Page 46 - DIGITAL ISSUE MAY 2018

GUEST ARTICLE ROAD & ROAD CONSTRUCTION EQUIPMENT

Slope Stability analysis of Reliance Power Transmission Tower – 61,
along Western Expressway, Mumbai.

On the express highway Reliance Energy consists of massive, vesicular, amygdaloidal depth of 45 and strength were measured
Ltd (REL) has numbers of towers located and weathered basalt. e rock types of the for selected samples. e results of resistivity
on hillocks along the road side. Due study area is fractured and jointed in nature. are given below.
to road widening work carried out by Basalts are moderately weathered but the A er all these tests and con rmation, again
MMRDA, these hillocks were excavated rate of weathering decreases from the a two dimensional numerical analysis has
and widened using explosive energy. ese bottom to top of the basement rock. Water been done and was found that the overall
operations have a ected the stability of seepages through fractured and jointed factor of safety from 1.86 to 2.19. This
hillocks. A study was carried out by IIT rock mass and vegetative covered found indicates that the slope is more stable than
Bombay in year 2008 for three towers at some part of the area. e geotechnical the earlier. e maximum shear strain rate
located at various locations i.e., Tower 53, field investigation has been carried out has drastically decreased a er treatment
61 and 62. IIT Bombay team has suggested along the road cut section to understand particularly at the height of 16m at the top.
few strengthening treatment for tower the geotechnical properties of the rock Location Factor of Safety
number 53 and 62 at the site which has mass. e rocks are jointed in some part of
been executed by REL. Prof. T N Singh the road cut section. Tower 61 1.86 (Before treatment)
of IITB along with Kunjjan Popat had The rock type in this location is dark Tower 61 2.19(A er treatment)
also suggested special chemical grouting brown to grayish in colour. e joints are
for tower number 61. REL has engaged uneven in nature. Sometimes bedrock Concluding Remark
TRIFIX to perform the job of chemical shows horizontal opening between two Present study indicates that the slope is
grouting at various vulnerable locations consecutive layers. Distinct lithological overall stable a er the treatment strain rate
all along the slope. e work had been contrast observed in this location where has been reduced. However, proper drainage
carried out using special injection grouting the rate of weathering decreases towards arrangement should be taken to avoid any
equipments and Polyurethane based the top . engress of water through fractures. It is
chemicals and completed in December Factor of Safety without chemical grouting generally true for any slope.
2008. A er the completion of the grouting was obtained 1.86 indicates that the
work REL consulted Department of slope at location of Tower 61 is stable but Artilcle is co-authored by Prof. Dr. T. N. Singh,
Earth Sciences IITB, for assessment of few locations indicates high strain rate Department of Earth Sciences, IIT Bombay
improvement in slope at tower number 61. particularly at the top of a slope Maximum and Kunjjan Popat, I.R.P (Germany),
Prof. T.N.Singh and his team conducted shear strain of 2.5e-05 has developed Triseal Technologies (LLP)
the eld investigation 2-3 times and taken along the failure surface. Hence, chemical
required measurements at the site to collect grouting was suggested to strengthening the
the data for assessment and evaluation of all fractures and weak zones to avoid further
stability of slope and it’s improvement a er widening as well as to prevent it from water
chemical treatment. ingress during rainy seasons.
Mumbai region is mainly occupied by To further confirm the soundness of
Deccan basalt flows and their acid and rock, a er treatment a vertical resistivity
basic variants. e area under investigation sounding survey was conducted at the Prof. Dr. T. N. Singh Kunjjan Popat

52 CONSTRUCTION OPPORTUNITIES|MAY 2018