Building foundations of tomorrow
Diaphragm wall construction in India is the building of reinforced concrete walls that are constructed in the ground using an under-slurry technique. This basement diaphragm wall technique involves excavating a narrow trench that is kept full with an engineered fluid or slurry. This slurry helps to prevent the sides of the trench from collapsing and it also provides a barrier against groundwater. Once the trench is excavated, the concrete is pumped in and allowed to harden.
Also known as D-walls, they are commonly used in the construction of deep basement diaphragm wall construction in India and other structures that require a strong and stable foundation. They are also used to prevent soil erosion and to control groundwater levels. Heritage Infraspace, as an Ahmedabad-based diaphragm wall construction company in India, offers a wide range of basement construction services helping clients design, engineer and construct a diaphragm wall that meets the specific needs of the structure.
Diaphragm wall construction is a fairly new methodology of basement diaphragm wall construction and can be used in a variety of soil conditions. They are very strong and durable and can be installed close to existing structures.
What is a diaphragm wall made of?
A diaphragm wall is a type of reinforced concrete wall that is constructed in the ground using an under-slurry technique. This technique involves excavating a narrow trench that is filled with an engineered fluid or slurry. The slurry prevents the trench from collapsing and blocks groundwater. The concrete is then pumped into the trench and allowed to harden.
The process of diaphragm wall construction
Diaphragm wall construction projects are very meticulous. Here’s an overview:
Fixing of Alignment
Establishing the correct position and alignment of the diaphragm wall using surveying techniques and marking it on the ground with stakes or spray paint.
Guide Wall Construction
Building temporary guide walls on both sides of the planned excavation area and ensuring accurate trenching and support during diaphragm wall construction.
Trenching
Excavating the trench along the marked alignment to the desired depth and width for the diaphragm wall using a special machine called a hydraulic grab or cutter to dig through hard soil or rock layers.
Trench Cleaning
Removing loose soil and debris from the trench to create a clean surface for the next steps. This could get challenging projects for diaphragm walls in dams.
Stop ends fixing
Installing temporary stop ends at the bottom of the trench to prevent concrete from flowing out during placement.
Reinforcement Cage lowering
Lowering and placing a steel reinforcement cage into the trench, providing strength to the diaphragm wall.
Placing of Concrete
Pouring concrete into the trench, filling it to the required level and ensuring proper compaction and removing air bubbles from the concrete using a vibrator.
Withdrawal of Stop ends
Removing the temporary stop ends after the concrete has cured sufficiently.
Excavation and Anchoring
Excavating the area behind the completed diaphragm wall and installing anchors or supports if necessary for stability.
Stressing and Final Level of Excavation
Applying stress to the anchors and adjusting the final level of excavation to ensure the desired structural integrity and ground stability for diaphragm wall construction.
Quality control measures during diaphragm wall construction
Quality control measures during diaphragm wall construction in India involve several important steps:
- Material testing ensures that concrete and reinforcement bars meet the required standards. Tests include slump tests and strength tests for concrete and checks for dimensions and properties of reinforcement bars.
- Excavation control monitors the dimensions and verticality of the wall, using inclinometers and surveying equipment.
- Reinforcement installation is inspected to verify the proper positioning and alignment of reinforcement cages. This becomes all the more crucial in projects involving diaphragm walls in dams.
- Tremie concrete placement is supervised, checking flow rate and consistency and conducting slump tests and temperature monitoring.
- Wall construction is visually inspected for defects and includes non-destructive testing techniques.
- Concrete curing is carefully managed to optimise hydration and check on strength development.
- Backfilling and groundwater control are implemented using appropriate techniques and materials and groundwater levels are monitored.
- Documentation includes maintaining records of quality control activities, test results, inspections and any deviations or corrective actions.
These measures taken by diaphragm wall construction contractors in India ensure compliance with specifications, standards and regulations, ensuring the diaphragm wall’s integrity and durability.
What are the different types of diaphragm walls?
Diaphragm walls are typically classified into four types
Slurry diaphragm walls:
The most common type of diaphragm wall, slurry diaphragm walls are constructed by excavating a trench and filling it with a bentonite slurry. You will commonly find this form of diaphragm wall construction in India.
Grabbed diaphragm walls:
These walls are used in hard soil or rock conditions and are constructed by excavating a trench using a mechanical or hydraulic grab or cutter. These are usually used in metro diaphragm wall construction.
Sheet pile wall embedded in the cut-off wall:
Sheet pile walls are constructed by driving sheet piles into the ground along the groundwater table. The sheet piles are then connected to a cut-off wall, which is typically a slurry diaphragm wall in dams.
Composite wall panels:
Composite wall panels are typically used in shallow excavations and areas with limited space. Such basement diaphragm walls are used while constructing buildings in cities with narrow spaces.
Advantages of diaphragm walls
The diaphragm wall construction offers several advantages over other wall construction methods.
- Compared to a secant wall, it has fewer joints, which enhances water tightness.
- It also has exceptional strength, which makes it ideal for supporting deep excavations. The construction process is quiet and vibration-free, minimising noise and disturbance.
- Diaphragm walls can be constructed to great depths, exceeding 80m, and can be built using various types of rocks and soil.
- As a watertight structure, it minimally impacts surrounding structures as there is no need for dewatering.
- Additionally, the wall serves as both the foundation for the superstructure and the exterior wall for the basement, providing a multi-functional solution.
These advantages make diaphragm walls constructed by HIPL – a diaphragm wall construction company and an RMC supplier in India – a preferred choice in many large-scale civil engineering projects where structural integrity, water-tightness and versatility are essential considerations.
Solutions we provide
The construction of basement diaphragm walls in India is gaining momentum and we provide solutions to cater to the same.
Diaphragm wall construction in congested spaces: Diaphragm walls are used to create strong, impermeable barriers in congested areas. They involve excavating a trench and installing interlocking concrete panels or slurry walls. Diaphragm walls provide structural support, prevent groundwater ingress and are used in deep excavations like basements and tunnels. This solution optimises land usage and ensures stability of nearby structures.
Soil management: Soil management minimises soil movement and settlement near existing structures. It involves monitoring soil conditions, using appropriate foundation systems and implementing ground improvement techniques. Proper soil management safeguards neighboring buildings during excavation and construction.
Advanced excavation rigs: These rigs enable timely and effective project execution. They offer high-performance capabilities, precision and versatility. Casagrande rigs perform excavation and foundation works, including digging, drilling and pile driving. Their hydraulic systems, telescopic booms and rotating heads allow for efficient operations in different soil conditions. These rigs enhance productivity, reliability and adherence to project schedules while maintaining quality standards.
The solutions offered by HIPL, a leading construction company in India, ensure efficient and reliable execution of projects while prioritising land optimisation, structural stability and maintaining high-quality standards.
Common uses of diaphragm walls
Diaphragm wall construction is versatile and effective for various civil engineering projects, such as:
Deep basement excavation:
Diaphragm walls support deep excavations in soft or unstable ground, such as basements for high-rise buildings, underground parking garages, and metro stations.
Water cut-off:
Diaphragm walls create a watertight barrier to prevent water infiltration or seepage. The diaphragm wall in dams and reservoirs is crucial.
Ground improvement:
Diaphragm walls improve the load-bearing capacity of soft or unstable ground, such as foundations and roads.
Environmental protection:
Diaphragm walls contain contaminated soil and groundwater, or prevent the spread of pollutants.
Frequently Asked Questions
Yes, diaphragm walls are typically watertight when constructed properly. They are made of concrete, which is a very watertight material. In addition, the joints between diaphragm wall panels are sealed with water stops to prevent water infiltration. Diaphragm walls are often used in top-down construction, where the basement floors are constructed as the excavation progresses. This means that the diaphragm walls must be watertight to prevent water from entering the basement during construction. Diaphragm wall in dam projects also require waterproofing to prevent water seepage and erosion of the dam structure.
Diaphragm wall construction can be expensive. Diaphragm walls can only be used in relatively soft soils. If the soil is too hard, it will be difficult to excavate the trench for the diaphragm wall.
The minimum thickness of a diaphragm wall depends on the soil conditions and the height of the wall. In general, the thickness of a diaphragm wall should be at least 0.5 meters (1.6 feet). However, in some cases, the thickness may need to be even greater.