Resource Piling
Large Load Tests using a
Reaction System
RESOURCE PILINGS
BACKGROUND
Core businesses
Bored Piles
Reaction
System
Load Test
Secant
Piles
RESOURCE
PILING
Contiguous
Bored Pile
Wall
Kentledge
Load Test
Ancillary
Services
Achievements
Over 30 years of Piling (since 1981)
>489 piling projects completed
Grade L6 (unlimited piling contracts value)
Largest & deepest piles: 2.5m & 92m
Largest Kentledge in Singapore: 5,700 ton
Largest Reaction test in Singapore: 7,652 ton
Recent major projects: Sengkang Hospital, Marina Coastal Expressway,
Garden by the Bay, Marina Barrage, Singapore Deep Tunnel Sewerage
System, Business and Financial Centre, Tuas-A Power Station,
THE PROBLEM
Singapore is land scarce (~700 km2). However it has an ever growing population
(latest figures are above 5.3 million people). This dense population results in a
change in infrastructure design. Hence a need for taller buildings and
underground infrastructure.
Taller Buildings = Larger and deeper piles
BFC @ Marina South
The Sail @ Marina Bay
Deep Tunnel, soft soil = Larger & deeper piles
MCE C483 @ Marina Coastal Expressway
Therefore larger & taller load tests
These taller buildings and
deep underground
infrastructures (tunnels,
basements, etc.) require larger
and deeper piles. To ensure
that these piles have sufficient
capacity they are tested using
load tests.
A kentledge using concrete
blocks is one of the most
common method of doing a
load test in Singapore.
5700 ton Kentledge Test, Jun 10. Biggest in
Singapore
However... If not done properly
If it is not properly carried out, the outcome can be catastrophic. Such an
example is seen at the Gilstead road incident on 16 Jan 2011. A Kentledge
load test failed and blocks landed onto a public road causing:
Road closure & traffic congestion
Gas pipe disrupted / leakage
Church evacuated & Kindergarten temporary stop
Negative public perception
Deploy SCDF, SP Power Grid, Police, etc.
Reaction from authorities
WSH Councils alert
GEOSS committee
Guidelines on good
practices
Resource Piling (Mr. Foo
Hee Kang) invited
THE TEAM
The team
A team of management
staff, operational staff,
and safety personnel
was gathered to work on
a better solution to the
Kentledge using
concrete blocks for high
capacity load test.
Project Team
Name - Designation
Chairman
Foo Hee Kang MD
Technical
Advisor
Tan Hock Seng - GM
Leader
Benjamin Lee - PM
Facilitators
Calvin Ng
Coordinator
Mitram Gopal
HSE Executive (Keller)
Members
Donald Choo Plant Mngr
Kumaresan Site Mngr
Prabakar Site Engineer
SCHEDULE
Project planning
Team
formation
Root cause
analysis
Gilstead rd collapse
Design solution
Schedule of project
Schedule was
developed to plan and
monitor progress of the
progress
Corrective actions
were taken when
deadlines were not met
Overall progress was
in line with plan
Implementation
Oasis Hotel
Review
ROOT CAUSE ANALYSIS
Root cause analysis
The Ishikawa model along with the 5 Why model were
used to postulate the cause of the accident at Gilstead
road.
The main conclusions were:
Height of Kentledge leading to large toppling zone
Inadequacy of design
ALTERNATIVE SOLUTIONS
Alternative solutions
Description
Test time
Safety improvment
Statnamic
10 days
No dead weight but explosive
O-cell
8 days
Kentledge (steel plates)
35 days
Reaction system
15 days
All inside the pile. Good safety
improvement.
Reduced
1. height,
2. toppling zone
Reduced:
1. height,
2. lift,
3. Toppling zone,
4. Vehicular movement
4 alternative solutions to the Kentledge using concrete blocks were considered:
Statnamic test, O-cell, Kentledge using steel plates, and Reaction system (using
reaction from piles). The table above shows the test times and safety
imrovements. Further analysis of the solutions are on next slide.
Alternative solutions
Statnamic
O-cell
Steel plates
Reaction
system
$7.8 million
$0.78 million
Estimated cost of steel
plates for a 7,068 ton
Kentledge test is S$7.8
million. This is a huge
investment.
Estimated cost for a
7,068 ton Reaction
load test is S$0.78.
Explosive
Statnamic is an
explosive test. There
are inherent risks
with the handling
explosive material
especially with
increase of test
loads.
2 main difficulties with Ocells are in terms of the
design (accurate
placement of the O-cell in
the pile) and quality of
construction (especially
with the concrete just
below the O-cell).
Hence this is the
preferred option
Current Capacity Limitations
However, reactions systems capacities have so far been in the range of 1,500
tons to 2,000 tons. Hence the Reaction System load test would need to be redesigned to allow test of more than 4,000 tons.
Addition factors considered during the re-designing process were
- Ease of transport,
- Assembly technique,
- New safety risks (if any),
- Time of fabrication,
- Detailed cost calculations
- etc.
SELECTED SOLUTION
Reaction system
Test Pile
Reaction
Piles
BENEFITS
Height reduction
15000
3750
21,145mm
16,500
5250
A 7,068 ton Kentledge using
concrete blocks (left) would
require employees to work at a
maximum height of 21.2 m
whereas a Reaction load test of
the same capacity would
require employees to work at a
much reduced 6.4 m.
21.2m
7500
838
912
1400
6.4m
1300
2176
835
760
338
381
2000 Pile
Head
5400
3350
3350
5400
Toppling zone
15000
3750
Height:
21.2m
21,145mm
16,500
5250
Height:
6.4m
7500
838
912
1400
1300
2176
835
760
338
381
2000 Pile
Head
3350
3350
5400
78.6m
5400
Area = 5,300 m
78.6m
Area = 900m
A 7,068 ton Kentledge using concrete
blocks (left) has a toppling area of
5,300 m2 whereas a Reaction load test
of the same capacity has a toppling
area of 900 m2
Benefits at a glance
Reaction
System
Height
Toppling
Zone
Lifts
Traffic
Cost
15 m
4,400 m2
3,900
425
S$ 182,000
(70%)
(83%)
(97%)
(94%)
(15%)
Reduced
Reduced
Reduced
Reduced
annual
savings
Figures are based on 7,068 ton tests
Figures compares a Reaction System load test to a Kentledge load test using concrete blocks
Savings calculations are based on annualized costs and includes estimates of life cycles of materials such
as concrete, steel, jacks, etc.
DESIGN & STANDARDIZATION
Design & Standardization
The solution is standardized through the
following methods:
Engineering design
Method Statement
Risk Assessments
Safe Work Procedures
IMPLEMENTATION
Communication
To ensure successful implementation of the solution, the work procedures, risks and
hazards need to be communicated to the supervisors, and workers. The following are
the main methods used to communicate the solution:
Discuss with execution team
Brief RA & SWP
Brief lifting plan
Pre-start talks
Execution
Having communicated the solution, the work is executed on site. Execution is monitored
at several points to ensure that work being carried out complies to safe work
procedures, risk assessments, permit-to-work (PTW), etc.
Execution
An example of the completed setup (a 7,652 ton) load test using the Reaction System at
Ophir road, Singapore.
EXPANDABILITY
Projects completed
Project
Test Load
Done on
Oasis Hotel @ Peck
Seah St.
5380t
2012 Aug.
M+S Project @ Ophir
Road
7652t
2012 Nov.
7652t
2012 Nov.
6240t
2013 Feb.
5046t
2013 Apr.
6240t
2013 Mar.
7532t
2013 May
TRX(Tun Razak
Exchange @
Malaysia)
7500t
2013 Oct
7500t
2013 Oct
Tampines Town Hub
@ Tampines Ave.4
7068t
2013 Nov
RESULTS
Results
Tangible results
o
o
o
o
o
o
Height of load test
Work-at-Height exposure height & hours
Number of lifts using cranes
Toppling zone
Vehicular movement on the road
Productivity
Intangible results
o Workers morale
o Safety awareness
o Public perception
= Reduced
= Reduced
= Reduced
= Reduced
= Reduced
= Increased
= Improved
= Improved
= Improved
