VietNamNet Bridge – A sinkhole suddenly appeared on Hanoi’s Le
Van Luong Road after a tropical typhoon, the Song Tranh hydro-power dam was
cracked after earthquakes…
People question if these works
were damaged by natural calamities or if natural calamities unmasked the poor
quality of these works?
At around 7.30pm, August 19, a
big hole appeared on the expanded Le Van Luong Road, a project to welcome
Hanoi’s 1000th anniversary.
On August 20, the hole kept
spreading to more than 20m wide, 30m long and 7m deep, causing serious traffic
jams on Hanoi’s key role. The hole is very close to the USilk City apartment
building, invested by the Song Da Thang Long JS Company.
Nam Cuong Group, the investor of
expanded Le Van Luong Road, claimed the construction of USilk City apartment
buildings as the reason causing the sinkhole on the road. Meanwhile, the
investor of USilk City laid the blame on downpours.
An official from the Hanoi
Traffic Inspection Agency said the under-construction project might have weakened
the supporting material of the soil and broke the underground water drainage
system, causing the sinkhole.
On August 21, the Hanoi
Department of Transport and related agencies unexpectedly concluded that the
hole was caused by downpours, resulted in depression. The conclusion was a big
surprise because the department set up a working group to find out why the
sinkhole appeared. Meanwhile, the independent inspection team did not confirm
the reason yet.
The expanded Le Van Luong Road is
2.7km long, linking Hanoi downtown to Ha Dong district. The construction was
kicked off in April 2009, with total investment of VND676 billion (around $340
million).
According to the Vietnam News
Agency, this project is still under the warranty period. This incident has
stirred up the public’s concern over the quality of this work.
Earlier, Hanoi people were
worried about big cracks on the Thang Long Bridge, which still appeared after
several times of mending. The cracks are said to cause many accidents,
especially at night.
Vietnam News reported that nearly
40 serious accidents, with 12 fatalities and many others injured have occurred
since January 2010, when the bridge cracks began appearing. Many cars and
motorbikes have damaged their tires and wheels while travelling along the
bridge.
The Vietnam Road Administration,
as the builder of the bridge, was looking for partners to help develop a
comprehensive project to repair the bridge and resolve any ongoing problems.
The administration has also asked the Department of Road Management and
Construction to supervise the repair work carried out by Bao Quan Investment
and Construction Joint Stock Co, the project contractor, and hasten legal
procedures to hand over operation of the bridge to the city.
Thang Long Bridge was built with
Russian assistance in 1985, crossing the Red River to connect Noi Bai Airport
with downtown Hanoi. Authorities spent roughly VND100 billion ($4.8 million) on
resurfacing the bridge in 2009, but severe cracks have since appeared.
According to experts, one of the
reasons for the poor quality of the road surface is that the rolling and
pressing process of the stone mastic asphalt was below 120 degrees Celsius,
negatively affecting the quality of surface. Rainwater draining systems also
have not worked properly, also leading to stagnant water standing on and
damaging the bridge's surface.
Another work that was also
damaged in downpours is the major dam in Cua Dai, in the central province of
Thanh Hoa. On October 5, 2007, because of downpours in the upstream region, a
large volume of water flew to Cua Dai reservoir.
Under water pressure, around 100m
of Cua Dai dam was broken. Flood swept away around 600,000cu.m of soil, causing
losses of nearly VND200 billion (around $13 million). Thousand houses in Tho
Xuan district were submerged.
Experts said that the incident
originated from mistakes of the dam constructor.
The Cua Dat water reservoir is
the largest national irrigation work and hydro electric-power plant on the Chu
River, 17km from the Bai Thuong dam.
The Ministry of Agriculture and
Rural Development is the main investor of the project along with contractors
including the Vietnam Construction and Import-Export Joint Stock Cooperation
(Vinaconex).
The VND7 trillion (around $470
million) project consists of two components. The Cua Dat reservoir--with a full
capacity of 1.5 billion cubic meters, and Cua Dat hydro power plant. The
project was kicked of in 2004.
The Song Tranh 2 hydro-power dam
in the central province of Quang Nam was cracked and leaked in March 2012 after
earthquakes.
Experts from the Ministry of
Construction confirmed that water leakage at the dam was caused by errors in
design.
Dr. Bui Trung Dung, deputy
director of the State Agency for Assessing Quality of Construction Works and
the leader of the Ministry of Construction’s inspection team at Song Tranh 2,
said on March 21, that the dam does not have a water pipe connecting the left
basement to the right basement to the downstream. Consequently, stagnant water
easily runs through elastic slits and absorbs through the dam.
Mr. Dung also said that there
were errors in design inspection and consulting-supervision. Moreover, the work
is during the two-year period of warranty but the contractor did not work
closely with the investor to fix errors.
The total investment capital in
this project is VND5.194 trillion (around $350 million). The construction
started in March 2006. The Song Tranh 2 reservoir is over 730 million cubic
meters in capacity.
In HCM City, the South East
Asia's largest underwater tunnel, Thu Thiem, was in early August reported to be
plagued by cracks after just nine months of operations.
Thu Thiem tunnel is the first of
its kind in Vietnam, consisting of four 1.5km long sections with a six-lane
road.
In 2008, the four pre-built
sections of the tunnel developed a series of 2-3 meters long cracks on the
ceiling and walls. But these were fixed and passed inspection prior to the next
stage in 2009.
When the tunnel was first put
under water in 2010, the cracks appeared again at over 109 locations. The
independent consultant, Oriental Consultants Company, said it was still within
acceptable tolerance levels.
Thu Thiem Tunnel was approved for
operation in November 2011. However just after nine months of operation, cracks
were detected during routine maintenance by the HCM City Department of
Transport.
Experts said that the tunnel was
not cast properly or the tunnel casting technology is inappropriate to
Vietnam’s condition.
Despite being in operation for
only 2-3 years, many bridges in HCM City which cost hundred million USD have
fallen into a state of disrepair, with cracks and erosion, according to Dan
Tri.
Construction on the Thu Thiem
Bridge, across Saigon River linking District 2 and Binh Thanh District, started
in August 2005, and cost nearly VND1.5 trillion (US$71.4 million). The main
part of the bridge was put into use since 2008 and the other parts were
completed in late 2010.
However, since 2010, the bridge
section in District 2 has showed serious signs of erosion. The contractors have
been struggling to deal with the problem.
In September 2011, erosion spread
and the bridge started showing cracks in a number of sections. Despite numerous
repairs the deterioration has continued, with erosion reaching 10 meters at
some points and concrete bars showing additional cracks.
On June 28, 2012, contractors
made another attempt to fix the erosion problem but the cracks on the concrete
bars have not yet been dealt with.
Phu My Bridge is in a similar
state. Open to traffic since September 2009, and costing VND1.8 trillion
(US$85.7 million), it is considered a symbol of HCM City. Nevertheless, just a
short time after becoming operational the bridge had potholes in the section
running through District 2.
Other problems have also been
found at many overpasses along Vo Van Kiet Highway, which has only been open
for one year.
Experts said that the areas where
bridges are located have weak foundations. Lax geological surveying has led to
the use of improper foundation consolidation techniques, which can be blamed
for the cracks and subsidence. Such problems should be taken into account early
in the design process.
Compiled by P. Lan
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