Statue of Unity : An Engineering Marvel
An iconic 182 meter tall statue, a tribute to the Iron Man of India, is being built at the Sadhu-Bet Island, approximately 3.5kms south of Sardar Sarovar Dam at Kevadia in the Narmada district of Gujarat This inspiring memorial site, with a number of edutainment components, is located between the Vindhyachal and Satpuda Ranges rising weir Narmada River, impounded by Garudeshwar, the Sardar Sarovar Dam and the town of Kevadia. The majesty of this grand monument will be enhanced by a picturesque backdrop. Its unique location will prove to be beneficial for eco-tourism and regional development.
Features of Sardar Patel Statue
- An exhibition centre at its base showcasing the life and achievements of Sardar Patel
- A 320 m long designer bridge connecting Sadhu Hill to the mainland
- A memorial and visitors’ centre
- 4-lane approach road
- An administrative complex, 3-star hotel and conference centre
- A 40-m suspended fabric roof structure for the visitors’ centre
1. Site Location
The Statue of Unity stands firmly atop a sturdy rock formation along the shores of the Narmada River in the Indian state of Gujarat. Located approximately 90 kilometers to the south of Vadodara city and positioned about 3 kilometers downstream from the Sardar Sarovar dam.
2. Geology of the site
- The site of the statue is situated on the banks of the Narmada River, which is one of the major rivers in India.
- From a geological perspective, the area surrounding the Statue of Unity is situated within the Deccan Plateau, an expansive volcanic plateau located in the western and central regions of India. This plateau is predominantly comprised of layers of lava flows and various volcanic rock deposits, which accumulated over countless millennia. The genesis of these volcanic rocks can be traced back to the Cretaceous and Paleogene periods, resulting from the significant volcanic eruptions that occurred in this particular geographical area during those epochs.
- The Narmada River, flowing near the Statue of Unity, has played a significant role in shaping the landscape over geological time. The river has eroded through the volcanic rocks, creating a gorge and exposing various geological formations along its course.
3. Foundation of Statue of Unity
- The mound upon which the statue was erected exhibited numerous fracture planes. To ensure the secure establishment of the foundation, these fracture planes underwent a process of treatment involving the injection of grout and the installation of grouted anchor rods.
- The hillock was flattened to create a stable base for the statue’s foundation mat. Since the mat is supported by solid bedrock, there was no need for a pile foundation. Instead, grouted rock anchors were employed to mitigate localized tension.
- The foundation experienced significant tension due to lateral loads causing overturning moments. To counteract these forces, rock anchors were installed deep into the rock and tensioned at the foundation level to provide resistance.
- According to the findings from the site investigation, the average bearing capacity of the rock was determined to be 2300 KN/m2, demonstrating that it is more than adequate to support the statue.
- A self-compacting concrete with an M60 grade was employed for the mat foundation. Moreover, the temperature during the concrete placement for the mat foundation was carefully controlled within the range of 18°C to 22°C.
- A polythene sheet was used to cover the surface area of the mat foundation, and on top of the sheet, a 100 mm layer of dry sand was applied. This was done to prevent the occurrence of thermal variations.
- A total of 4354 cubic meters of concrete was employed in the construction of the primary raft. This significant undertaking was accomplished through a continuous pouring process that lasted for 132 consecutive hours.
- Throughout the constant pouring of concrete in the raft, two on-site batching plants were continuously used to produce concrete. The positioning of concrete was done by a mix of fixed pumps. Additionally, concrete was pumped horizontally for 420 m through a 125 mm sized steel pipeline.
Brainchild of Larsen & Toubro
L&T Ltd, a multinational conglomerate that provides EPC (Engineering, Procurement, and Construction) services, high-tech manufacturing, and other services, was awarded the contract for the Statue of Unity project, valued at ₹2,989 crore. L&T oversaw the design, planning, and execution of the project, mobilizing a workforce of over 4,000 laborers and 250 engineers who worked tirelessly to complete the project in a record-breaking 33 months.
The statue highlights a viewing gallery at the 153-meter altitude, which can hold up to 200 people at a time. It offers a breath taking view of surrounding mountain ranges and the Narmada river.
•The core of the statue has gobbled up 210,000 cubic metres of cement concrete, 6500 tonnes of structural steel, and 18500 tonnes of reinforced steel.
•The outer facade consists of 1700 tonnes of bronze plates and 1850 tonnes of bronze cladding in the form of 565 macro and 6000 micro panels
The Struggle
•The location
•Finding proper concrete strength
•Irregular structure
•Work during the monsoon
•Durability
•Natural factors like wind earthquake as the statue is Situated right in the middle of the river Narmada
Structural System of Statue of Unity
i. Base of the Statue
The following points describe the base of the statue:
1.The base of the statue is a shallow foundation (raft foundation) that sits on a strong rock.
2.The base is between 45 and 52.5 meters above sea level.
3.The ground floor of the base is at 58 meters above sea level and is made of structural slabs supported by columns and walls.
4.From 58 to 83 meters above sea level, the base is made of both concrete and steel.
5.The slabs at 78 and 83 meters above sea level, as well as the inclined roofing, are made of composite deck slab resting on structural beams and trusses.
ii. Core Walls
The following points describe the core walls of the statue:
- The statue’s two main vertical core walls are oval-shaped and measure 11.30 meters by 8.40 meters.
2. The elliptical core walls are 154 m high with openings for lift lobby and fire stairs.
3. The core wall basically starts from +56.575 m level and continues up to +209.50 m level.
4. The coupling wall is linked to the core walls from +115.0 m level to +193.0 m level.
5. Core walls are confined by an external oval concrete wall up to the podium level at +83 m.
6. Above the podium level, where the statue’s facade begins to take shape, two reinforced concrete (RC) walls, known as coupling walls, connect the two core walls for their entire height.
7. The thickness of the core wall is continuous throughout the height, whereas the thickness of the coupling wall varies from 0.55 m to 1.33 m.
8. The elliptical shape of the core wall was achieved by bending the rebar of 32 mm diameter around the core wall.
9. The core walls were constructed with a self-compacting concrete (SCC) of M65 grade.
Construction Sequence
The construction process of the Statue of Unity was made as simple as possible. The composite core construction follows a methodology that is typically used for composite columns and walls in tall buildings. The suspended truss frame was either welded or bolted to core walls.
The construction sequence of the world’s tallest statue is described below:
- The fracture planes of hillocks were treated via grout injection and grouted anchor rods.
2. Levelling of the hillock was done in order to construct the mat foundation.
3. After that, the casting of the raft foundation was done.
4. Structural steel of shape W-360 was embedded in the composite core walls.
5. The W-360 shapes of structural steel were then connected with the internal bracing of the 150 mm x 150 mm (6” x 6”) angles.
6. After the structural steel was erected 5–10 m above the foundation, the casting process of the cores began.
7. Further, the structural steel truss frame was erected from the concrete cores. For this process, W-360 steel shapes were shop-welded to the internal steel shapes in the cores.
8. Internal steelwork was continued and followed by the casting of the cores.
9. Following that step, the bronze-clad panels were affixed to the truss frame. To achieve this, the outer surface of the structural truss frame was joined through welding to a steel subframe. This subframe was interconnected with the clad panel to provide support for the cladding system’s weight and to withstand both seismic and wind forces. Additionally, the clad panels were specifically designed to incorporate overlapping sections, enabling both vertical and horizontal movement of the panels.
10. The above process was repeated until the completion of the statue.
Tourism:
Over 128,000 tourists visited it in 11 days since it was opened to the public on 1 November 2018. Buses take tourists from the parking lot to the statue, as the area around the statue is a “no private vehicle” zone. Elevators run from 3 to 5 pm to take tourists with tickets up to the observation deck at the top. The statue remains closed every Monday for maintenance.
Conclusion:
Statue of Unity is truly an engineering marvel. It is a tribute to Indian engineering skills. Our skilled labourers, architects and engineers have received immense appreciation for constructing this intricately designed enormous piece of art. Statue of Unity is a symbol of unity and strength. It reflects the true personality of Sardar Patel who was strong and robust. PM Modi sees this statue as an inspiration for the people of our country.
References:
- Mr Sandeep-Ghan http://www.igs.org.in
- SELP Journal of Social Science Volume XI, Issue 45, July — September 2020
- https://theconstructor.org/case-study/statue-of-unity-structural-construction-features/61410/
Author : Lokendra Singh Rathore
