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US Army Corps of Engineers
BUILDING STRONG®
Pavement & Geotechnical
Field Results Tribhuvan International Airport
Prepared by:
U.S. Army Corps of Engineers
09 July 2012
BUILDING STRONG®
Agenda
Problem
Statement
Background
Approach
Results
► Pavement
► Geotechnical
BUILDING STRONG®
Problem Statement
Due to a lack of information and limited record
keeping, TIA geotechnical subsurface details
and pavement condition and strength were
unknown.
► Without this information, details related to
liquefaction, water table levels, and slope stability
remained an assumption.
► The number of safe airfield operations remaining in
the runway surface was also unknown.
Geotechnical and pavement information is
needed to determine how an earthquake will
impact TIA operations and recovery.
BUILDING STRONG®
Background
In April 2011, a seismic vulnerability assessment was
performed for structural and airfield features at
Tribhuvan International Airport (TIA) in Kathmandu,
Nepal.
The assessment recommended numerous seismic
structural retrofitting measures, as well as a geotechnical
investigation and a pavement strength/condition test.
BUILDING STRONG®
S.
N Description
Vulnerability Priority Action to carry out
L M H 1st 2nd 3rd
1 Soil of North Side of Airport
Soil Investigation for potential of
liquefaction, Water Table Level & Slope
Stability.
2 Runway Pavement Assess runway pavement capacity &
existing condition
3 Drainage System Regular maintenance (remove plants &
soil)
4 Radar Tower Assessment of structural & operation
system
5 Radar equipment Building Structural assessment
6 Power House for Radar Structural assessment
7 Fuel Tank at Radar Compound Structural assessment
8 Fuel Pipe Replacement of rigid pipe to flexible pipe
at Junction
9 Rescue and Fire Fighting Building Structural assessment
10 Foam Store Building Structural assessment
Initial Top 10 Seismic Vulnerability
Recommendations
BUILDING STRONG®
Approach
Pavement: USACE partnered with
CAAN, TIA, USAF, and FAA to perform
a pavement strength and condition
survey in January 2012.
Geotechnical: USACE hired Multi
Lab, a geotechnical contractor, to drill
boreholes and perform analysis on the
soil samples collected.
BUILDING STRONG®
Pavement Testing Locations
BUILDING STRONG®
Pavement Testing Locations
BUILDING STRONG®
Pavement Results - Passes
Airfield pavement can withstand 100,000+
passes (dependent upon aircraft type) if
engineering and maintenance recommendations
are performed.
If engineering and
maintenance
recommendations are not
performed, the number of
passes reduces to
100 – 1,000.
BUILDING STRONG®
Pavement Results – AC Mixture
Asphalt composition and binder to aggregate
ratio varied greatly throughout the length of the
runway.
► Poor mix design or lack of materials during time of
batch plant production may be reason.
► The issue has led to large amounts of bleeding in
certain areas.
Results showed significant areas of subsurface
weakness on the north side of the domestic
apron.
BUILDING STRONG®
Pavement Results - Distresses
Pavement Condition Index (PCI) ratings ranged
between “Good” and “Satisfactory.”
Airfield surfaces have a number of common
distresses, which if not monitored and maintained,
could lead to severe operational issues.
Distresses included bleeding, fatigue cracking, block
cracking, corrugation, jet blast erosion, depression,
joint-reflection cracking, longitudinal/transverse
cracking, oil spillage, patching, weathering, rutting,
corner breakage, joint seal damage, pumping,
settlement, and spillage cracking.
BUILDING STRONG®
Pavement Results - Distresses
Bleeding
Cracking
Oil
Patching
Vegetation Joint Seals
BUILDING STRONG®
Pavement Results - Rubber
Rubber removal has also yet to be
accomplished on the main runway.
This equates to approximately three years of
build-up.
This build-up will lead to aircraft traction loss
during take-off and landing.
It is recommended that rubber removal be
accomplished within the next 12 months.
BUILDING STRONG®
Pavement Results – Other Concerns
Other pavement condition concerns includes:
► Rutting at the south end of the main taxiway.
► Low severity joint sealant damage in several
locations along the international apron.
► Fuel/oil spillage covering approximately 70% of
the domestic apron.
► Longitudinal cracking and potholes in several
apron locations.
► Inconsistent asphalt thickness (ex. ranges of 280-
380 mm from station 0+00 through 63+00, and
533-850 mm from 63+00 to 100+00.)
BUILDING STRONG®
Geotechnical Results - Overview
Ground investigation of the airport was carried
out by drilling 32 boreholes to varying depths of
4.5 m to 30 m.
Work performed
by a local
contractor
(Multi Lab) under
supervision of
USACE.
BUILDING STRONG®
Geotechnical
Results –
Priority Areas
During the seismic
vulnerability
assessment, this
map was produced to
indicate priority areas
for geotechnical
investigation.
BUILDING STRONG®
Geotechnical
Results –
Borehole Map
•32 boreholes
•Depths range from 4.5-
30 m
•Auger and percussion
main means of data
collection
•Collected 1/12 – 2/12
BUILDING STRONG®
BOREHOLE ELEV (M) DEPTH TO
WATER (M) DEPTH DRILLED
(M) START DATE END DATE METHOD LIQUEFACTION LIQ DEPTHS (M) TB-1 1314.92 17.0 30.0 2/4/2012 2/7/2012 Percussion No TB-2 1315.31 0.0 9.5 2/3/2012 2/4/2012 Auger No TB-3 1320.02 0.0 9.5 2/6/2012 2/6/2012 Auger No TB-4 1324.51 0.0 9.5 2/10/2012 2/10/2012 Auger No TB-5 1328.71 7.0 9.5 2/13/2012 2/13/2012 Auger No TB-6 1332.31 2.5 9.5 2/14/2012 2/14/2012 Auger No TB-7 1334.18 1.4 9.5 2/1/2012 2/1/2012 Auger Yes 4-5 & 8-9.5 TB-8 1337.11 2.2 5.0 2/2/2012 2/2/2012 Auger Yes 2.2-5 TB-9 1337.43 0.0 30.0 2/9/2012 2/14/2012 Percussion No
TB-10 1336.11 0.0 5.0 1/29/2012 1/29/2012 Auger No TB-11 1337.31 3.8 9.5 2/16/2012 2/16/2012 Auger Yes 5-9.5 TB-12 1337.43 0.0 30.0 1/31/2012 2/3/2012 Percussion No TB-13 1317.50 2.4 30.0 1/20/2012 1/23/2012 Percussion Yes 2.4-30 TB-14 1311.00 0.0 5.0 1/20/2012 1/20/2012 Auger No TB-15 1334.17 3.5 9.5 1/26/2012 1/27/2012 Auger Yes 7-9.5 TB-16 1334.45 2.0 30.0 1/24/2012 1/26/2012 Percussion Yes 14-30 TB-17 1337.25 0.0 9.5 1/25/2012 1/25/2012 Auger No TB-18 1307.21 0.0 9.5 1/21/2012 1/21/2012 Auger No TB-19 1297.50 2.3 9.5 1/19/2012 1/20/2012 Percussion Yes 2.3-4 & 5-9.5 TB-20 1300.21 4.1 12.0 1/19/2012 1/19/2012 Percussion Yes 4.1-12 TB-21 1318.32 0.0 30.0 1/26/2012 1/31/2012 Percussion No TB-22 1316.00 0.0 30.0 1/27/2012 1/30/2012 Percussion No TB-23 1333.43 0.0 9.5 1/28/2012 1/28/2012 Auger No TB-24 1327.50 0.0 5.0 1/18/2012 1/18/2012 Auger No TB-25 1336.12 0.0 9.5 1/31/2012 1/31/2012 Auger No TB-26 1336.00 0.0 9.5 1/18/2012 1/18/2012 Percussion No TB-27 1326.23 1.4 9.5 1/30/2012 1/30/2012 Auger Yes 1.4-9.5 TB-28 1326.50 0.0 5.0 1/27/2012 1/27/2012 Auger No TB-29 1323.11 5.8 9.5 2/12/2012 2/12/2012 Auger No TB-30 1308.10 0.0 9.5 1/24/2012 1/24/2012 Auger Yes 0-9.5 TB-31 1320.12 0.0 9.5 1/22/2012 1/22/2012 Auger No TB-32 1321.18 0.0 9.5 1/23/2012 1/23/2012 Auger No
BUILDING STRONG®
Geotechnical
Results – Depth
to Water Table
• Map below indicates
depth to water table
under airfield surface
Water
Table
Level
Terminal
BUILDING STRONG®
Geotechnical Results – Slope Stability
1. Static Case - Factor of Safety =
1.32 = Safe Slope
2. Dynamic/Seismic Case -
Factor of Safety = 0.57 =
Unsafe Slope
Arrows indicate where slope is located and potential direction of failure
Cargo
Warehouse
Road to
Cargo
Warehouse
BUILDING STRONG®
Geotechnical
Results –
Surface
Liquefaction
•This GIS map indicates
surface liquefaction potential
based off the borehole data
that was collected.
•The northern portion of the
runway, cargo warehouse,
CFR, domestic apron, and
Mid Air Base are most
susceptible.
BUILDING STRONG®
Geotechnical Results – Surface Liquefaction
TIA Master Plan 2010 - 2028
Future
International
Apron
Nepal Oil
Corporation
Future
Domestic
Hangars Remote
Domestic
Apron
Current
International
Terminal
Cargo
Warehouse
BUILDING STRONG®
Geotechnical Results – Liquefaction
Depths
Boreholes are extruded (10x) to showcase subsurface liquefaction potential
Terminal
BUILDING STRONG®
Point of Contact
Justin Pummell, GISP
Geographer
U.S. Army Corps of Engineers
+1 (808) 234-4633
