Embed Size (px)
Citation preview
Construction and testing of marine bridge foundation
By
Sing-lok CHIU, AECOM
Zheng-ru Fang, CHEC Construction (M) Sdn Bhd (CHEC)
Shi-jing, LIU, China Habour Engineering Company Ltd (CHEC)
Presented by Dr SL Chiu
AECOM, Hong Kong
29 November 2012 Page 1
Contents
29 November 2012
•Background of bored pile foundation
•Construction bored pile foundation
•Quality assurance testing of production piles
•Loading tests on the trial and production piles
•Test results
•Conclusion
Page 2
Background of Bored pile foundation
Main Bridge over navigation channel- supported on 4
piers- P24 to P27- by 66 bored piles , 2m in diameter,
socketted 2 to 6m in (Granite) bedrock
Approach bridge at eastern end- supported on 10
piers- P283 to P292- by 80 bored piles, 1.5m in
diameter, socketted 5 to 8m in (SHALE) bedrock
29 November 2012 Page 3
2nd Penang Bridge under construction
29 November 2012 Page 4
P24 TO P27
P283 TO P292
29 November 2012
Page 5
Main Span: Cable–stayed bridge
12-pile group 12-pile group 21-pile group 21-pile group
Pier P25 Pier P26
240 m
150m x 30m
117.5m 117.5m
Pier P27 Pier P24
29 November 2012
Page 6
Approach bridge
2x 4-pile group 2x 4-pile group 2x 4-pile group
55m
Geological conditions
29 November 2012 Page 7
Layout of bored piles
29 November 2012
Page 8
Main span piers (117.5 m + 240+117.5 m ) Approach bridge piers (55m apart)
7000 m
m
15, 240 mm
8 x ϕ1.5m bored piles 117,500 mm
12ϕ 2.0m
bored piles 21ϕ 2.0m
bored piles
Construction of bored piles
29 November 2012 Page 9
Main span piers Approach bridge piers
Grade III Granite
Grade III Shale
Protective casing in soft
marine mud 40 m 20 m 2.3 m
2.0 m 1.5 m
1.8 m
Slurry-supported bored hole
Toe-socketted in Grade
III or better bedrock 2 to 6 m 5 to 8 m
Engineering properties of slurry for the bore pile works
29 November 2012
Page 10
Slurry Density <1.25g/cm3
PH-Value 7 to 12
Viscosity in Marsh
Funnel seconds 32 to 60 s
Sand content
<4% (during drilling)
<2% (after drilling)
Reinforcement details
29 November 2012
Page 11
Pier numbers Main Bridge
Approach bridge
Steel Cage P24-P27 P283-P292
Top Section 36m (L)
44T32 (M)
T16x150 (B)
34m (L)
36T32 (M)
T12x 150(B)
Middle section 36m (L)
44T32 (M)
T16x150 (B)
24m (L)
18T32 (M)
T12x200 (B)
Bottom section Various (L)
22T32 (M)
T16x300 (B)
Various (L)
9T32 (M)
T12x 300 (B)
(L) Length, (M) Main reinforcements,
(B) Spiral binder
Concreting to marine bored piles
29 November 2012
Page 12
Concrete mixing plant on site and a temporary platform for piling works
Cement grout to cleanse
sediments at the pile base
prior to concreting
Concrete batching plants to
produce Grade 40/20 concrete
for bored piles
Quality assurance testing of bored piles
29 November 2012
•Interface coring
•Cross hole sonic logging
•Load testing
Maintained load test (MLT)
Statnamic test
Page 13
Interface coring
29 November 2012 Page 14
•To carry out on every production bored pile
• To verify the workmanship of piling work
•To take core sample through the pile base
•To inspect the concrete quality
•To measure the core length against the core run for
any missing material
Access tubes-
interface coring
sonic logging
29 November 2012 Page 15
250 m
m
200 m
m
Perforated section
4 x ϕ50mm
Access
tubes
2 x ϕ100mm
access
tubes
4 x ϕ50mm
Access tubes 2 x ϕ100mm access tubes
Interface coring (cont’d)
29 November 2012 Page 16
Typical core sample from interface
coring through a production pile
29 November 2012
Page 17
Interface coring (cont’d)
Minor imperfection at
the interface
Cross-hole Sonic logging (CSL)
29 November 2012 Page 18
The quality of the shaft concrete
of the bored pile was checked
using CSL to the ASTM D6760.
6 access tubes in total provided
to each of the production bored
piles, 4 of them 50 mm in
diameter and the other two 100
mm
Extracted from FHWA report
FHWA-CFL/TD-05-007 on Drilled shaft
foundation defects, October 2005 4 x ϕ50mm
Access tubes
2 x ϕ100mm
access tubes
29 November, 2012 Page 19
Cross-hole Sonic logging (CSL), cont’d
Cross Hole AnalyzerTM (CHA) system-
the equipment employed for CSL in
this project
Typical site set up for CSL
testing
Defects identification by CSL
Principle-
sound wave velocity and
energy may change as it
traverses through
material of different
densities
29 November, 2012 Page 20
Measurements-
First arrival time (FAT)
Energy reduction (ER)
Typical CSL results- Water fall diagram
Defects identification by CSL, cont’d
29 November, 2012
Page 21
29 November, 2012
Page 22
CSL field operation
- with CHA system
Transmission
probe
Receiver
probe
29 November, 2012 Page 23
Class Characteristics
1 Good Pile
First Arrival Time (FAT) and Energy Profiles are regular. Pile is good
2
Minor Anomaly
Some delay in FAT on the test profiles. Still within acceptable limits. Pile is
questionable
3
Major Anomaly
Two or more test profiles indicate major delay in FAT at similar depths.
Corresponding low energy curves observed. Pile is poor quality or flawed.
4
Defective Pile
Two or more test profiles having a total loss in FAT and corresponding
loss in energy curves. Pile is defective
The acceptance criteria for production bored piles subjected to CSL tests
CSL- Results interpretation, cont’d
Repair to defects in Class III and IV Two methods were proposed by contractor:
Method A- suitable for defected areas at shallow or
intermediate depths
involving use of reverse circulation drill to form access
hole to the defective area and hack off the defects in
concrete and re-cast the defected areas with sound
concrete.
Method B- suitable for defected areas at all depths
involving sinking of a series of drillholes to the defective
areas and cleansing of the defected areas by high
pressure water jet and filling out the affected areas with
high strength grout.
29 November, 2012
Page 24
Method A
29 November, 2012
Page 25
High pressure (40 MPa
max) water jet blasting to
hack off the defective
concrete
RCD to form access to
defected areas in pile
29 November, 2012
Page 26
Repair to defects in Class III and IV
RCD to form access to
defected areas in pile
High pressure water
jet blasting to hack off
the defective concrete
Fill out the
cleansed area
with sound
concrete
29 November, 2012 Page 27
Method B
125 mm @ 300 mm c/c-
spaced access holes are
sunk to defected areas
Concrete cutting nozzle to
deliver high pressure water jet to
hack off the defective concrete
CCTV to inspect the
cleansed area before
grouting
Loading Tests
29 November, 2012 Page 28
Pile- pier No L2-
P285
BHT 12-
P292
BHT9-
P25
Trial pile-
P25
diameter 1.5M 1.5m 2.0m 2.0m
Pile length (m) 106.4 89.5 125.1 115.07
Socket length (m) 6.3 m 2.06 m 8 m 4.32 m
Rock Type MD
SHALE HD SHALE
S to MD
GRANITE
S to MD
GRANITE
Type of load test ST MLT- top
loaded ST
MLT with O-cell in
socket
maximum test load 23MN 20MN 50 MN 38MN
29 November, 2012
1.88m
level of pile toe
lower plate of load cell
Upper plate of load cell
sea bed
pile head
Load cell
112.75m
115.07m
0.44m
2.3m
2.0m
-8.50m
-9.95m
-38.50m
-121.69m
-123.57m
Testing methods
Page 29
Maintained Load test
O-cell method
Trial pile at Pier 25
Pile dimensions:
Diameter: ϕ2.3m to ϕ 2.0m
Length: 115.07m
Socket: 4.32m in M to S DG
Loading method- embedded load cell
29 November, 2012
data
acquisition system
displacement transducers
hydraulic pump withpressure gauge
oil pipe
steel telltale rods
load cell
reference beam
shaft
side
shear
shaft end bearing
telltale casings
O-cell method
Page 30
29 November, 2012
Type
Outer
diameter
(mm)
Diameter of
Cylinder
(mm)
Upper plate
thickness
(mm)
Lower plate
thickness
(mm)
Height
(mm)
max. stroke
(mm)
YG565-
1002×5 1800 500 40 40 440 220
Instrumentation of the test bored pile
5 hydraulic jacks of
a maximum stroke
of 200mm
Access of tell-tale rods
to bottom plate
Page 31
29 November, 2012
Instrumentation of the test bored pile
TGCL-1
Vibrating wire type strain
gauge
Operational range: 2500 με
Resolution: 0.4 ~ 1 με
Waterproof – 150m under
water
Temperature: -20 to 80℃
WDL-50TZ
Linear Variable
Differential
Transformer (LVDT)
displacement
transducers
Page 32
19 20 21
P25 test pile
refrence beam
Reference pile 2
Unit：mm；
refrence pile 1
29 November, 2012
Layout of testing platform
Page 33
29 November, 2012
6 LVDT displacement transducers were installed,
namely
•2 for upward movements of the top plate of load cell
•2 for downward movements of the bottom plate of
load cell
•2 for upward movements of the pile head.
Instrumentation of the test bored pile
Page 34
29 November, 2012
Page 35
O-Cell
Vibrating wire type
strain gauges
Tell tale access
29 November, 2012
Test Results
Page 36
Test results (cont’d)
29 November 2012
Equivalent load settlement curve for the test pile
subjected to equivalent head down loading
Page 37
38101 kN
32.24 mm
Test results (cont’d)
29 November 2012
0
20
40
60
80
100
120
0 10000 20000 30000
Axial force（kN）de
pth（
m）
6689
8332
9974
11617
13260
14902
16545
18187
19830
-120
-100
-80
-60
-40
-20
0
0 50 100 150
Dep
th in
m
Max shaft resistance, fs in kPa
Shaft friction of P25
estimated
measured
Page 38
Maintained Load Test
-top-loaded method
29 November, 2012
Page 39
Test pile No. BHT12 @ Pier 292
Pile dimensions:
Diameter: ϕ1.8m to ϕ 1.5m
Length: 89.5m
Socket: 2.06m in HD SHALE
SPT-N Value
-88.8m
-22.4m
0.0m
Grade V Shale
Grade IV Shale
Marine Clay
Alluvial silty sand
ϕ1.8m
ϕ 1.5m
The test pile was equipped with strain
gauges and extensometers thus the
settlement of the pile base and
shortening the pile shaft as well as
the load transfer along the pile shaft
could be measured
29 November, 2012
Page 40
Maintained load test- set up
Top-loaded method
29 November, 2012
Page 41
Maintained load test-
set up
7 x 5000kN
hydraulic jacks
Pressure
synchroniser
29 November, 2012
Page 42
Test results of MLT on the Bored Pile BHT12 @ Pier 292
Pile top settlement vs Load Pile base settlement vs Load
29 November, 2012
Page 43
Cycle 1 Cycle 2 End of test
Test load, kN 16001 19943 0
S top (mm) 81.42 113.92 94.27
S base(mm) 59.78 86.89 84.65
Shaft
shortened, mm 21.64 27.03 9.62
Test results of MLT on the Bored Pile BHT12 @ Pier 292, cont’d
Load distribution along pile shaft
Statnamic load test
29 November, 2012
Page 44
Test pile No. L2 @ Pier 285
Pile dimensions:
Diameter: ϕ1.8m to ϕ 1.5m
Length: 106.4m
Socket: 6.3 m in MD SHALE
Test pile No. BHT9 @ Pier 25
Pile dimensions:
Diameter: ϕ2.3m to ϕ 2.0m
Length: 125.1m
Socket: 8.0 m in SD GRANITE
29 November, 2012
Page 45
Load cell and laser
sensor housing piston
Cylinder
silencer
Statnamic Test set-up
Gravel container
Reaction masses
Testing cylinder
Test pile
Piston mounting
frame
Extracted from the test report on pile L2-P285 by
Geonamic for CHEC on 29 July 2011 ( ref: DIR 11810)
29 November, 2012
Page 46
Statnamic Test set-up
Extracted from the test report on pile L2-P285 by Geonamic for CHEC on 29 July 2011 ( ref: DIR 11810)
29 November, 2012
Page 47
Statnamic load test
Extracted from the test report on pile L2-P285 by Geonamic for CHEC on 29 July 2011 (ref: DIR 11810)
29 November, 2012
Page 48
Typical output of test results of Statnamic load test
29 November, 2012
Page 49
Test results of Statnamic load test on the tested bored piles
29 November, 2012
Page 50
Test results of Statnamic load test on the tested bored Pples
Load vs Displacement (top)
Load vs Time (bottom) Load vs Time (top)
Load vs Displacement (bottom)
Force, displacement, velocity and
acceleration against time plots
Summary of test results
29 November, 2012
Page 51
Ratio of
fs/σv’
P292-
BHT12
MLT
P25-9
Statnamic
P25- Trial
O-cell
Clay 0.08 0.14 0.074
Medium
dense silty
Sand
0.09
0.145
0.04-0.05
Dense silty
Sand 0.11 0.03-0.05
CD Granite 0.04
CD Shale 0.12
Remarks Top-loaded tests- pile
head moving Downward
pile pushed up by
o-cell from below
P25-9
Statnamic
P25-Trial
O-cell
Maximum
mobilised
skin friction
in SDG
920 kPa 941 kPa
Concluding Remarks
29 November, 2012 Page 52
1. The works were fraught with difficulties and challenges given the
soft clay layer below seabed underlain by subsequent layers of
medium dense to dense silty sand above the rock head at a great
depth over 100 m.
2. The production piles were subjected to various types of quality
assurance checks:
a) Interface coring for existence of any imperfections at pile base
b) CSL for scanning the integrity of the shaft concrete
3. For those piles that were found containing imperfections, high
pressure water jet and subsequent backfilling of pressurised
cement grout were applied to rectify the defects and imperfections
in the piles
4. Different types of load tests were carried out on trial piles and
production piles for determination of design parameters and for
quality insurance check of the quality of the bridge foundation.
Thank You
29 November, 2012 Page 53
