Built in 1540 AD, the Cabo Fort is the official residence of the Governor of Goa.
The
fort is located on Cabo Hill at a height of 40 m above the sea. It is a
two-storied monumental structure constructed with 0.7 m thick walls
comprising of laterite blocks in mud mortar.
The hill slope was
reported to have undergone gradual distress due to natural processes
over several decades with cracks appearing on the asphalted pavement in
front of the Chapel and on the floor of the verandah. The parapet wall
constructed around the edge of the steep slope adjacent to the fort had
also developed cracks at many places indicative of horizontal and
lateral movement.
Parts of the slope were stabilized by using
pre-stressed cables to tie up fractured media and by installing shear
interceptors using micro piles. Vertical sand piles were also installed
to release possible ground water pressure. The toe of the slope was
stabilized with retaining walls.
To monitor the distressed
unstable slopes of the Cabo Hill, GSI recommended field monitoring
through instrumentation. The instrumentation scheme included monitoring
of slope movement, settlement, water pressure and ground cracks.
Encardio-rite
was entrusted with the task of monitoring and instrumentation. While
implementing the instrumentation system, steps had to be taken to ensure
no structural damage was incurred.
Strengthening measures were devised for the slope foundation and the Fort’s structure, using Encardio-rite instruments.
Encardio-rite’s
instrumentation is still providing data online to the relevant
authorities. The scope of work included the supply of instruments,
installation, manual and automatic monitoring and setting up a web data
management system.
Instruments used included an in-place
inclinometer, borehole extensometer, piezometers, crack meters, joint
meters and automatic data loggers. An experienced and proficient
instrumentation and monitoring team provided installation and
commissioning services. A combined report for both manual and online
data was provided on a monthly basis. Monitoring reports included
interpretations of variations observed in the data, mentioning the
factors likely to affect the behavior.