Stage 1.
1.
Before proceed with any works, survey and
setting out shall be conducted to
provide the guide on levels and alignment for
the construction of the Reinforce
concrete Retaining Walls.
2.
Survey and setting out shall be done in the
present of Resident Engineer or his
representative.
3.
Request for inspection shall be submitted prior
to start the works.
Stage 2.:
Earthworks (Excavation)
1.
Earthworks can only commence after the setting
out was done and accepted by
Resident Engineer.
2.
The sequence of the Earthworks is as the following
Diagram 1.
Diagram 1.
3. The
excavation at Sequence 1 will be done until it reaches the proposed platform
level
where it will provide wider temporary diversion during the construction
of the Retaining
wall structure.
4. The
excavation work at sequence 2 will only commence after the completion of
sequence 1.
5. The
sequence 2 will provide access for existing traffic during the excavation work
activities at sequence 1.
6. The
Layout after completion of earthworks activities for both sequences will be as
the
following Diagram 2.
Stage 3: Construction of RC Retaining Wall Structure.
Level 1: Piling Works
1. Piling
works will commence after the completion of first half of the sequence 2
earthworks.
2. The
sequence of the piling works will be done starting form the end Chainage
of the
Retaining wall progressing to the front Chainage.
3. The
excess of drive R.C pile will be cut as soon as the Piling works reaches
practical numbers of piling points to enable the pile cut off activities.
Level 2 : construction of the R.C Retaining wall Base.
1. The
construction of the base will commence as soon as after the preparation of the
pile head reaches the practical length of the standard steel bar supply length
or
available safe working area. (eg. Standard steel bar supply length / pcs =
12m )
2. All
of the installed reinforcement must be free from rust, properly tied and being
installed according to construction drawings and specifications.
Level 3: Concreting works.
1. Concreting
works will only commence after the installed reinforcement being
inspected and
accepted and approved for next sequence of works by Resident Engineer
or his or
her representative.
2. The
sequence of concreting activities will also start from the end chainage of the
R.C
Retaining Wall base.
3. Concreting
works will commence as soon as the installed reinforcement for the base
reaches
the possible delivery concrete volume to site per day and practical output of
the concreting works.
4. Prior
to concreting activities, all installed formworks for the base shall be
properly secure
to avoid formwork failure.
5. During
concreting activities, test cube and numbers of the cube to be prepared shall
be
as per directed by Resident engineer or his or her representative.
6. There
shall be no concreting activities during raining day.
7. The
flow of the installation of the reinforcements and concreting activities shall
be as
per diagram 3.
Diagram 3
Level 4: Construction
or R.C Wall.
1.
The construction of the R.C concrete wall shall
proceed as soon as the Concreted base
is ready to accept the next sequence of
the works.
2.
Construction of the wall shall start for both
side of the retaining wall concurrently.
However some section of the wall might
need to be left open to suite the site condition and
the movement of
machineries.
3.
R.C wall construction activities shall start
from end chainage of the retaining wall.
4.
The height of each wall that is ready for
concreting shall not exceed 2.4 meter high. This is
to avoid the formwork
failure.
5.
Prior to fully erect the formwork, wall
reinforcement must be inspecting by Resident engineer
or his representative for
acceptance and approval for next sequence of work.
6.
Prior to concreting activities formwork shall be
properly secured to avoid formwork failure
during concreting activities.
7. There shall be no
concreting activities conducted during raining day.
8.
Flow of the R.C
Wall Construction is as shown in the following Diagram 4.
Diagram 4
Stage 4:
Backfilling to completed Retaining Wall.
1.
Backfilling activities will commence as soon as
the fully completed section of the
retaining wall is ready to received backfill
material and also practically safe for the
other on-going construction
activities for remaining Retaining wall structure.
2.
Each layer of backfill shall be not more than
500mm thick and shall be properly
compacted before laying of subsequence layer
of backfill. This process is repeated
until the whole height of the retaining
wall if filled.
3.
Backfill activities will commence from the end
chainage of the retaining wall towards
the CH 6 + 200.
Stage 5:
Miscellaneous works.
1.
Miscellaneous works will commence upon
completion of the whole retaining wall
structure inclusive of backfilling
works.
2.
The miscellaneous works are the flexible
pavement, drains and road furniture.
Overall sequence of the stages:
Information is helpful. Suggest the particular problem situation is mentioned first; for example To avoid rocks falling from the hill side along road X leading to Town Y a RC concrete RW is suggested. The adjacent road is x m wide with dual lanes with shoulders on a flat land area on the opposite side of the hill. etc.
ReplyDeleteThe proposed RW is a cantilever RW with base 5m and depth 1.2m . Height 9.5m etc. etc. A method statement for the construction of the RC RW is to be written for the review of the Resident Engineer.