BHOPAL: Engineers have attributed the reasons behind collapse of grade separator in Lalghati Flyover Bridge (FOB) to faults like faulty “soil compaction”, not mainting CBR (Soil’s Calibration Bearing Ratio) which should be 7 optimum and moisture.
National Highway Authority of India (NHAI) has sub-leted Flyover construction to petty contractors. On intervening night of Sunday-Monday, grade separator of the FOB collapsed.
Soil compaction is the process in which stress is applied to a soil causes densification as air is displaced from the pores between the soil grains, and moisture, which is directly linked to binding with panels and soil.
Soil’s Calibration Bearing Ratio (CBR) should be 7 which optimum. In geotechnical engineering, soil compaction is the process in which stress is applied to a soil causes densification as air is displaced from the pores between the soil grains.
Suresh Mishra, retired Superintending Engineering PWD, said, “Moisture content should be maintained. Pipe line passing through bridge should be removed as it increase moisture percentage which creates silts which happens to be pulpy. Secondly panel which is of fiber or metallic loses grip over soil with increase of moisture leading such collapse. Panels bind the soils in bridge. Thirdly, there should be proper compaction of soil. These are factors behind collapse of grade separators.”
Kapil Tyagi, another engineer, said, “Actually, petty contractors who were sub-let work by NHAI, hardly bother about observing norms.
They failed to maintain proper compaction and CBR ratio. They should maintain 7 CBR as it include soil texture and other things. Thirdly, there quality in entire process of construction was not up to the mark. This is reason, such kinds of incidences are happening with Lalghati Flyover Bridge.”
