International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 12 Issue: 10 | Oct 2025
p-ISSN: 2395-0072
www.irjet.net
Case Study on the Geotechnical Investigation for Pavement Rehabilitation of Karyambadi–Pulpally–Kenichira Road, Wayanad District in Kerala Akhil Paul1, Dr. M S Nagaraja Gupta2 1PG Scholar, Dept. of Civil Engineering, EWIT, Bangalore 2Professor and Head, Dept. of Civil Engineering, EWIT, Bangalore
---------------------------------------------------------------------***---------------------------------------------------------------------
Abstract - The Karyambadi–Pulpally–Kenichira Road in
Conventional overlay or resurfacing methods are inadequate in such terrains, as they do not address the fundamental issue of weak subgrade support. High rainfall in Wayanad, exceeding 6,900 mm annually, causes water ingress, swelling of clayey soils, and erosion of lateritic layers, which accelerate pavement distress (IMD, 2020). Previous studies have demonstrated that road failures in tropical and highrainfall environments are closely associated with soil plasticity, poor drainage, and inadequate pavement thickness [3]. To ensure durable rehabilitation, it becomes essential to investigate the geotechnical characteristics of the underlying soils and to design pavement and foundation systems based on site-specific data rather than generic assumptions [4], [5].
Wayanad district, Kerala, serves as a vital corridor linking remote rural settlements to the broader state highway network. Over time, this stretch has undergone significant deterioration due to ageing pavement, heavy monsoonal rainfall, and weak subgrade conditions. This study presents a comprehensive geotechnical investigation undertaken to provide reliable design inputs for pavement rehabilitation using Bituminous Macadam (BM) and Bituminous Concrete (BC). Fieldwork included nine boreholes, Standard Penetration Tests (SPT), pavement condition surveys, and the collection of soil samples. Laboratory testing comprised grain size distribution, Atterberg limits, compaction tests, specific gravity, shear strength, and California Bearing Ratio (CBR) analysis. Results indicated a heterogeneous subsoil profile dominated by clayey sands, silty clays, and lateritic soils, with medium to high plasticity and high optimum moisture contents. Soaked CBR values at several locations were below 5%, classifying the subgrade as weak under IRC: 37–2018 guidelines. Structural recommendations include conservative pavement design with thicker sub-base and base layers, pile foundations for bridge locations underlain by weak clays, and enhanced drainage systems to mitigate moisture-related failures. The findings provide critical guidance for designing durable, cost-effective, and sustainable road infrastructure in high-rainfall hilly terrains.
This study presents the results of a comprehensive geotechnical investigation carried out along an 8.6 km stretch of the Karyambadi–Pulpally–Kenichira Road. Field investigations included borehole drilling, Standard Penetration Tests (SPT), and pavement condition surveys. Laboratory tests determined index properties, compaction behaviour, and California Bearing Ratio (CBR) values. The findings provide critical input for pavement rehabilitation, foundation recommendations for retaining walls and bridges, and drainage design, ultimately ensuring the longterm performance of this vital rural corridor [6],[8].
1.1 Literature Review
Key Words: Geotechnical investigation, Subgrade strength, CBR, Pavement rehabilitation
The strength and durability of the underlying soils strongly govern the performance of road pavements. Several researchers have highlighted that weak or highly variable subgrades are the primary causes of premature pavement distress. Boboc et al., [3] emphasised the significance of geotechnical investigations in rehabilitation projects, noting that accurate subsurface characterisation is essential for identifying problematic soil layers and determining appropriate structural solutions.
1. INTRODUCTION Road networks play a vital role in enhancing connectivity, promoting trade, and supporting socio-economic development, particularly in rural and hilly regions. In Kerala, where agriculture and tourism dominate the economy, reliable road infrastructure is essential for the mobility of people and goods. The Karyambadi–Pulpally– Kenichira Road in Wayanad district is a critical corridor linking remote settlements to the state highway network. However, this stretch has undergone significant deterioration over the years due to heavy rainfall, poor drainage, and subgrade failure, resulting in alligator cracking, potholes, and unsafe riding conditions [1], [2].
© 2025, IRJET
|
Impact Factor value: 8.315
Lateritic and clayey soils, which are widely distributed across tropical regions, have been extensively studied in the context of pavement construction. Amadi et al., [4] investigated lateritic soils in Minna, Nigeria. They concluded that while these soils could provide satisfactory strength when well compacted, their high plasticity and moisture sensitivity
|
ISO 9001:2008 Certified Journal
|
Page 258