------------------------------------------------------------------------------------------ 19:59:00 ------------------------------------------------------------------------------------------ So what was done here is to locate points -- x, y, and z points -- by transferring x, y, and z locations from a physical pointing device here, and I'll show you the real, the modern way this is being done now. This is the way it all started out 25 years ago. A large stiff plate was put on the bottom. X was measured in this direction, y in this direction, and z up here, to this little pointer, and basically points all along this horse body and chief body surface were then pointed out to produce x, y, and z coordinates of the horse. And here's what they would look like on a computer. These are all the little dots, the points, you can kind of see the horses's eye here, the Crazy Horse arm pointing out in this direction. These points are then transferred from (0,0,0) points in the field with a total station, which then measures two angles and a distance, and gets the geometry within 5 millimeters, which is sufficient, in fact, as you'll see later, for the final surface when the final smoothing then takes place. Now just this last year, the coordinate geometry in control has been switched from that pointing approach to the use of laser profiling. This is a photograph, then, of the laser equipment that's used to take a photograph of the model itself and then to produce this computer model of a large number of points, so large, in fact, you can't distinguish the points from the statue itself. So, basically, we've now gone from the computer every point every meter or so to so many points that there are enough to even get the smallest detail transferred to the field. That gives you a little idea of how we transfer the model geometry from the scale in the sculptor's shop to the field itself. Then there is a good deal of engineering, in a sense, that's necessary in order to actually move the rock around. How, in fact, is this rock going to be removed, how is it going to be removed in such a way that it is done in such as fashion as to leave the remaining rock stable enough for the completion of the project. This comparison shows the amount of rock that's been removed to date. Here is the present geometry, this green line here is sort of shaped like a sagging chair and superimposed on the original photograph compared here on the right then demonstrate the amount of rock that has been removed so far to date. That rock has been removed to take away the weathered rock, which is a good deal less strong than the less weathered rock down here a distance that will allow the statue to remain more stable than it would have otherwise. And now the way that the remaining rock is to be removed, as shown here, this rock all has to be removed. There's an artist rendition then, here, of this process itself. A series of ramps are going to be excavated by blasting, as I'll describe later. Each of these ramps is 20 feet high. The excavation starts from the top down, so that the rock can be separated from the base itself and tumbled down the remaining slope. And the benches are connected by these ramps as shown here. Each bench starts at the back and rotate up to the front, are connected with each other in the front by these ramps here, and then they are one at a time removed until the surface that is within 20 feet of the final surface of the sculpture is then revealed. The rate at which this is being done at this point is 40 to 50 tons per year, and then this area here, just to get down to within a distance of 20 feet of the final surface, some 750,000 to 1,000,000 more tons of rock have to be removed in order to reveal that final surface. Now, I've put this in color maybe to make it a little more obvious. These are the benches as they are finally brought closer to the 20-foot-plus surface. Each one of these benches is 20 feet high and is relative to the (0,0,0) point at the top of Crazy Horse's head, as we talked about earlier. This is a plan view, this is an airplane view of the carving, and there are three sets of three contour lines on this. There is a set of counter lines which is the final contour of the monument, there is the 20-foot standoff distance contours, and then there are the contours of the original rock that needs to be removed. You can see there's a good deal of rock here that needs to be removed to get to the 20 feet, and then here's the 20 feet into the final sculpture. The elevations are shown here looking at 200, 220, and 240. Those are the yellow, green, and blue contour lines that are shown here. These are the ramps, then, that connect the various benches. Now, what I want to do is to begin to get into the three-dimensional problems that are going to be caused by this. So I've added to the three contour lines, the contour line at elevation 320, which is a good deal below the 240 elevation line here. And this basically is the elevation line at the nose of the horse, and shows how further back it will be from the brow of the horse, and that's an important issue that I'll be talking about later on. In order to make this even more clear, what I did was to cut the monument along this line to produce a cross-section. So basically you imagine taking a butter knife, carving the monument in half, and looking at one half of that from the side. And this is what we can see. These dots, now, are the contour lines of the benches of the final surface, this is the 20-foot standoff distance bench, these are the locations of the present rock, and you can see once when we get down to elevation 300 or so, there is a great deal of extra rock that needs to be removed in order to get to even the 20-foot standoff distance. Now those of you who are really clever in the audience realized immediately that the 20-foot standoff distance isn't 20 feet away down here at elevation 320. The reason for that is that if this were brought in there, there would be a tension zone in this location right here, and as I'll share with you later on, rock is not very happy under tension. It doesn't perform very well because of the joints that are in the field, volumes of rock that make it very, very weak in tension. And that has to be avoided at all costs, so, in order to bring this large monument to its next stage of production, it was decided to try not to develop any tension, if at all possible. So that's covered the first two stages of what, the geometry, the excavation access plan. Now let's talk about geology that I indicated earlier is important. The rock type here is a granite pegmatite. It's somewhat pinkish as you can see here in this photograph. It's a very, very strong material For those of you who aren't engineers and you might think of it as something like concrete. It's much stronger than that; however, that's probably not a bad analog to think of. There is one big difference, though, between rock and concrete, in that this rock has imperfections that are very large, very persistent, and very important. I'll show you how these play a role in the carving of the mountain even today and will play a more important role as the carving goes forward. What I like to tell my students is what's important in rock is what isn't rock. Basically, it's these rock joints, it's these imperfections that control the strength and properties of the rock. And this photograph, I think, amply demonstrates how important these imperfections are. This flow structure joint that I've shown here is a very persistent feature in this particular deposit. The fact that there are many of them, there are sort of a family of these features that are roughly parallel to each other, and are very, very persistent. As the carving was brought back to the 20-foot standoff distance, the blasters and drillers realized quite early on that all they needed to do was to end their holes down here at this elevation of this particular joint and basically just push the rock off, because it produced a situation where there was a great deal less strength along these persistent planes of discontinuity than there was in the rock mass above and below. So this is the importance of this flow structure. It's the dominant discontinuity. It's persistent. It breaks along there quite consistently during blasting. They have not conducted the detailed experiments that would be necessary in order to determine the constitutive properties of this particular feature. ------------------------------------------------------------------------------------------ 29:50:00 ------------------------------------------------------------------------------------------ Now, in addition to this dominant flow structure joint system, there are cross-flow joints that will allow the isolation of relatively large boulders during uncontrolled blasting. This is an example of one here compared to a D-8 bulldozer here on the right-hand side of this ellipse. This is the top portion of a cab of a pickup truck over here, to give you some idea of the size of the rock blocks that will be isolated if careful blasting is not followed. Now, these flow structures are going to pose some significant engineering challenges for this particular endeavor, and I want to share with you what probably one the most significant. This is a digitized shot, here, of the points of the Crazy Horse Monument. This is the arm that outstretches from Crazy Horse's chest and rests on the top mane of the horse. The span between the arm and the chest, here, and the horse's mane is some 110 feet. The arm itself would be some 30 feet in diameter, and these are just a few of those persistent flow joints that, most assuredly, will cut through that arm, and you can see how persistent they were from that last photograph, so these features will have to be stabilized before this is completely excavated here. They are currently working out plans for this. The plans range all the way from local reinforcement to some very significant post-tensioning and pre-tensioning of this arm by drilling a horizontal hole all the way in here and putting tendons in to hold that arm together, so as to eliminate any tensile stresses in this discontinuous blocky nature of the rock. So that now demonstrates the importance of geology and what isn't rock. Now let's get into exactly how all of this is done, some of the fun technology that's used in order to excavate this rock carefully. So, first of all, we'll look at the blasting issues, and then focus on the final facing finishing that smooths the rock to its present form. Now most of us, of course, have the popular conception of blasting -- you know, blasting, explosives, destruction, failure -- this is sort of an example of what most people think about when they think about explosives. Just some examples of how explosives are used safely in our life: For those of you who remember using Brownie flash cubes, that little puff of white light that produced enough light for the photograph was actually a small explosion that took place in the Brownie flash cube when you think about it. So, we put explosives close to various portions of our bodies and we don't think too much about it. The triggers in the air bags in our cars are explosive devices. Those are used in that way. For those of you who are into the Martian mountain rover, the umbilical cords were severed to allow the rover to roam, with explosive devices. So, we do use explosives in a safe fashion. I think this project demonstrates their safe use. Well, in order to place explosives in rock, there needs to be some sort of opening in which to place the explosive, and that opening is usually produced by drilling techniques. And these are some of the early public relations photographs of Korczak Ziolkowski beginning to drill the rock at Crazy Horse. I can't imagine that he really did very much of this jack-hammering here with a single jack as it is basically one hammer and one piece in steel. Basically, the advance rates are measured in inches per day with this kind of drilling technique, and is not recommended for those of you who are faint of heart. Of course, the more mechanized version of this is a jackhammer. I can't imagine he spent a whole lot of time using that, either. That doesn't really produce a high enough drilling rate to advance the holes with enough speed that, in fact, enough rock can be removed to make sufficient progress in this particular project. While these, I think, demonstrate heroic robustness of the artist, I'm not sure they necessarily demonstrate the absolute technology that was employed for most of the drilling. What I've done here is to compare, now, the advance rates for various types of technology. Here you see what is actually being used today in order to move as much rock as is necessary in this project. and I've ordered these in increasing order upwards of the various advance rates. Remember when we talked about single jacking? That was with one piece of steel and a hammer. A double-jack was with two people hitting one piece of steel, and a third person holding the steel. That's the job you didn't want. Don't ever want to get caught holding the steel. You always want to use the hammer. That's a better job. But actually better to be a drill operator with the Atlas Copco-hydraulic that can produce 10 feet per minute, as opposed to 1 foot per day with the other technology. It's come a long way since at least, I must say, the publicity photographs that were in the historical records of this particular project. Now we've got the holes drilled, and we need to begin to place the explosives. There are three basic principles for placing explosives in a hole. The last two actually are opposite to each to other and, therefore, require some sort of optimization. These three basic principles are, first of all, the rock at the bottom of the hole must be sufficiently energized to allow fragmentation at the bottom of the hole, and therefore there is a minimum explosive weight that needs to be placed at the bottom of the hole. You can understand the bottom of the drill hole is the strongest location of the drill hole and requires the greatest charge concentration. The second principle is that the entire rock mass needs to be fragmented, and therefore the explosive weight needs to be distributed sufficiently throughout the entire volume of rock to be fragmented, and that particular factor is generally called the powder factor, PF, in other words, there is kilograms per cubic meter of rock that is necessary in order to sufficiently fragment the rock for whatever purpose is intended. It varies from rock type to ultimate use of the rock. And lastly, the third principle is to prevent cracking of the remaining rock at some distance. And that is controlled by the explosive weight detonated in any instant of time. So the last two principles are the distribution of the explosive in space and the distribution of the explosive in time. And those two, then, have to be optimized so as to both fragment the rock sufficiently, but not place enough energy into the rock so as to compromise the remaining rock. In other words, we don't really want to leave fractures in the remaining rock because that's supposed to be stable. Now, what we do here in this case looking at the explosive weight detonated through instant W, we generally look at a scaled distance of R over W to some power, 1/2 or 1/3 and that is proportional to particle velocity and strain, and strain produces cracks. And that's basically the technology behind that. I'll try to keep the math to a relatively small portion of this lecture. As a matter of fact, there will be one more equation and that's it. I promise not to get too deeply into this. Now, if blasting is carried out and designed properly, the result of a good blast will leave these half casts. These are half of the final row of bore holes that you can see all along this particular blast. This is indicative of a blast where the last amount of explosive in these file bore holes was just enough to fracture the plane of rock along those bore holes and not to facture rock that will then be left behind. And that is greatly aided by use of precise detonation times, as, we'll talk a little bit about later. The other really important factor is to know exactly what this burden distance is here, and that is, at the bottom of the bore hole, we want to know the amount of rock between the hole and the free face. We need to know that very precisely. We don't want to judge that based on the distance between the borehole and the top of the bench. because many times that is not the same as the real burden below. That determines Q, and that's very important because Q is a function of this burden distance to the third power, therefore, any mismeasurement of B will result in a relatively high mismeasurement of Q. Employing a scaled distance relationship to estimate peak particle velocity, or strain -- so here we see R over W to the 1/3, and if we pick some value here, that will be our control value of peak particle velocity, say 4 inches per second, then that allows us to determine the scale distance, R over W to the 1/3. If we know what R is, we can then solve for W, the charge weight per instant of time, and then design our blast accordingly. All right, so now we've got the holes drilled. We know exactly how much explosive charge to use. Well, exactly how do we place the explosives and what is the technology that's employed in that endeavor. ------------------------------------------------------------------------------------------ 39:51:00 ------------------------------------------------------------------------------------------ The two explosive types that are employed are ammonium nitrate fuel oil in the sausages here, and PETN, which is a military explosive, which is in a small cord inside of the ammonium nitrate fuel oil tubes, which supplies a sufficient shock to detonate a relatively insensitive ammonium nitrate fuel oil. Ammonium nitrate fuel oil, while an explosive, is a relatively insensitive explosive that always needs to be associated with what's called a booster, or some other much more brisant, or explosive, explosive to actually detonate the ammonium nitrate fuel oil. The detonation itself is produced by this metal cylinder here, which is a blasting cap. These are the things you never want to pick up, because this is what can explode in your hand. It's a very dangerous device, and I'll talk to you about one of the latest developments that reduces the explosive nature of this device and greatly increases its safety. Now, one of the ways to distribute the explosive properly throughout the rock mass is to employ detonating cord. And this is cord that is used to detonate other explosives, but it's turning out to be a very important product to be employed in very precise controlled blasting situations such as this. And this cord is manufactured with explosive weights per foot on the order of 50, 100, 200, etc. A grain is an odd English apothecary measurement, which is 1/7,000th of a pound. Don't ask my why. I have no idea. But you can imagine, this is 57,000th of a pound per foot of explosive is in one of these small strands. And that, then, allows a very precise distribution of that explosive throughout the rock mass to control the fracturing and delay gas pressures which are important in controlling the back break and strain in the rock left behind. We measure particle velocities with geophones. I'm not going to go into that here today. But that instrument, then, allows us to measure the actual particle velocity and the time at which each of the holes are detonated. So this is a graph of particle velocity and time. And each one of these spikes, now, is a particular small portion of the total blast that's being detonated. Basically, that's every hole that's going off. That time of detonation is controlled by that silver blasting cap. It's controlled very precisely here. These were 17-millisecond delay intervals. And you can see by the distance of this red bar and the consistency between the peaks, that in fact that delay interval was very precisely controlled with these particular electronic detonators. So, it's very important to control this timing between the detonation of each hole. Now, to a human, this would seem like one blast. You wouldn't be able to detect the small subdivisions of the explosion that are only only 17 milliseconds apart. So, basically, this is 35 milliseconds, this is 195 milliseconds. It's a 160 milliseconds later, one-and-a-half tenths of a second between the beginning and the end of this blast. This to a human would seem like one particular event, as opposed to many small events, as demonstrated by the particle velocity time history. Now what I'd like to share with you is what I consider to be one of the most exciting recent developments in blasting technology, and that is the use of electronic detonators, which I have diagrammatically shown at the bottom here. I want to explain to you a little bit about the previous technology and how important this new development is. In order to control the millisecond timing intervals between the hole detonations, it was necessary to employ what we call pyrotechnic delays, and that would be that the millisecond delay would be controlled by the length of the explosive tube in this blasting cap. So the longer this tube, the longer the delay. And that is the result of the fact that all explosives have a given velocity of detonation, somewhere on the order of 25,000 feet per second, which is awfully fast. so you don't need to have a whole lot of distance here in order to produce that particular delay. Well, as with any chemical compound, it would degrade with time, there would be manufacturing differences, and that would lead to the potential for timing differences between that which was planned and that which was actually detonated. The latest development now employs adding a microprocessor to the blasting cap to precisely control the time of detonation. And basically the way this works is that the signal carries a charge, an amperage sufficient to charge a capacitor upstream of the microprocessor. The microprocessor then controls the timed release of that capacitance charge to a downstream capacitance charge and then subsequently releases that charge to the fuse, which ignites and detonates the base charge. Now, the reasons why this is so important are three. Number one, as you all know, when you log into your computer, you need to have a login and password. Well, this is a microprocessor, and requires the same thing. It requires a login and a password. So that if this blasting cap is ever stolen, and the thief doesn't have the password, this blasting cap can never be used as a detonating device. It's a wonderful antiterrorism device. It's one way in which we can still employ explosives around the world and make them more terror proof. As you know, this is a huge problem. In the Society of Explosive Engineers the last two years we spent almost 90 percent of our time working with the United States government trying to figure out how to regulate the explosives industry for us to continue to work, but to make it a safe and accountable operation. Secondly, usage of computer timing greatly improves the timing accuracy of the initiation times by three orders of magnitude we can control these times much, much more precisely than ever we could before. And thirdly, it avoids some relatively large timing differences that can be produced by these pyrotechnic delays. These pyrotechnic delays generally had errors of 5 percent. That doesn't sound like a whole lot of timing error, except that general blasting design requires that the signal be sent down to the blasting cap for all the blasting caps in a particular shot, so that none of the shot hole fragmentation would sever the signal. So you want to send the signal down to the initiators all at the beginning and let them sit there hot in the hole. Well, if you have hundreds of holes and you want to have 25 milliseconds between each detonator, you need to have a 500 millisecond delay to get the signal down and then you have another 500 milliseconds until the last hole goes off, and just calculate 5 percent of 1 second, which is a thousand milliseconds, and you basically have a timing error that's far greater than that 17-millisecond interval that I showed you before, and there can be misfires in that particular shot. So, those are the three reasons why this is a very, very important development. I'm not going to go into the details of this. I'd like now to get onto the final phase of finishing the carving, and that is the cautious blasting and final smoothing of the face that's necessary to actually produce the final outcome here. This is the chin, and lips, and nose of Crazy Horse shown to human scale here. We'll be talking about rock reinforcement, cautious blasting, drilling and wedging, and torching that's necessary to produce this relatively smooth final appearance of the face. So, when we talk about the cautious blasting, we'll be talking about these blasts over here, very close to the final surface, that are important in their detonation so as not to blow off important features like Crazy Horse's nose in the process of removing this rock. Let's first of all talk about rock reinforcement. Remember I said the importance of what isn't rock, and here we see some these features that aren't rock, these joints that form weaknesses in the rock. One of the difficulties with using explosives is that they produce enormous volumes of gas, and it's important to keep that gas from moving up these joints and separating the rock joints and degrading the rock to the point it's not useful. Here is the model in the sculptor's shop with these numbers on it here. These numbers define the locations of the reinforcing bars that are in Crazy Horse's nose. Here is a side or profile view. This is a frontal view of Crazy Horse's nose, here, the two nostrils, and these are the computer lines of the some 20 reinforcing rods that were placed in the nose. A hole was drilled, a rod was placed in the nose, and then grouted in place. And this is placed so as to ensure that even if some gas pressures were to have by some way leaked out into this rock, it wouldn't move the rock around and remove the nose. As you could imagine, fixing a 20-foot nose would be quite an arduous task in this particular environment. ------------------------------------------------------------------------------------------ 50:18:00 ------------------------------------------------------------------------------------------ Now let's talk about the nose blast, which is probably one of the more interesting blasts that was conducted for finishing the face. Now, if you think about it, there are three dimensions in any volume, so I'm going to talk about all three dimensions here, as we go through this. The first, most important thing, is to cut this channel at the top with the torch. This channel was some 6 inches thick, went 3-1/2 feet into the rock, and was some 21 feet long. So, basically, the rock was melted to produce a pathway for any of the delayed gases to be blown out here rather than be blown up into the rock. Secondly, then, parallel holes were drilled parallel to the 20-foot dimension. They were 6 inches apart in this orientation, and they were drilled from 30 feet high in this particular blast. The holes, then, were loaded with only 50-grain detonating cords. There's only 57-thousandths of a pound of explosive per foot that was put in each of these holes. And the holes were filled with silica sand to prevent the plastic from being blown into the remaining rock and discoloring it. It turns out that that was a very important part of this project, that the plastic would turn black upon explosion, and it would be blown into the rock and would discolor it, so that was an important thing. These holes were then detonated in 4 rows each with 9-millisecond intervals. Here is a photograph of that particular blast. Here is the blast and then here is the rock, then, that results afterwards. And I have to share with you here not this blast, but another blast, so you get to have some idea of what this experience is like. So, Let's see if I squish the two screens Hopefully, I was sufficiently trained for this, and I push this button ... 10-9-8-7-6-5-4-3-2-1 Fire in the hole, fire in the hole, fire in the hole. [Now how do I stop it?] Push that. All right, so you can see that it's a quite energetic event. The photographs really don't display the energy that's released upon explosion. I think it's quite remarkable that, given the amount of energy involved in the explosion, that in fact it's being able to be controlled. such precision to allow it to be used so close to such a precarious part of the carving. Now, we get to the final 6 inches of very, very fine detail, for instance, eyebrows, holes for the iris in the eye, lips, and things like this. We're back to the old way it always was done, and that is drilling holes and putting wedges in every other hole, and splitting the rock in between the holes and wedges. So that's what's begin done here -- drilling the holes for the final wedging process. That, then, produces the final surface that you see here, which then needs to be smoothed off to produce this smoothness. And that final surface was then produced by this torch. This is a jet-fueled torch that produces temperatures on the order of 2,000 degrees Centigrade. For those of you who are geologists, you know that rock melts at around 1200 degrees Centigrade, so this is a very hot flame. The fellows who worked on the mountain said they preferred to do this in the winter rather than in the summer. It was a lot cooler then. They had to wear flame-proof clothing because of the small particles of rock that might pop off. And the way the process basically works, in addition to being able to melt the rock sufficiently if the torch were ever held in one position for long enough, if you think about it, this granite is composed of minerals that have relatively large differences in coefficients of thermal expansion. And, so, when they're heated rapidly, they expand at different rates and basically flake off. So, in a way, you can take advantage of two smoothing mechanisms -- melting and flaking of the minerals due to different rates of thermal expansion. All right, so that completes the first three learning styles, and now we have sort of the what-if questions, for those of you who like to ask what-if questions. And I thought I would concentrate, on that portion of the lecture, with a comparison with Mount Rushmore, because I think that's probably in your minds, Well, how does this compare with Mount Rushmore? And it's the first observation I like to make -- so far there has not been a movie made at Crazy Horse, that I know of, anyway. You all remember North by Northwest with Cary Grant. I don't think that they actually ran around on Mount Rushmore itself, because I don't think there's really a place that you could do this safely on Mount Rushmore, so they probably did this on a set in Hollywood somewhere. One of the other interesting comparisons is the fact that they are only 18 miles apart in the State of South Dakota. Here's Crazy Horse, and here is Mount Rushmore, and they're very, very close, so if you do one, you should do them both. Another very important distinction that is made is the fact that Mount Rushmore is carved basically out of a white-hued granite, whereas Crazy Horse is carved out of a granite pigmatite that's relatively pinkish in hue, so therefore, the hues of the color of the two monuments, in fact, reflect the differences in ethnicity and I think was one of the basic reasons why Thunderhead Mountain was chosen for this particular site. In addition to its geometry, it also had the color that seemed to be most appropriate for the Crazy Horse carving. Some things haven't changed. This is a comparison of the drilling platforms that were employed for carving at Mount Rushmore and the same type of drilling platforms are employed here for Crazy Horse. The most important qualification to work on the mountain at either Crazy Horse or Mount Rushmore, I'm told, was a skill in mountain climbing. Not that you knew how to blast, but you had to be a good mountain climber, so that you would feel very comfortable being held by a rope while dangling on a face like this working hard and long. I'm told that one of the tests that was employed for Mount Rushmore, sometime during the first week that you were in this particular basket here, they'd drop the basket about a foot while you were working, and see whether or not you came back the next day. If you came back the next day, you obviously were able to withstand a certain amount of anxiety and were relatively cool under certain circumstances That, I think, is really one of the more interesting observations of now difficult this work really is. This is not easy work. Some of the technology has improved somewhat over that that was used. Rather than use someone's body as a reaction for the drill, as was done in Mount Rushmore, the folks at Crazy Horse tie the drills into the rock face and basically winch the drills in using the rock as a reaction force as opposed to the body. It's a lot easier and doesn't wear the driller out quite as fast. Now, there's a relative difference in the explosives that were used. Mount Rushmore was carved and excavated during the age of TNT, and this is a photograph of some of the workers on Mount Rushmore, whereas Crazy Horse was excavated and fragmented in the age of ammonium nitrate fuel oil. Ammonium nitrate fuel oil, it's development lowered the price of explosives at least an order of magnitude if not somewhat more than that, so it let to a a wide, rapidly adopted extra use of explosive. One other interesting part here -- you see each of these little pieces of TNT with a line running out of it? They did not have a way at that time to distribute explosives along the hole that the folks at Crazy Horse do now, with detonating cord. so they basically had to produce little pieces of explosive like this out of the TNT and put a blasting cap in it. Now, one of the challenges of a job like this is, if you work with nitrates it gets absorbed into your skin and it causes a huge nitrogen headache. You can imagine the people who were cutting TNT like this and what kind of a headache they'd have after working with this job for a while. So, it was quite a different environment for the carving of Mount Rushmore than the carving of Crazy Horse. To describe the difference of environment, I ran across this chart, here, of millions of pounds of explosives produced in the United States versus time. Basically, we look at the top curve, which is the sum of all the other curves below. The two red bars define the dates during which the Crazy Horse, I mean, the Mount Rushmore was carved, basically started in 1927, finished around 1941. This is the Depression. Notice the dramatic dropoff in the use of explosives. That, in a sense, describes the dramatic dropoff in industrial production over the world. Notice also that during the time over which Crazy Horse has been carved, the dramatic rise in the use of explosives, and that's a result of the discovery of ammonium nitrate fuel oil. ------------------------------------------------------------------------------------------ 01:00:41 ------------------------------------------------------------------------------------------ For those of you who don't know, ammonium nitrate fuel oil wasn't discovered until the late 1940s when two fertilizer ships blew up, one in Houston, Galveston Harbor and one in Brest, France. These fertilizer ships were filled with bagged of ammonium nitrate prills, and ammonium nitrate prills are sphericals of ammonium nitrate that are produced by dropping liquid ammonium nitrate down a tower. And these prills were developed as an efficient way of distributing ammonium nitrate for agriculture purposes. It turned out that the prilling of the ammonium nitrate produced a little ball that had just the right permeability to absorb amounts of carbon and fuel oil that would be necessary to supply the extra oxygen and carbon for the most efficient chemical reaction. And what happened was, these two ships were sitting there completely loaded with this ammonium nitrate, and the carbon from the bags in which they were stored was sufficient in order to to provide the extra chemicals that were necessary for the complete oxidation for the explosive reaction. So, it's kind of interesting how these accidents actually propelled the development of this technology. And I'd like to close with this, for you to remember, that this is being built so that the legends never die, and the dreams never end, and there always will be greatness. Thank you very much for your attention. [Applause] [Edil] I think we can take a couple questions from the audience, if you have questions. [audience member] When will they finish? [Dowding] Sure. I think you've got it just about right, Craig. They've been at this for over 50 years now. They're probably maybe a third of the way done. This is sort of similar to building a cathedral, I think. That basically, if you think about this as Washington National Cathedral. That's still isn't done yet. Part of the excitement of this is watching it being constructed. There are a number of people when I've given this lecture before, have talked about being taken there by their grandfather and what not a number of years ago, and describing the history of their family's involvement in this. As I said before, their funding is relatively user and visitor supplied. Basically, that is the major source of funding. It's interesting, there are 180 people down below here. In your brochure there's a description and a photograph of the gift shop and the visitors' center facilities. And there are only about 12 to 18 people on the mountain blasting. It's sort of like the military. >From what I understand, it takes 10 people in the Pentagon to put one person in the field. Well, that's about the right ratio. And the Pentagon, of course, has Congress raising money for them. So they have even more work to do here. And it's my impression that it would take another 50 years to basically finish down to here, maybe. Maybe 75. And, I'm not sure they're ever going to this. Because the rock goes way out here. In order to remove it there's a huge amount of excavation that needs to e done here. That's a pretty tall order. Very good question. [Edil -- Any other question?] [audience member] [unintelligible] [Dowding] Gee, that was a real nice question to ask a geotechnical engineer. Yes, have you ever heard of the author John McPhee? There's a book, In Control of Nature, and John McPhee describes the cycle of chaos in California. And, basically, what happens, there's drought, and then there's a fire, and the fire kills off all the brush that stabilizes the slopes, and then there's rain, and the rains come and destabilize the slopes, and basically the mountains slide down into the stream valley. So, your premonition is exactly true. All of those areas that were denuded of all of that vegetation, that have now been separated from the stabilizing benefits of that vegetation, now have much lower factors of safety, will not be moving down, will most assuredly be moving downhill. The question is just, Exactly where will that will happen? It's big environmental impact. Yes? [audience member] ...environmental impacts of ammonium nitrate fuel oil? [Dowding] Well, I'd say, of the explosives, given the fact that this is basically an agricultural fertilizer product, that of all the explosives, this would probably have the least environmental impact of any of the explosives. It's a good question, though. It's an interesting thing to think about. Yes. Is there a question over here? Accidents? Not that I've been told of. You know, I don't know level what you mean by accidents. I don't think there have been any fatalities on this particular project. It's a good question. It is somewhat dangerous, isn't it? Yes. Well, I think you're beginning to noodle in on the difference between art and engineering. This is predominantly an artistic endeavor It was started by someone who was, I'd have to say, extremely visionary, and more of an artist than an engineer. As a result of that, basically, I would make the analogy, It's sort of like someone jumping off a cliff and manufacturing a parachute on the way down. I mean, this is a project that was very long on vision, very long on chutzpah, and, perhaps, very short on engineering calculation. But that's a really good question, because, as this project develops, as you pointed out. there are some very, very delicate features on this particular carving that require some very careful calculation and some very careful and meticulous engineering that will need to go into this. And as the project develops, you know, more and more sophisticated rock mechanics and engineering will need to be applied to this to ensure that it can in fact be completed. Very good question. Yes? [audience member] ...accidents at Crazy Horse? [Dowding] You know, I really couldn't estimate, except to go back to the fact that there are, think of this, there are 180 people down at the visitors' center, basically changing all that visitor interest into resources that can be used to carve the rock out of the mountain. So, basically, if you think that there might be 40, 50 thousand people a year that then generate $9 apiece for a visitors' fee, you run that money into your cash flow. They are about to go out for a fund raising, you know, a 10-, 20-million fund raising effort in order to raise money. Most of the industry now has sort of come to see this as a very, very important symbolic kind of endeavor, and many components of the blasting industry are donating large amounts of money to the project, so all that gets ground in. But the cost of doing something like this, I mean, if you think about doing anything over a 150-year span, it would have to be in the hundreds of millions of dollars. At least that. It's a very, very expensive project. Interesting question. There are several others here. Yes. [Tuncer Edil] One last question, yes, go ahead. [Dowding] What are they doing with all the rock they blast off? Currently, the rock is basically all down at the bottom right now, and they are going to be using it for the ramps to come up from the bottom. That question brings up kind of an interesting issue. This is an artistic project. This is not a commercial project, so they're not selling the rock. And, they basically can't sell the rock, because if they were it would be a commercial project and it wouldn't be art, and it would then be regulated by OSHA, and you can imagine how difficult it would be to finish that face off if you couldn't rapel down on a rope. [Tuncil Edil] On that note, we will close. Thank you for listening to a very interesting lecture. [Dowding] Thank you very much. ------------------------------------------------------------------------------------------ 01:11:01 ------------------------------------------------------------------------------------------ Reference: http://www.crazyhorse.org/ Created 13-Dec-2004. Last updated 13-Dec-2004.