Tải bản đầy đủ - 0trang
Structrural steel is from Vietnam, JIS G316, SM 41, SM 50, SM 50Y, SM 53. Standard.
Additional, Contractor carry out investigate electric, water,
telecommunication cable underground and traffic road,
house…on the plan to make a method to remove,
dismantle or select a suitable execution method, ensure to
the most economize. and cooperate closely with supervise
consultant or sign a contact with water supply, electric
underground cable system, telecommunication company
to be early determine underground systems in site zone,
then giving a method to solve on time.
2. Treat to irresistible situation
In during excavation and execution process, although
investigate carefully but it will be happened some
irresistible situation as follow:
a. Natural disastrous ( rain, storm, flood, fire...)
Rainstorm, flood: Contractor make a plan to establish a
board specialize to prevent storm and flood with functions
are always observe weather and pre-training situations
which are able to occur. If raining heavy all works at site
will be stopped and finding urgent and on time method
treatments. All execution equipment must move to safety
place. Structures that are half-done has to braced,
covered to ensure safety.
Contractor also contact closely with Local storm-flood
preventing board to cooperate in actions as well as obey all
requirements of board in other level of flood and storm.
b. Bomb & mine
Checking bomb and mine is not in scope of work of C3, but if
in during construction process found out bomb or mine..., we
will inform to Owner, Main-Contractor and other functional
organization at one, to evacuate every people, equipment
away quickly, avoiding far from dangerous place. using hard
fence to close that place and marking by flag, warning
board, appoint people guarding 24/24h until hand over to
Only carry out execution when mine or bomb have been
treated absolutely safety.
c/ Sand in mud status:
When executing if occur mud-sand phenomenon,
Contractor will halt execution at one, and applying
emergency methods to limit of bad result, then inform
Owner, Main-Contractor, and Contractor put forward solution
method as follow:
- Stop excavation, fill back to limit damages
- Inform to Owner and Main-contractor.
- Considering and prevent or change stream flow
- Using bamboo pile (steel pile) to separate the mudsand zone with other else.
- Continuous excavating foundation (more deeply than
designing are about 300-500mm), using Geotextile to
spread over then fill on by stones, gravel for fixing,
beside that has to use a pump with high capacity to
pump water out of foundation pit. Mobilize
manpower, equipment, materials to execute quickly
and finish step by step.
- Needle-filter-well method can also be used to prevent
from sand silting phenomenon, this method is very
effective, however, it's high price so depending on
case, conditions that applying to be reasonable
d. Antiques and relics of history
During construction process, if appearing antiques or
historical relics, Contractor halt execution at once, inform to
Owner, Main-Contractor and other functional organization.
using hard fence to close that place and marking by flag,
warning board, appoint people guarding 24/24h until hand
over to functional organization.
e. Electric, telecommunication, water supply system…
During construction process, if appearing Electric,
telecommunication, water supply system, Contractor halt
execution at once, inform to Owner, Main-Contractor and
other functional organization. using hard fence to close that
place and marking by flag, warning board, appoint people
guarding 24/24h until hand over to functional organization.
3. Locating canal line
Base on documents of Main-Contractor, border-line of Owner
which has been handed over, Contractor will carry out
survey, locate and show the line of canal. Maintain landmark
by placing concrete outside scope of building (Note that, the
place of putting landmark must be few means moving on
with intending to prevent from hitting of means coming and
going there). The centers of landmark will be determine
correctly by Theodolite and it must be intersecting points of
center lines. then this central point will be expanded to more
4 points which have 2m distance far from central points with
4 directions. This 4 points will be used for testing and
checking in whole time of construction process.
3. Inspection and as-built drawings.
B- execution statement
Cause of almost of works will be executed in/on water so
depending much on weather, underground water level of
specified points, zone.
In VietNam the rainy season is from June to August (mainly
on July). and other left is dry season, this season is quite
good conditions for execution
II. Execution statement of C3 package
According to Contractor' points of view, C3 package is
divided into 3 independent line (section) and 2 works as
- Line 1: This section is reinforced by stone masonry
on slope, it is lied between pump station and Uong
bi bridge No2.
- Line 2: This section is not reinforced slope but there
are 2 coffer dams run along side, It's lied between
Uong bi bridge No2 and Uong bi bridge No1.
- Line 3 : This section is not reinforced or banking
cofferdam. It's lied between Uong bi bridge No1 and
- Work 1: Intake bay and trash & log boom, revetment
- Work 2: Swing wall of pump station.
With above zone definitions depend on characteristic of
engineering requirement, as well as method statement.
Contractor will carry out work as follow steps:
II.1.1. Line 1: execution statement
will have a independent team take responsibility of execution
this section. All execution equipment and material will be
mobilized to Uong bi bridge No3 by existing road, then
carrying out execute expanding follow two directions. Step of
execution will be followed:
a. Step of excavation and banking cofferdam :
- Water in this zone will be discharged through a culvert to
Uong bi river
- Then using excavator, Crawler tire run along line to
excavate all mud layer and organic layer on the topsoil,
one part of excavated soil will be used to bank a small
temporary dyke for execution and other left will be
transported to outside by special truck. However, to have
starting point for Excavator and truck operate, need to
make wooden raft and temporary road for them standing
- After mud layer excavated and removed, under layer is
2b, with purpose reuse this layer. We will continuos use
excavator and truck to exploit all 2b layer then gathering
to a specified ground for drying up, this quantity will be
use to bank cofferdam of another place, this layer can be
exploit from 6-6 section to 11-11 section with quantity is
about 135 350 m3. to keep drying for excavating need a
high power pump to prevent water coming.
- Layer next is 2d (sand), with this layer is also for used
later so when exploit 2b layer finish, we shall pump water
in canal line then using a dredger to suck sand from 2d
down to bottom of canal that sand will be gather to a
ground for reuse late
The section of canal after executed by Dreger is not
correctly as design so it must use a excavator on a barge
for repairing slope in accordance with design.
b. Structures and execution
statement of canal
The standard for selecting canal section in this line is trying
reuse excavated soil, however, it must has structural
solution to ensure the dam stable and economize.
Structural solution and execution method for banks &
cofferdam as follow:
Excavate all weathered layer (mainly is 2a layer), this one
will be move to beside cofferdam,
Core of cofferdam will be filled by sand(2d), right and left
slope filled by clay (2b) to bar absorbent water with slope
factor is 3
We have calculated for absorb stably and slip stably for dyke
section by Geo-slope (Seep/w vµ Slope/w) program giving
absorbent gradient of lower section is 0.3, slip factor
calculated by Bishop, Kminmin=1.924.
The inner slope will be protected by PDTAC-M(Precastconcrete slope), outside slope will be seeded.
c. Step of slope reinforcement.
Line 1 is located in Uong bi town, so this part will be
reinforced by precast-concrete to make landscaping more
beautiful and cleaning, and prevent absorbent flow will not
roll sand with to lead blow off canal dyke, hereafter we will
show some reinforcement method of canal dyke.
* Stone masonry
This method in "request for quotation" documents in
previous period has been studied. From 9-9 to 11-11 section,
slope and canal bottom go through clay layer 2b so pumping
dry foundation pit to mason tone for protecting slope, but
from 1-1 to 9-9 section, slope and canal bottom go through
sand layer 2d and 2c so making foundation pit dry for stone
masonry is not easy work. So to execute this part need use
underground water level under bottom of canal, in the same
time must decrease absorbent water output, thus around pit
have to use steel pile to close this zone. Moreover the water
speed in canal is very low and go through weak soil, the
consolidation of canal during operating. At that time need to
dredge canal bottom, this work only can carry out by
machine in about 20m central line of canal to avoid untablize
stone masonry at foot of slope .
* Precast-concrete carpet PDTac-M solution
- PDTAC-M carpet is a kind concrete carpet that automatic
chocking with using a steel net, this one used to protect
for building with flooded bank, they are precast
reinforcement concrete, front surface is hexagonal in
shape, behind surface there are 3 automatic chocking
foots which is hooked, fixed on available steel net. Carpet
pices joined nearly with automatic link in 3 directions and
defending voids to prevent absorbent water flow in bank
running out that damage to stability of slope.
- With this structure, steel net act as buffer float to against
settlement, distribute load regularly of carpet on weak
soil, limit settlement phenomenon on some points of
concrete carpet and 4 edges of one mesh set up a border
to restrain the contact among carpet tiles, the void among
carpet tiles is small, regular enough to form joints which
restrain minimize the bending force on carpet tile, and
stretch force in steel net.
- P§TAC- M precast concrete carpet there are 2 parts: Carpet
net is knitted by steel d6-d8mm to make Sin in shape,
with length from 10-80m, 2.6-3.2m width, around by
border and inner is divided by steel d12-d16mm, then
putting carpet tiles on to make a continuos carpet.
- Concrete carpet is able to up 10-80m length or longer, at
present it is able to cover all slope. the area of carpet can
be changed depending on design, and able to execute 4
carpets about 800m2 per day.
- with flat surface will be easy for running water, make
more beautiful landscaping, environment, Behind surface
is a foot system which is fixed in slope foundation that will
make strong ability in nonslip of carpet tile.
- Carpet is constructed with steel float to against settlement
and could execute in water easy by crane on float, this
automatic-concrete carpet enough stability in long term