HYDERABAD: Can an ancient civil engineering technique be used in the modern era for developing earthquake-resistant buildings?
A team of civil engineering researchers from Hyderabad are studying the Kakatiya dynasty-era ‘sandbox’ technique of laying foundation to make a building earthquake-resistant.
The ‘sandbox’ technique was quite unique to Kakatiya dynasty and was used by Kakatiya rulers for construction of the famous Ramappa Temple and the Thousand Pillar Temple in Warangal. And the two temples, which are unaffected by seismic disturbances for hundreds of years, now stand testimony to the effectiveness of that technique.
The technique involved filling the pit — dug up for laying foundation — with a mixture of sand lime, jaggery (for binding) and karakkaya (black myrobalan fruit), before the buildings were constructed on these ‘sandboxes’.
Dr Venkata Dilip Kumar Pasupuleti, Assistant Professor, School of Engineering Sciences at Mahindra Ecole Centrale in Hyderabad, who is leading the study on the ‘sandbox technique’ for the last one and a half years, told Express: “The sandbox in the foundation acts as a cushion in case of earthquakes. Most of the vibrations caused by earthquake lose their strength while passing through the sand by the time they reach the actual foundation of the building.”
“Although techniques similar to sandbox have been found to be employed in other parts of the world but usage of sand is probably unique to Kakatiya dynasty as in other places mud or stones were to be used,” he added.
Sandbox technique is not being used anymore but Dr Pasupuleti feels confident that it can be used even now, for making concrete buildings earthquake-resistant and that sandbox technique is even long-lasting and more beneficial than the modern techniques. He said that presently, Elastomeric Base Isolation technique is used in making a building earthquake-resistant as part of which rubber is used in the foundation which gets worn out in a span of 30 to 40 years and needs more maintenance.
However, in sandbox technique sand is used, whose weathering rate is very slow, as a result it can last for hundreds of years as is evident in the case of Ramappa or Thousand Pillar temples. Moreover, the process of laying sandbox foundation will also be more economical and it will be naturally available.
The sandbox technique, however, has its limitation that it cannot be used in construction of tall buildings like skyscrapers though it can be easily used in shear-predominant structures, which are the most common form of buildings in India.
Dr Pasupuleti said that the use of sandbox technique will be beneficial for construction of houses in earthquake-prone zones in the country. “However, much more research work and standardisation is required to be done for using the sandbox technique in construction. As of now, only preliminary experiment of just the sandbox has been carried out in laboratory by him and his team by building a small prototype of sandbox,” he said.
It was observed that almost 60 per cent of the impact force of vibrations was reduced after passing through a sandbox with dry sand. The results of this experiment have been published in a research paper, selected for presentation in International Conference on Digital Heritage, Euromed 2018 in Cyprus next week.
Dr Pasupuleti’s team will soon be developing 3D computer models of the Ramappa and Thousand Pillar temples, and check efficacy of sandbox technique.
‘Sandbox’ technique flourished during Rudrama Devi’s rule
Hyderabad: ‘Sandbox’ technique flourished during Rudrama Devi rule. It was in the early 12th century, under the rule of Rudradeva Maharaja of Kakatiya dynasty, popularly known as Rudrama Devi, the civil engineering technique of ‘sandbox’ came into usage for developing foundations in construction of buildings.
SS Rangacharyulu former archaeologist with the Telangana archaeology department said: “As per historical records, the Kakatiya dynasty used to be subordinate to other dynasties, like western Chalukyas. Rudradeva Maharaja was the first sovereign independent ruler of the Kakatiya dynasty, under whom the ‘sandbox’ technique started to flourish.” “Thousands of temples constructed thereafter, including the Ramappa and Thousand Pillar temples in 1213AD and 1163AD respectively, were built using ‘sandbox’ foundations,” he said.