Rlys to use woven geotextile, geogrids toprotect embankments from soil erosion

Source: The Hitavada      Date: 06 Dec 2018 12:17:13


 

By Sagar Mohod,

In first phase, SECR will cover a 7.91 km patch on Bhandara Road (in Nagpur-Tumsar section) and another portion in Salwa-Chacher section with coating of yarn

EVEN as society is increasingly shunning usage of plastic, one of its superior forms has found good use in Indian Railways,helping in protecting the earthen embankments from erosion. The technological innovation is thermoplastic polymers that are boon in area having embankments made up of black cotton soil.

Here Geotextiles and Geogrids are being put to effective use, specially in South East Central Railway’s Nagpur Division that have large formations of black cotton soil. One particular 55 km patch in Bhandara district (on Nagpur Tumsar road) is very troubling for railwaysas trackgeometry gets disturbe as the embankment of black cotton soil weakens frequently.

A 7.5 km stretch is now being patched using the polymers as black cotton soil weakens owing to expansion on absorption of water and shrinks during summer This is the natural tendency of black cotton soil owing to which track parameters are often disturbed affecting movement of trains, said officials of engineering branch. Railway Design and Standards Organisation (RDSO), after extensive tests, rolled out the specification for usage of woven geotextile and geogrids that are found to strengthen the embankments.

Since they are affixed on embankment below ballast with help of Ballast Cleaning Machine (BCM), it has another advantage as deep screening exercise is also simultaneously conducted thereby adding another layer of safety. SECR has identified one particular patch of 7.91 km on Bhandara Road (in Nagpur-Tumsar section) and another portion in Salwa-Chacher section for covering with coating of yarn in first phase. The exercise is part of upgradation of track infrastructure to meet future demands in backdrop of increasing rail traffic and speed of trains. The main advantage of protecting track parameters is that it would bring down cost of track maintenance.

The technology in use is woven geotextile made from polypropylene multifilament yarn, the technical term for the polymer. Apart from incurring recurring expenditure, the time wasted due to blocking railway path for undertaking repair works is also loss in earnings. But with usage of polymer and geo textiles, railway engineers have found good results in keeping intact embankment for longer periods. This in turn keeps track geometry unaltered for extensive time frame.

In layman’s term, one can call it a fabric that prevents absorption of water by the earth below the track. Railway engineers said that most of the earth formations date back to time of Britishers and hence they require frequent tamping, an exercise wherein the soil formation is restrenthened every six month as per norms. However, owing to increase in train operations and loads the time of undertaking tamping exercise has shortened.

Now, after every three or four months, a major block is taken in the identified track section that undergoes correction in its geometry. However, with usage of geotextiles and geogrids, the maintenance period has increased which is a big relief for railways. Since the geotextile underneath ensures that water is drained out from actual tracks the shape of embankment does not gets disturbed.

A senior engineering officials said that they were fed up of regular tamping as it ultimately affects punctuality as blocks are required for the exercise. “Since this is the first time we are using the layers of geotextiles and on top of it geogrids our fingers are crossed. During the monitoring period, if feedback is as expected then the polymers would be rolled out in maximum troublesome sections of division,” the officials said while sharing details of the plan with ‘The Hitavada’.