Roadway Cratering Research

Transcription

1 Research Presented by Denis Rickman Impact & Explosion Effects Branch, GSL Engineer Research & Development Center, Vicksburg, MS

2 Objective Evaluate current roadway cratering methodologies and investigate improved methods/materiel.

3 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

4 Evaluation 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-lb AN charge C-4 TNT powder Binex 400 (Sodium perchlorate/ aluminum)

5 Evaluation of Cratering Explosives Plan View 24 ft Shaped Charge 15 ft Borehole Asphalt 30 ft 30 ft 30 ft 30 ft 15 ft 40-lb Shaped Charge Tamped Soil 150 ft Cross-Section 5 ft Hole From Shaped Charge 50-lb C-4 50-lb Binex Slurry 50-lb Binex Slurry 40-lb Cratering Charge + 10 lb C-4 50-lb TNT

6 Evaluation of Borehole Effects and Pavement on Cratering 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. Investigate: 1. Cratering efficiency of charges placed in a shapedcharge created hole 2. Effect of leaving borehole untamped 3. Effect of pavement/no pavement

7 Evaluation of Cratering Explosives Baseline Study Plan View 24 ft Asphalt Base Course 30 ft 15 ft Asphalt 15 ft Base 15 ft Course 15 ft 60 ft Cross-Section 50-lb C-4 Charge Tamped Soil Untamped Asphalt Base Course Compacted Native Soil 50-lb C-4 Charge Tamped Soil 5 ft

8 Sample Roadway Craters 50-lb Charges 40-lb AN Charge + 10 lb C-4 50-lb C-4 Charge

9 5 Roadway Craters Tamped 50-lb Charges AN/C-4/Binex Comparison 4 3 Shot 2-40 lb AN + 10 lb C-4 tamped Shot 4-50-lb C-4 tamped Shot 8-50 lb Binex - tamped Net change in elevation, ft Shot 2 vol. = ft^ Shot 4 vol. = ft^3 Shot 8 vol. = ft^ Distance, ft

10 Roadway Craters Tamped 50-lb C-4 Charges Asphalt Overlay vs. Soil 3 50 lb C-4 CONWEP asphalt ovr dry/moist 50 lb C-4 CONWEP dry sandy clay 2 Shot 4-50-lb C-4 tamped, asphalt Shot 6-50-lb C-4 tamped, base coarse 1 Net change in elevation, ft Distance, ft

11 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

12 PAM (Penetration-Augmented Munition) Evaluation Purpose: Work with USAES/MANSCEN and Picatinny Arsenal to evaluate the PAM (XM-150) as a one-step roadway cratering tool PAM Physical Characteristics: Weight: 35 lb Length: 33 in. Diameter: 8 in. Target: Reinforced concrete bridge supports Attachment: Silent stud driver Initiation: Blasting cap, detonation cord, or any standard military detonation device Performance: Single-shot defeat of 5 ft x 6 ft reinforced concrete pier Defeat mechanism: Shaped charge, holedrilling charge, and follow-through warhead (4.7 lb LX-19) Shipping container: TOW 2A container

13 PAM Evaluation PAM cratering effectiveness tests Plan View Single PAM 16 ft 10 ft 16 ft 16 ft 16 ft 16 ft 16 ft 10 ft Single PAM 100 ft PAM cratering effectiveness tests Cross-section Asphalt Base Course Compacted Native Soil

14 Results 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 off vertical caused more pronounced roadway heaving and cracking

15 Crater overview PAM Test 5, 15-degrees off vertical Painted crack-lines 1 ft

16 Net change in elevation, ft Net change in elevation, ft Roadway Cratering Excavated crater profiles PAM test 5, 15-degree inclination Profile along roadway centerline Distance, ft Profile across roadway PAM orientation PAM orientation Asphalt Subgrade Asphalt Subgrade Distance, ft

17 Summary-PAM 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