View
4
Download
0
Category
Preview:
Citation preview
Roadway Cratering Research
US Army Corpsof Engineers
Engineer Research and Development Center
Presented by
Denis Rickman
Impact & Explosion Effects Branch, GSLEngineer Research & Development Center, Vicksburg, MS
US Army Corpsof Engineers
Engineer Research and Development Center
Roadway Cratering
ObjectiveEvaluate current roadway cratering methodologies and investigate improved methods/materiel.
US Army Corpsof Engineers
Engineer Research and Development Center
Roadway Cratering
Approach• Coordinate research effort with MANSCEN/Picatinny Arsenal
• Evaluate effectiveness of current demolition methods (FM-250) for producing roadway craters
• Perform tests of the PAM as a potential roadway cratering munition
• Evaluate alternative methods/explosives for use in roadway cratering to determine whether methods requiring less explosive are feasible
• Report results to MANSCEN/Picatinny
US Army Corpsof Engineers
Engineer Research and Development Center
Roadway CrateringEvaluation of Cratering Explosives
Purpose: Evaluate cratering effectiveness of various explosives in precise boreholes (with tamping) as a baseline for further studies of improved cratering methods
40-lbAN charge
TNT powder
C-4
Binex 400(Sodiumperchlorate/aluminum)
US Army Corpsof Engineers
Engineer Research and Development Center
Roadway CrateringEvaluation of Cratering Explosives
Plan View
Cross-Section
Borehole Asphalt
50-lb TNT40-lb Cratering Charge + 10 lb C-4
50-lb BinexSlurry
50-lb BinexSlurry
150 ft
30 ft 15 ft30 ft30 ft 30 ft15 ft
24 ft
5 ft
Shaped Charge
40-lb Shaped Charge
Tamped Soil
50-lb C-4Hole From Shaped Charge
US Army Corpsof Engineers
Engineer Research and Development Center
Roadway CrateringEvaluation of Borehole Effects and Pavement on Cratering
Investigate:
1. Cratering efficiency of charges placed in a shaped-charge created hole
2. Effect of leaving borehole untamped3. Effect of pavement/no pavement
Purpose: Evaluate effect of borehole shape/tamping and the presence of pavement on cratering efficiency. Use 50 lb of C-4 as the explosive charge.
US Army Corpsof Engineers
Engineer Research and Development Center
Roadway Cratering
Plan View
Cross-Section
Asphalt
Base CourseBase CourseCompacted Compacted Native SoilNative Soil
50-lb C-4 Charge
Asphalt
Base CourseBase Course
UntampedTamped Soil
Evaluation of Cratering Explosives – Baseline Study
24 ft
60 ft
30 ft
Base CourseBase Course
15 ft15 ft15 ft 15 ft
5 ftAsphaltAsphalt
50-lb C-4 Charge
Tamped Soil
US Army Corpsof Engineers
Engineer Research and Development Center
Roadway CrateringSample Roadway Craters – 50-lb Charges
50-lb C-4 Charge40-lb AN Charge + 10 lb C-4
US Army Corpsof Engineers
Engineer Research and Development Center
Roadway CrateringRoadway Craters – Tamped 50-lb ChargesAN/C-4/Binex Comparison
Distance, ft
Net c
hang
e in
ele
vatio
n, ft
-5 0 5 10 15 20 25 30 35-5
-4
-3
-2
-1
0
1
2
3
4
5
Shot 2 - 40 lb AN + 10 lb C-4 tampedShot 4 - 50-lb C-4 tampedShot 8 - 50 lb Binex - tamped
Shot 2 vol. = 316.8 ft^3
Shot 4 vol. = 275.8 ft^3
Shot 8 vol. = 487.5 ft^3
US Army Corpsof Engineers
Engineer Research and Development Center
Roadway CrateringRoadway Craters – Tamped 50-lb C-4 ChargesAsphalt Overlay vs. Soil
Distance, ft
Net c
hang
e in
ele
vatio
n, ft
-5 0 5 10 15 20 25 30 35-7
-6
-5
-4
-3
-2
-1
0
1
2
3 50 lb C-4 CONWEP asphalt ovr dry/moist50 lb C-4 CONWEP dry sandy clayShot 4 - 50-lb C-4 tamped, asphaltShot 6 - 50-lb C-4 tamped, base coarse
US Army Corpsof Engineers
Engineer Research and Development Center
Roadway Cratering
Based upon the results, the following observations were made:
• Roadway crater size appears to be unaffected by asphalt cover
• CONWEP currently predicts larger craters for asphalt cover than for bare soil; this needs to be corrected
• The 40-lb AN cratering charge performs well relative to C-4 and TNT
• The best cratering explosive evaluated was Binex 400
• Binex crater volume was >50% larger than that for AN and >75% larger than for C-4
• Binex may be of interest as a COTS item for demolitions
US Army Corpsof Engineers
Engineer Research and Development Center
Roadway CrateringPAM (Penetration-Augmented Munition) Evaluation
PAM Physical Characteristics:Weight: 35 lbLength: 33 in.Diameter: 8 in.Target: Reinforced concrete bridge supportsAttachment: Silent stud driverInitiation: Blasting cap, detonation cord, or any standard military detonation devicePerformance: Single-shot defeat of 5 ft x 6 ft reinforced concrete pierDefeat mechanism: Shaped charge, hole-drilling charge, and follow-through warhead (4.7 lb LX-19)Shipping container: TOW 2A container
Purpose: Work with USAES/MANSCEN and Picatinny Arsenal to evaluate the PAM (XM-150) as a one-step roadway cratering tool
US Army Corpsof Engineers
Engineer Research and Development Center
Roadway CrateringPAM Evaluation
PAM cratering effectiveness tests – Plan View
Single PAM
Base CourseBase CourseAsphaltAsphalt
Compacted Compacted Native SoilNative Soil
Single PAM
PAM cratering effectiveness tests – Cross-section
10 ft 16 ft 16 ft 16 ft 16 ft 16 ft 10 ft16 ft
100 ft
US Army Corpsof Engineers
Engineer Research and Development Center
Roadway CrateringResults Overview
• The PAMs produced camouflet-type craters in which a hollowed-out area extended beyond the hole cut through the roadway surface
• Vertically-oriented PAMs caused little or no local heaving of the roadway; PAMs inclined at 15-30° off vertical caused more pronounced roadway heaving and cracking
US Army Corpsof Engineers
Engineer Research and Development Center
Roadway CrateringCrater overview – PAM Test 5, 15-degrees off vertical
1 ft
Painted crack-lines
US Army Corpsof Engineers
Engineer Research and Development Center
Roadway Cratering
Distance, ft
Net
cha
nge
in e
leva
tion,
ft
0 2.5 5 7.5 10 12.5 15 17.5 20-5.4
-4.8
-4.2
-3.6
-3
-2.4
-1.8
-1.2
-0.6
0
0.6Distance, ft
Net
cha
nge
in e
leva
tion,
ft
17.5 20 22.5 25 27.5 30 32.5 35 37.5-5.6
-4.8
-4
-3.2
-2.4
-1.6
-0.8
0
0.8
1.6
2.4Excavated crater profiles – PAM test 5, 15-degree inclination
Subgrade
Asphalt
Asphalt
Subgrade
Profile along roadway centerline
Profile across roadway
PAM orientation
PAM orientation
US Army Corpsof Engineers
Engineer Research and Development Center
Roadway Cratering
Based upon the results, the following observations were made:
• The PAM appears to have potential for development as a roadway or runway cratering tool
• A larger follow-through charge is needed to produce fully excavated craters.
• Based upon the depth of the follow-on charges (~4 ft) at detonation, CONWEP calculations show that it is likely that the charge size will have to be at least doubled (from 4.2 lb to 8.4 lb+) to maximize the crater volume produced
Summary-PAM
Recommended