Roadway Cratering Research - National Defense Industrial ...proceedings.ndia.org/3500/Rickman_Demo_NDIA.pdf · Roadway Cratering Research US Army Corps of Engineers Engineer Research

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



Roadway Cratering

ObjectiveEvaluate current roadway cratering methodologies and investigate improved methods/materiel.



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



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)



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



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.



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



Roadway CrateringSample Roadway Craters – 50-lb Charges

50-lb C-4 Charge40-lb AN Charge + 10 lb C-4



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



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



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



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



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



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



Roadway CrateringCrater overview – PAM Test 5, 15-degrees off vertical

1 ft

Painted crack-lines



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



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

Documents

Roadway Cratering Research - National Defense Industrial ...proceedings.ndia.org/3500/Rickman_Demo_NDIA.pdf · Roadway Cratering Research US Army Corps of Engineers Engineer Research