A note on the structural system and progress at Dr. Bhavesh Dave’s residence at Kensville

The Kensville site is located just before the great marshes of Nalsarovar bird sanctuary on a natural drainage path, and therefore has a high water table. This geological / geomorphologic feature has led to foundation soil being dominantly of silty sand type. Approximately, seventy five percent (75%) of the soil is grainy and rest is highly shrinking clay. In colloquial terms*, the soil is also known as black cotton soil. The soil is highly draining in nature besides its average bearing capacity. This soil condition along with existing loads required us to consider a circular masonry foundation, on which the ferrocement shell and landscape grass composite would rest.  It is intended that enough integrity is achieved by the foundations and the superstructure shell independently, which then would account for differential movement conditions because of the soil. See the sketch below for details.

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Construction of this masonry foundation is complete and the floor plinth is being readied now.  Like other parts of the country, availability of qualified workforce is a concern, and the site’s remoteness keeps the pace of our work slow. However, our contractors Nirav and Dakshesh found local workforces proficient in brick masonry and excavation. Soon after completion of excavations, constant interaction with the brick masons, before starting the work and during execution, ensured desired quality.


For pictures click 


At present, mobilization of materials for construction of ferrocement shell is underway; and we will keep uploading information here as work progresses. Please keep visiting.

*black cotton soil is a local technical simlie for highly shrinking clay

18th September 2011 Earthquake

Update: 29th April 2012
The progress at Sangkhola school is slow but strong. The slow progress is largely due to non-availability of qualified workforce which can work with Reinforced Cement Concrete (RCC ) as a construction material. The State Education Department has also expressed its desire to construct new buildings using RCC only, and is keen that the work is completed at its earliest. It is well understood and established that the damage during this earthquake has been primarily due to badly retained earth, retaining walls, and inadequate designing, especially of RCC joints. In many cases the soil wasn’t properly compacted; in some cases soil has been just dumped from other places in creating levelled land and is therefore very loose, and retaining walls were inadequate for the soil and therefore the building they were supporting. Due to the insufficient loose foundation soil, the structures underwent more shaking and resulted in greater damage despite Sikkim’s buildings having relatively good construction quality. Inadequate attention to design therefore seemed to be an important reason for the extensive damage caused by the earthquake.

Now, with a revised project plan we are expecting foundation work to complete by mid May; and structural skeleton with other finishing works envisaged to complete by the middle of June. See pictures of the foundation work here, where present emphasis is on preparing highly compacted foundation trenches to support RCC column pedestals.

We are looking at building the local contractor's competency in both technical and managerial aspects of construction. This made us put more experienced engineering team on the ground with Rakesh from SEEDS in the lead now along with the mason Ramesh from Patanka village in Gujarat, to facilitate the re-construction of the school.

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In addition, preparations are underway for reconstruction of the damaged buildings in three school campuses in the East district of Sikkim. We are additionally looking at overall Life Safety in these school campuses for future extreme events, and improvement of the local built environment of through awareness building and community participation exercises.