BOX PUSHING IN ADVERSE CONDITION
PREPARED & PRESENT
BY
DINESH CHAND , SRDEN/HQ RAJKOT WR
DURING
ADVANCE BRIDGE & GENERAL COURSE
COURSE NO.822 FROM 21.4.08 TO 16.5.08
AT
IRIC EN PUNE
Description of work
Proposed Laying of Various Dia. of Petroleum Product
M.S. Carrier Pipes through 3 X 2 X 7.50 X 2.20 R.C.C. Box under the Track at Km.
857/9-11 between Kanalus and Motikhavdi Stations for Reliance Petroleum Ltd.
Jamnagar. In this work three segments of twin boxes having size 7.5m x2.35 m (internal
dimension) were to be cast outside and then they are to be pushed under the track by
applying horizontal force after digging ins ide the box. Rest of the work in Railway
premises to be done as a cast in situ box. The above work is to be done for M/S
Reliance for transporting petroleum products required for new export refinery which is
being developed at a rapid pace.
Location of line
The propped work falls on a goods line between Kanalus and Sikka
of Ahamedabad Okha BG single line of Rajkot division of western Railway.
OKHA
SIKKA
SITE
RJT
KNL
S
VG
ADI
Salient features of Box
Box S ize
: 3 segments of 2 X 7.50 X 2.20 m (Clear)
Pushing Length
: 22.50 met
Cast in Situ Box Length
: 40.00 met
Total Length
: 62.50 met
Project Cost
: 290.55 Lacks (in railway portion only)
Grade of concrete
: M35
concrete per RM
: 28.275 Cum
Dead weight of twin box
: 1600 Mt.capacity
Thickness of top and bottom slab of box : 750mm
Thickness of wall was
: 500 mm
Cushion
: 2m
Bank height at Box location
: 2.7 meter.
Work was supervised by M/s Rites
Box Dimensions:
Rai lway Track
Embankmen t
7.50m
2m
2.35m
R.C.C Box Segment-I
R.C.C Box Segment-II
R.C.C Box Segment-III
How site condition deteriorated
On 1st July 2007 heavy rain took place from
Rajkot to khambhaha in a stretch of 150 km. Major breaches took place at 04
(four) locations between Rajkot and Kanalus station of Rajkot division. The
goods line from Kanalus to Sikka on which proposed work falls was isolated and
goods loading/unloading was completely stopped. Advantage was taken to push
all three box segments by cutting embalmment as it was expected that traffic will
not be restored at least in next 7 days. So work was taken on a mass scale by M/s
Reliance. Two segments of twin boxes i.e. 2 * 7.5 m*2.2 m has been successfully
pushed through. Third segment was pushed through unto first edge of
embankment. At this stage due to further heavy rainfall and failure of most of
pushing jacks, work was to terminate at this stage. The earth in the form of
crushed stone was filled and track was relayed. Mean time breaches at all four
sites were attended and traffic restored to normal.
rd
Due to loose soil at the location of 3 segment; it was not possible to push box in
normal way as there were 100% chances of falling loose soil during pushing.
Efforts done to overcome problem
Followings methods were tried to overcome difficulty of falling of overlaid loose
soil
• Stabilization of soil by Bentonite
It was thought to use Bentonite to
strengthen loose soil. The Bentonite was injected at closure spacing from top of
embankments.By use of Bentonite, soil gets compressed and stabilized. M.S.
plate in horizontal direction at centre of Front shield was provided to stop sliding
of soil. Now digging started but unfortunately slope inside box started collapsing.
Work was stopped again. The scheme was not successful due to presence of
crushed stones in large proportion.
M.S. Plate in Horizontal direction at centre of
Front sheild to stop sliding of soil.
Extra M.S. Plate
R.C.C B ox
• Complete block ing of line
It was thought to block the line completely for 3
days being a goods line. But due to continuous loading and unloading of rakes, it
was not economical as work was not so much urgent. However, there were spells
of 3 to 4 days available but these spells could not be predicted. Agency desired
for confirmation of block at least 7 days before start of block. Due to no
confirmation given by Railway and also keeping in mind no urgency of work,
this scheme was dropped.
• Use of relieving girder
The work could be done by use of relieving girder of 30m
or more .As location falls in a rising gradient, a minimum 30 kmph speed was
must for single loco. Speed lim it at relieving girder site was 10 kmph. Double
loco system was not introduced due to scarcity of diesel locos. Due to these facts
use of relieving girder was not suggested.
• Supporting track transversely on two end beams
A meeting was done with M/s
Reliance and their contractor for finding out scheme. During meeting a scheme to
support track transversely on two beams were discussed. A tentative scheme with
design calculation submitted by agency which was cheched,modified and
approved by CBE. The detail scheme was as under.
10m long ISMB 450*300 were to be inserted between sleepers. One end of this
ISMB was to be supported on longitudinal RCC beam cast parallel to track at a
distance of 6 m from centre line of track while other end was to be supported on
top of vertical column made of CC crib on top slab of RCC box. A steel plate of
10 mm thick was to be placed on top of box and also below bottom of CC
column. A lubricant was to be fed between these two plates so that a relative
movement takes place between bottom plate fixed to RCC box and bottom plate
fixed below CC cribs. Due to relative movements, crib to be remains at fixed
location while box to be move ahead on jacking. Beside this, bottom plate under
CC crib was also to be kept tight by rope and Pulley. The transverse beams were
to be tied to each others by channel parallel to track at both side of track.
Sketch of Supporting System:
R.C.C Beam Casting:
Execution methodology
•
•
•
•
•
•
•
Erect CC crib staging over the existing Pre cast Box to be pushed with
10mm M.S. plate on top of box & bottom of CC crib with lubrication in
between.
Cast 450 X 600 mm RCC beam on the other side of the track.
Push ISMB 450 girder one by one in between the sleepers by removing
ballast & excavation if required and fill the gap between sleepers with
ballast.
After completing the above supporting arrangements of track pushing of
box will be done slowly at the rate of 250 mm at one stroke excavating
max 300 mm earth from inside of box in one time. Filling of earth above
box shall be done simultaneous ly.
Pushing will be completed by repeating the above.
The supporting arrangements of track are in addition to the normal safety
arrangements for box pushing works.
After box pushing the rail traffic will to be opened only after filling the
earth back upto track & erecting the track fit for movement by Railway
Engineer Incharge
Execution
Earthwork on opposite side of the box was done, rammed and rolled to the
desired MDD and OMC for the purpose of resting CC beam. As per drawing CC
beam of size 450 X 600 mm was cast on rolled earth at a distance of 6m from
centre line of track having length 2 meter more than width of box. A plate 12 mm
was fixed on top of slab. Lubricant was placed on this plate.
On this plate, a CC cribs having
bottom plate was fixed .The CC
cribs were braced to each other
.Top of CC crib and CC beam
was kept 450mm below bottom
of rail to facilitates insertion of
ISMB.
SR 30KMP H was introduced
and one lookout man deputed
on the track to ensure safety of
track.
ISMB 450 X 300 mm were
inserted into the sleeper spacing
one by one in all the spans in
entire width of the box. One
ends supported on CC
cribs and another end supported
on precast CC beam. Full
packing of sleeper and ISMB
ensured after insertion of
ISMB. All ISMB braced with
each other. Now we are in a position to take the complete load of the train on CC
cribs rested on precast box on one side and on precast CC beam on other side
through ISMB 450mm
Approx 1000 of filled sand bags were kept ready to meet any unforeseen
problems on work site.
MS plates placed on box tightened with horizontal chain pulley to pull the plate
simultaneously when box pushing started.
Box was pushed up to 4 m distance from centre line of track before supporting
arrangements prepared.
A team of 20 labor of contractor kept ready to meet all the problems with the
track and for packing and aligning the track and to meet with other problems.
The total weight of twin box was 1600 MT so 12 number of jacks having
capacity 150 Mt each were utilized for pushing the box i. e. 6 jacks on each box.
Two numbers of bobcats were utilized to remove the earth from box and manual
labors utilized to remove the earth in fronts of cutting edge. One crane was kept
ready to meet any emergency.
Box pushing started and simultaneously it was ensured that plates were tightened
with the wire ropes and horizontal pulleys. Main purpose of this was to get
relative movements between box and MS plates placed on it.
Problem came during pushing work when formation of earth started to fall
beyond last ISMB i.e. to near to edge of the box. Work was required to stop for
sometime and two extra ISMB each end inserted into the spacing beyond the
width of the box and collapsed earth was supported by placing filled sand bags.
Pushing work was started slowly by removing earth from inside of box and then
jacking. The pushing beyond other edge of sleeper could not be done due to
falling of earth toward CC beam as distance of beam from edge of collapsed earth
remains 02 m. Now it was decided to
construct a CC wall on the edge of the box,
approximate 0.5m width and up to the
bottom of the rail. After construction of
CC wall earth was filled between this CC
wall and CC cribs on the box and slowly
loads of the track transferred on newly
filled formation earth retained by CC wall.
After doing above work approximately 30
cm pushing done again and work of
pushing was then stopped .Now precast cc beam was dummy and was require to
remove as box was require to cast at that location cast in situ. ISMB inserted in
the sleeper spacing removed one by one. Ballast putting and packing work done
simultaneously.
Further improve ments to scheme
The ISMBs were laid in a width of
box plus 2m only. When excavation
was started collaps ing of earth from
side of box also started along with
collaps ing earth ahead of the box
which was not thought
off.However,the collapse was
prevented by providing sand bags as
well of CC cribs along sides of box .Also additional ISMBs were provided on
both sides of box.So,additional requirements of ISMBs should be provided to
cater side collapsing of earth.
What was lubricant
Availabilty of relieving girder
Nos of rakes per day
Material transported
Inches of rainfall
Role of lime grouting
Bentonite from top or elsewhere