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Engineers Without Borders, Duke University Chapter Bolivia – Bridge in the Obrajes Valley Cone Penetrometer Data Notes on Device Usage We used a doughnut hammer cone penetrometer for our tests, which was slightly deformed – a noticeable bend in the drill shaft at the joint to the drop shaft. We will calibrate the machine back at Duke and adjust the raw data presented here accordingly. Some tests were performed by Thomas Grothe – his data may be read at follows. Starting depth (SD) is the depth of the initial hole dug. Sink is the distance the cone penetrometer penetrates simply under its resting weight. Thereafter, N# denotes the total number of blows required to reach # inches past the sink depth. Total depth (TD) is the final distance of the cone penetrometer´s tip from the surface. (Example: SD = 6”, Sink = 2”, and largest N at 18” implies TD = 26”). The tests performed by Matt Ball are identical except for analysis of sink. In his tests, for N#, # includes the sink depth. (Example: SD = 6”, Sink = 2”, and largest N at 18” implies TD = 24”). Notes on Data Presentation All depth measurements are in inches. N# refers to the number of blows required to penetrate # inches, varied by operator as described in “Notes on Device Usage.” The final column in each data table is blank unless 18” drill were not reached, in which case it supplies a third value of N$, where $ is the depth drilled by 100 blows or another useful point. . On-site pictures will accompany this report when available, and will be labeled “CPT (Crossing Name) (Picture Description).” Iruma Crossing 1 Test Location: River, middle Operator: Thomas Grother Description: Dry soil, pebbly with small rocks. Mainly sand with some earth. SD Sink N6 N12 N18 TD 6 1 11 34 80 25 Notes: No groundwater or mud even at maximal depth. Progress slowed noticeably after 15”, 50 blows. Probably struck a rock, based on change in penetrometer vibrations. 2 Test Location: River, middle, five feet from Iruma 1 Operator: Thomas Grothe Description: Deeper starting hole found fewer significant rocks, and firmer/clammier soil. SD Sink N6 N12 N18 TD 24 1.5 9 22 36 43.5 Notes: Very soft soil – bottom 13” of drill shaft were also muddy. Softness of nearby ground implies further that Iruma 1 hit a rock. 3 Test Location: Bank, close to waterline Operator: Thomas Grothe Description: 3” of fine sand cover a firmer clayish brown soil. Equal mass of pebbles and soil. SD Sink N6 N12 N18 TD N9 6 1.5 38 120 NA 19.5 85 Notes: Very hard sandy soil, firmly compacted. 4 Test Location: River, middle, 40´ downstream of the road Operator: Matt Ball Description: Moist soil. Site appears to be within river´s natural course. SD Sink N6 N12 N18 TD 6 1.5 4 13 30 24 5 Test Location: River, middle, 4´ from Iruma 4 Operator: Matt Ball Description: Same as Iruma 4 SD Sink N6 N12 6 1.5 7 19 N18 28 TD 24 6 Test Location: River, middle, 4´ from Iruma 5 Operator: Matt Ball Description: Same as Iruma 4 SD Sink N6 N12 6 1.5 3 9 N18 20 TD 24 Notes: Iruma 5/6 straddle the second road crossing. 7 Test Location: River, in line with Iruma 4-6 Operator: Matt Ball Description: Sandier soil than Iruma 4-6 SD Sink N6 N12 6 1.5 3 8 N18 12 8 Test Location: River, near Iruma 7 Operator: Matt Ball Description: Same as Iruma 7 SD Sink N6 N12 N18 6 1 13 24 43 nd Notes: Nearly in line with the 2 surveying cross-section. TD 24 TD 24 Jachuma 1 Test Location: River, middle Operator: Thomas Grothe Description: Sandy, browner and more earthy 3” down. Pebbles, small rocks. Slightly clammy. SD Sink N6 N12 N18 TD 6 1 17 49 88 25 Notes: Few large rocks beneath surface. Muddy for the last 7”. 2 Test Location: River, middle, near Jachuma 1 Operator: Thomas Grothe Description: Same as Jachuma 1, but muddy. SD Sink N6 N12 N18 24 0.5 20 50 77 Notes: Slightly muddy as stated, but still no groundswater. 3 Test Location: River, closer to bank Operator: Thomas Grothe Description: Same as Jachuma 1 SD Sink N6 6 1.5 21 Notes: 7” mud. N12 41 N18 59 TD 42.5 TD 25.5 4 Test Location: River, close to bank Operator: Thomas Grothe Description: Rockier than Jachuma 1, but still mostly pebble-sized rocks. SD Sink N6 N12 N18 TD 7 3 25 42 53 28 Notes: 13.5” mud. 5 Test Location: Bank,near the road Operator: Thomas Grothe Description: Packed sand-earth, some thin roots, clayish earth after 4”. Very compact. SD Sink N6 N12 N18 TD N7.5 6 1 73 NA NA 14.5 100 Notes: Extremely compact and dry. Probably compressed because so near to road. 6 Test Location: Bank, opposite of Jachuma 5 Operator: Thomas Grothe Description: Rocky and dry, not as packed as Jachuma 5. SD Sink N6 N12 N18 TD 27 1 16 68 NA 45 Notes: Felt more like firm earth than hitting a rock. 1.5” slight mud. N16 100 Condor Chinoka 1 Test Location: River, shallow section near road Operator: Thomas Grothe Description: Sandy/pebbly surface, near paja plants. SD Sink N6 N12 8 1 68 NA Notes: No mud. Might have hit a rock. N18 NA TD 16.5 N7.5 100 2 Test Location: River, near Condor Chinoka 1 Operator: Thomas Grothe Description: Same as Condor Chinoka 1. SD Sink N6 N12 N18 TD N2 6 0.5 NA NA NA 8.5 47 Notes: Hit large, immovable rock. Attempted to dig past that layer for another test at the same spot, but proved futile. There are no more tests from Condor Chinoka – the site consists of many layers of rock; uncertain of how far to actual bedrock, but it shouldn´t be more than 1.5 meters. Digging past each layer only ever revealed another layer of rock, and the drill could never pass a few inches successfully. It´s also impossible to drill on the bank – one can clearly see the layers of rock at the cliff. Obrajes I (Hot Springs River) 25/5/2008 1:15PM 1 Test Location: River, middle Operator: Matt Ball Description: Wet, pebbly soil. Occasionally large (12”) rocks. SD Sink N6 N12 N18 6 1.5 19 84 NA Notes: Groundwater at 6”. 2 Test Location: River, middle, near Obrajes I 1 Operator: Matt Ball Description: Same as Obrajes I 1 SD Sink N6 N12 6 3 11 64 Notes: Groundwater at 5”. 3 Test Location: River, middle, near Obrajes, I 2 Operator: Matt Ball Description: Same as Obrajes I 1 SD Sink N6 N12 6 3 7 51 Notes: Groundwater at 3”. 4 Test Location: Bank Operator: Matt Ball Description: Dry, sandy bank. SD Sink N6 N12 6 0.5 10 38 Notes: Lost count, repeated in Obrajes I 5 5 Test Location: Bank Operator: Matt Ball Description: Same as Obrajes I 4 SD Sink N6 6 0.5 24 N12 42 6 Test Location: Riverbed Operator: Matt Ball Description: Moist Soil, some small rocks. . SD Sink N6 N12 6 1 23 63 Notes: No groundwater. TD 19.5 N13.5 100 N18 NA TD 22 N16 100 N18 97 TD 24 N18 Errrr... TD 24 N18 60 TD 24 N18 NA TD 22 N16 100 7 Test Location: Riverbed, near Obrajes I 6 Operator: Matt Ball Description: Same as Obrajes I 6 SD Sink N6 N12 6 2 18 NA Notes: Groundwater 8” below surface. N18 NA TD 17 N11 100 Obrajes II (Rio Imura) Sites notes: The riverbed consists entirely of sheet rock – drilling is futile. Instead, the depth of the mud covering said sheet rock was measured all over the crossing area. Find attached an aerial view of the crossing with sand/mud depths marked. 1 7 Test Location: Bank by road, nearer to Obrajes Operator: Thomas Grothe Description: Packed sand, nearly sandstone. Some paja grass. Unable to dig significantly with shovel. SD Sink N6 N12 N18 TD 0 0.25 98 NA NA 6.3 N6.05 100 8 Test Location: Bank by road, further from Obrajes Operator: Thomas Grothe Description: Looser sand covering the same sandstone as Obrajes 1. Paja grass surrounding. SD Sink N6 N12 N18 TD N14 6 1 19 71 NA 21 100 Notes: Hit same sandstone by 11” drill (18” total depth). This compressed (bank) sand is strong in compression but chips and crumbles easily.
