CRTI-06-0252RDProtocols for Modeling Explosive Threats in Urban Environments

R.C. Ripley, F. Zhang, D. Whitehouse, L. Donahue,K. Scherbatiuk, F.-S. Lien, P. Caron

CRTI Summer Symposium 2009, 15-16 June, Ottawa

Project Team

• Public Safety Canada (Lead Dept.):– Pierre Caron (PM), Tim Patraboy (DPM), Glenn Flood

• DRDC Suffield:– Fan Zhang (SA), Kevin Scherbatiuk (Structural)

• Martec Limited:– David Whitehouse (Protocols), Robert Ripley (Models & UE

Solutions), Laura Donahue, Eric Li (PV), Tim Dunbar (SV)• University of Waterloo:

– Prof. Fue-Sang Lien (Models), T. Xu, H. Ji• RCMP:

– Sgt. J.-Y. Vermette

Introduction

• Modeling is a key tool to support analysis of terrorist explosive threat impact on Canadian urban targets

• Need reliable approaches for generating and delivering information to decision makers

Blast Interaction Regimes

Suffield Scaled Urban StreetUnconfined Free-Field Blast

Urban Street Explosion

High Confinement

Train StationSubway

TunnelParkade

Simple Models are Not Always Sufficient

Oklahoma City (1995)

Moscow (1998)

Risk Management Series FEMA 426 (2003)

Urban Blast Modeling

High-fidelity, first-principles model

Capability and Knowledge Gaps

1. Fast and approximate modeling tools do not properly address near-field scenarios found in urban environments

2. Lack of physical models for non-ideal explosives in close proximity to urban structures

3. Lack of supporting documentation and corresponding guidelines for effective use of modeling tools

Objective of CRTI-06-0252RD

To develop protocols serving as standards and guidelines for modeling both ideal and non-ideal

explosive threats in close proximity to urban structures and environments

What are the Blast Modeling Protocols?

• Guidelines to be followed when performing/evaluating blast analyses for threats in urban environments

• A series of sequential steps which cover the blast analysis process

• Consider best-practice modeling while not restricting analyses to specific approaches

• A key feature is a set of baseline urban test cases – Database of accurate pre-computed urban scenarios

for quick analyses– Used to evaluate the range of applicability of any

blast modeling approach for a specific urban blast event

Project Roadmap

Eight Protocols Steps

Define and Interpret

Pre-Calculation Guidance

Calculation Steps

Analyze and Summarize

Who are the Protocols Users?

• Performers – Focus on performing and delivering results from a

specified blast analysis

• Consumers – Understand the context of blast problem which needs

to be solved– Provide advice to outside groups– Manage the resources on projects addressing security

issues, which may include the blast analysis

• Decision Makers – Take action based on the analysis results– Interested in how protocols reduce their risk

Pre-Calculated Scenario Matrix

• A total of 300 scenarios are planned

• Include range of targets and threats

Fundamental Urban Elements

U1: Straight Street

U3: Urban Bay U4: Urban Corner

U2: Single Building U5: Street Intersection

U6: Alley Intersection

Structural Elements

Classes of Explosives (Tentative)

1. HE (C4, TNT)2. Energetic Liquids (TATP etc.)3. Slurries (ANFO)4. Energetic Liquid/Metal Particles (NM/Al, Mg, Ti, Zr)5. Aluminized AN6. Organic Powder – Based Mixes (Corn Starch)7. Granular Explosive (pipe bombs)8. FAE (Liquid HC Fuel into Air)

Coordinated with CRTI-06-0204RD ‘Improvised Explosive Assessment’ and CRTI-07-0153RD ‘Transport of Combustible Liquids’

Preliminary User Survey Results

Type Rating (5 high)

ANFO 5.0

TNT 4.8

AN+other 4.8

Liquid Hydrocarbon 3.9

Liquid (NM, IPN) 3.3

Aluminized 3.1

TATP 3.0

Additional user surveys planned within the CRTI community

Description Rating (5 high)

4-Way Street Intersection 4.7

Parkade (small and large) 4.7

Straight Street 4

Internal Blast 3.8

Side-Street Alley 3.7

Urban Bay 3.6

Bridge Underpass 3.5

Tunnel Entrance 3.4

Single Building Façade 3.2

Bridge Tunnel 3.2

Blast Threats

Urban Environments

Blast Enhancement Table

# Walls 1 2 2 3 … 4 5 6

Elements →Free-Field

Single Building

Parkade Street … TunnelCourtyard/

MarketInterior RoomThreats ↓

TNT 1.0 6.0 10.0 11.0

C4 1.2 7.2 11.5 12.0

ANFO 0.8 4.5 7.8 8.4

Aluminized Explosive

1.5

FAE 10.0

…

Blast Enhancement Table

# Walls 1 2 2 3 … 4 5 6

Elements →Free-Field

Single Building

Parkade Street … TunnelCourtyard/

MarketInterior RoomThreats ↓

TNT 1.0 6.0 10.0 11.0

C4 1.2 7.2 11.5 12.0

ANFO 0.8 4.5 7.8 8.4

Aluminized Explosive

1.5

FAE 10.0

…

Physical Models

Required for simulating detonation and near-field blast from classes of conventional and non-ideal explosive threats, and their interaction with confined urban environments

Confined Explosive Afterburning

t = 5.7 ms

t = 10.7 ms

t = 20.7 ms

t = 50.7 ms

Donor Chamber

Acceptor Chamber

Confined Explosive Afterburning

Ea=120 kJ/mol

Ea=71 kJ/mol

Micrograph of particles

Unconfined Detonation

DDT process in a closed tube

Abrupt DDT

Aluminum Detonation in Air

Non-Ideal Explosive Analysis

Dense Multiphase Flow Mixing Models

• Particle jetting / wake and boundary layer interaction

pFr

, (drag)p xF

, (lift)p yF

D.L. Frost, MABS 19

Status and Plan

• FY08-09

– Physical models implemented (Del #3 and 4)

– Protocol prototype design complete (Del #5)

– First user meeting completed (users and scenarios)

• FY09-10

– Physical models validation underway

– Scenario calculations to begin after matrix finalization

– Protocol platform selection under review

– Additional user feedback meetings

– Protocol process requires testing and design iteration

• Final Protocols ~ June 2011

Questions?

Vulnerability Guidelines

FE M (low res) D E M S D O FS o/L

0.1 (near fie ld )

1 (m id fie ld )

10 (fa r fie ld )

h igh res FE M orana lytica l (perfect

so lu tion , assum e noerror)

%error

%error

%error

%error

err

or

tole

ran

ce

S o /L S o/L S o/L S o/L

valid

ra

ng

e

valid

ra

ng

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valid

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Combined Human Injury Chart

lines o

f equal td

upper range(destructive

timings)

lower range(constructive timings)

Structural Response for Non-Uniform and Complex Blast

Particle FragmentationDetonation Fragmentation

Impact Fragmentation

Reflection

Thermal Cracking

Aerodynamic Fragmentation

Wall Coating

Protocols Steps – Top Level

• There are 8 steps for performing blast analyses:

• Attributes

– Sequential

– Modular

– Reproducible

– Auditable

Define and Interpret

Pre-Calculation Guidance

Calculation Steps

Analyze and Summarize

Protocols Steps – Process Details