Slope Protection and Retention Work

Slope Protection & Retention work using Gabion Gravity Retaining wall & Non Woven Geotextile at CWA-NGP Gauge conversion project of South Eastern Central Railway.

Introduction :

Execution of Slope Protection work (Project executed between August 2019 to May 2020) for deep cutting between major bridge no 83 and 84, plus protection work of major bridge no. 83. in section between Bhandarkund to Bhimalgondi in mega block to make the section fit for commissioning in connection with Chhindwara-Nagpur Gauge Conversion Project.

Quantity – 21000 Cubic Meter

Challenges :

The entire line passes through ghat sections and work of 20km stretch between Bhimalgondi-Bhandarkund was most challenging due to its difficult terrain with sharp curves, hills and high intensity rainfall. The stretch had one 45-metres high bridge, 26 big and 275 small bridges and two tunnels of 700 metres and 120 metres each.

Deep Cutting for tunnelling and major bridge of height 45m caused steep slope with loose soil and debris. Since this is a heavy rainfall area, loose soil and dampness beneath the railway track was a persistent problem. High intensity rainfall on steep slopes causes loss of top soil resulting in collapsing of slopes due to weak self-retainability of the earth thereby contributing to geotechnical hazard, which could cause derailment that had the potential for life and economic loss.

Proposed Solution :

The problem being persistent and having larger socio economical impact required a concrete, permanent and a long-term solution. In line with our belief of identifying the issue and then designing, developing and implementing high quality affordable solutions, we suggested the application of Double Twist Hexagonal Shape Gabion Box and Non Woven Geotextile to address the issue from its core. This solution also complied with RDSO’s (Research Design and Standard Organisation) specification. 

Before application, profiling of the area, soil testing and other technical matters were assessed thoroughly.

Why Gabion Box & Non Woven Geotextile was used?

Non Woven Geotextile are chosen when both soil separation and permeability are required. Geotextile allows filtration of granular layers in applications like rail in this case. It has been characterized by high strength, maximum width and UV stabilized. It is resistant to commonly encountered soil chemicals, mildew and insects and is non-biodegradable.

Double Twisted Hexagonal Gabion Gravity Retaining wall structure is a gravity retaining structure which is flexible and permeable, it retains soil with it’s weight. The porosity of Gabions prevents the pore-water pressure development behind the walls which is one of the major advantages of these kinds of systems. These structures blend with the surroundings and allow vegetation to take roots through the structure which enhances the life of the structure. Reduced carbon foot prints are also a noticeable feature when compared to conventional solutions.

Both these product mix along with right implementation were just apt for solving the issue of soil erosion and retention.

Conclusion :

The project was successfully inspected and given a green signal by commissioner of railway safety (CRS of Southern and South Eastern circle) for 149km long broad-gauge railway line between Itwari-Chhindwara to Nagpur under South Eastern Central Railway (SECR). The upgraded line which now has a potential to run at a speed of 70 kmph was opened in late 2021. This line now becomes a full circle from Nagpur connecting the main Delhi line via Junnardeo.

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