Building Diaphragm Walls for Top-Down Construction & Bottom-Up Construction
                     Building Diaphragm Walls for Top-Down 
Construction & Bottom-Up Construction 
 
Top-down and bottom-up planning methods are two of the most popular approaches 
used in the construction industry. And building diaphragm walls is one of the most 
crucial stages of construction in building a deep basement structure using either top-
down or bottom-up method. 
Heritage Infraspace (India) Pvt Ltd (HIPL) is ranked as one of the best construction 
companies in India for its deep basement and underground construction services like 
diaphragm wall construction services in India for both top-down and bottom-up 
construction methods. Here, we brief you about how construction of the diaphragm 
wall in dams, metro stations, basement parking, etc. works, on both top-down and 
bottom-up construction. 
What is top down and bottom up construction? 
Tall buildings with deep basements and 
underground constructions like parking 
lots, underpasses, and subway stations 
are the two principal types of urban 
structures for which the top-down 
technique is applied. The technique has 
been applied to deep excavation projects 
where soil movements needed to be kept 
to a minimum but tieback or anchor 
installation was not an option. In this 
way, it is often possible to shorten the 
entire building period. 
Buildings with underground basements are typically created using the bottom-up 
approach, where substructure and superstructure floors are built one after the other, 
starting at the lowest level of the basement and working their way up. 
Although this traditional approach, often known as the bottom-up approach, is 
straightforward in both design and construction, it is not practical for large-scale 
projects with constrained construction time or site conditions. 
Diaphragm construction in both bottom up and top 
down construction 
Diaphragm walls help form the perimeter walls of the excavation site and push the 
surrounding soil back, preventing the excavation site from collapsing. A hydro fraise 
machine is typically used for diaphragm walls. A special blade attached to the boom 
arm of this machine allows a bentonite slurry to be pumped down to the cutters, 
preventing the excavated area for the wall from collapsing. 
The cutter descends to the desired level, and the slurry mixture aids in the preservation 
of the shaft. Rebar cages are then lowered into the shaft to provide reinforcement for the 
being built wall. 
While one wall is being finished by pouring concrete and pumping out the bentonite 
slurry, the process on the opposite side begins. Depending on the soil quality, it is 
sometimes possible to build diaphragm walls on both sides at the same time. HIPL 
has, in the past, achieved this feat, making it one of the trusted construction 
companies in India. Rebar is lowered into the completed shaft for wall reinforcement 
once more. Once all of the walls are completed, the excavation site will have a rigid 
vertical structure to keep the surrounding soil from moving and collapsing into the 
excavation area. 
When providing diaphragm wall 
construction services in India, once the 
excavation begins, posts or piles are driven 
into the ground to act as pillar supports for 
the earth retaining system. The struts are 
then installed as the next component of the 
earth retaining system. These are the 
horizontal braces that push the diaphragm 
walls apart and prevent them from inward 
movement. 
Struts are installed at regular intervals to keep the diaphragm walls apart as the 
excavation progresses downward. The base slab is cast once the desired level is reached. 
In top down construction, the roof slab is cast before excavation begins. Access shafts in 
the roof slab are constructed to allow for the delivery of machinery and materials below 
for further excavation of the lower floors. 
The intermediate level slabs are now cast, and struts removed as the structure takes 
shape. As the structure takes over the function of the struts in holding the walls apart, 
the struts can be removed as the structure rises. 
The slab casting continues upwards in the bottom up construction, as does the strut 
removal. Once the roof slab is cast, preparations for the construction of entry points 
begin with the removal of the final layer of struts. 
All struts are removed once the walls of the entry points are up and the roof slab is 
complete. Post this, the diaphragm wall construction gets completed and the next 
stage of construction of the basement continues. 
The points of distinction 
The top-down approach provides for minimum acquisition or demolition during 
development while allowing excavation to go on in heavily populated regions. Although 
switching back and forth between different procedures makes it slightly more difficult 
than the bottom-up approach, it enables the construction of stations in heavily 
populated locations. 
Working in such areas is difficult due to the slabs being cast as the excavation 
progresses downwards, especially for a diaphragm wall used in dams. The 
availability of fresh air, as well as adequate lighting, is critical for the continuation of 
work. Crane access is not restricted up and down the sides of the excavation during 
bottom-up construction. This method is faster than the top-down approach for sites 
large enough to have a perimeter area to accommodate construction equipment and 
when the excavation is not wide. 
But, a major point of advantage for top down construction is that it requires little or no 
temporary steel shoring, as a result producing good cost savings. Further, it requires no 
formwork for floors or roof too, which means significant savings in cost and time. 
HIPL has been providing crucial geotechnical solutions for large-scale residential and 
commercial construction, dam projects, metro and subway systems all over the country 
for over a decade now. To know more about our construction projects in India or to 
collaborate with us on your upcoming projects, get in touch with us today. Send us an 
email on [email protected] or call 079 26840355 
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