: Are the builders keen on taking advantage of realty boom giving a go-by to the standard procedures of soil strengthening? In the backdrop of the tragic incident in which seven young lives have been snuffed at the site of an under-construction shopping complex, structural engineers have raised concerns over strength of high-rise structures coming up in a big way here.
“The soil type varies from place to place and we know in Hyderabad, high-rise buildings have been built on hard and rocky soils which can withstand lateral pressure. But in Guntur and Vijayawada, we have predominantly black cotton soil which makes it mandatory to go for soil strengthening. It is quite an expensive procedure but one has to keep in mind the safety of the structure,’’ said senior structural engineer Anjaneya Prasad.
Mr. Prasad, who has assisted in the construction of a shopping mall in Vijayawada, said that builders there had spent close to Rs .4 crore on soil strengthening alone.
The major issue the builders face is building the retaining wall where soil strength is low.
“One has also to consider the strength of adjacent properties and if the soil strength is weak in the adjacent properties, it weakens the soil at the site too,’’ he said. Over the years, the engineers have adapted various soil strengthening techniques such as soil nailing, piling, micro piling and building diaphragm walls etc.
Soil nailing tech
In the soil nailing technique, the soil near the retaining walls is strengthened by embedding rods horizontally into the soil reinforcing the soil and iron.
Apart from soil strengthening, one has to keep in mind the setbacks also.
A minimum setback of 3 metres should be left for structures with double cellar, engineers say.
This apart, engineers say that one should have a technical soil strengthening agency to address the issue. Usually, the assessment of soil strength is being done by the Civil Engineering Department of engineering colleges, but considering the demand for high-rises in the Capital region, the demand for professional agencies is on the rise.
