Senthil Kumar V

Department of Chemistry

School of Advanced Sciences

Vellore Campus

Chandrasekaran S-S

Department of Structural and Geotechical Engineering

School of Civil Engineering

V. B. Maji

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Overview of Rainfall Induced Landslide Events and Importance of Geotechnical Investigations in Nilgiris District of Tamil Nadu, India

Advancing Culture of Living with Landslides

The present study investigates the rainfall-induced long-runout landslide that occurred in the Achanakkal area of the Nilgiris district in the Tamil Nadu state of India on November 11, 2009. The landslide damaged a house located on the runout path and killed its eight residents. The slide also damaged a road network, affecting traffic for several weeks. The main objective of the study is to understand the failure mechanism associated with Achanakkal 2009 landslide. This study is composed of a field investigation, laboratory experiments, and a numerical simulation of the landslide. Based on the field investigation including a topographical survey, a borehole investigation, a geophysical test, and laboratory classification tests, the slope geometry was identified and the subsoil was characterized. Ring shear tests were performed to estimate the shear strength parameters such as peak and residual friction angle (φp and φm) and steady-state shear resistance (τss). Numerical simulation of the landslide was carried out using the LS-RAPID landslide simulation model by incorporating the shear strength parameters obtained from the ring shear tests. The simulation results reproduced the failure mechanism of the Achanakkal landslide and matched the runout distance, landslide boundary, and distribution of debris mass that were observed from the topographical survey well. The analysis results revealed that the rainfall infiltration due to 5 days' antecedent rainfall of 594 mm; a very large amount of daily rainfall, 820 mm, on the event day; and accumulation of rainwater on the source area charging from the above plateau due to blocking of drainage culverts increased the soil saturation. An increase in saturation level of the soil developed the pore water pressure in the source area. The development of pore pressure to ru=0.5 significantly reduced the shear resistance of the soil at the slip surface from the peak value to the residual value along with shear displacement was the possible cause for triggering of Achanakkal landslide. The analysis also revealed that the simulation model initiates the landslide at a smaller pore water pressure ratio than the limit equilibrium method of stability analysis due to progressive failure. © 2019 American Society of Civil Engineers.

Journal of Geotechnical and Geoenvironmental Engineering

Failure Mechanism of Long-Runout Landslide Triggered by Heavy Rainfall in Achanakkal, Nilgiris, India

Rainfall-induced landslides are common natural hazards in tropical regions. The present study investigates a rainfall-induced landslide that occurred in 2009 in theMarappalam area of Nilgiris district, Tamil Nadu, India. It was triggered by a high-intensity short period of rainfall that occurred after a prolonged low-intensity rainfall at Marappalam. The effect of rainfall infiltration on the unsaturated residual soil slope was investigated by transient seepage analysis using the finite difference method. The fluid-mechanical interaction of unsaturated soil has been obtained using coupled fluid flow analysis. The analysis was carried out in two stages. The first stage saw prolonged low-intensity rainfall of 710mm over 8 months. The second stage showed a short-duration, high-intensity rainfall of 719mm in just 10 days, which caused a landslide in Marappalam. It was observed that the first rainfall event saturated the Marappalam slope to a degree of saturation of 0.6. The saturation level increased during the second rainfall, which advanced the wetting front to the lower layer of the Marappalam slope and saturated the slope to the degree of saturation of 0.8. The wetting front reached the soil-rock interface at the end of the second rainfall event, increasing soil saturation and seepage force, accompanied by reduction in matric suction and the subsequent development of positive pore water pressure. The development of positive pore water pressure decreased the effective stress, thus reducing the shear strength of the soil along the soil-rock interface, causing landslide in Marappalam. The study also described the relationship between rainfall and landslide occurrence based on daily and antecedent rainfall in conjunction with past landslide events occurring in the Marappalam region. The rainfall-threshold relationship provided the optimum level of daily and 5-day antecedent rainfall required to trigger landslides in the Marappalam region, which can be used for early warnings at the regional level. © 2018 American Society of Civil Engineers.

International Journal of Geomechanics

Rainfall-induced landslides: Case study of the Marappalam landslide, Nilgiris district, Tamil Nadu, India

India is among the top ten countries with the highest percentage of landslide fatalities for the past few years. Intense rainfall during the 2009 monsoon in the hilly district of Nilgiris, in the state of Tamilnadu in India, triggered landslides at more than 300 locations which affected road and rail traffic, destroyed buildings, caused the death of more than 40 people and left hundreds homeless. In this paper, three case histories from Nilgiris district are investigated: the slope failure of a railway track at Aravankadu, failure of retaining walls supporting buildings at Coonoor, failure of the slope and retaining wall along national highway (NH67) at Chinnabikatty. Laboratory investigations are carried out on soil samples collected at these sites. Soils at all the three locations have high fine content and low values of coefficient of permeability. Finite element analyses of all the three case histories were carried out using PLAXIS2D software in order to understand the failure mechanism and contributing factors. Slope stability analysis using strength reduction technique is carried out for the slope at Aravankadu to determine the critical slip surface and factor of safety. Results reveal that the increase in pore pressures led to a reduction in shear strength of the soil and consequently resulted in progressive failure of slope at Aravankadu site. Displacement analysis is carried out for Coonoor and Chinnabikatty sites. The results show that combined effect of surcharge load of building and high pore pressure led to intense shearing behind the retaining walls at Coonoor site. Results indicate occurrence of large displacements along the face and at toe of the slope at Chinnabikatty site. © 2012 Springer Science+Business Media Dordrecht.

Natural Hazards

Investigation on infrastructural damages by rainfall-induced landslides during November 2009 in Nilgiris, India

Landslides

The Varnes classification of landslide types, an update

Quantitative assessment of landslide hazard along transportation lines using historical records

MSOR Connections

Mathematics Portal Project

Polar Research Board annual report, 1987 and future plans

Journal	Data powered by TypesetAdvancing Culture of Living with Landslides
Publisher	Data powered by TypesetSpringer International Publishing
Open Access	0