© 2018 jetir december 2018, volume 5, issue 12 a case

© 2018 JETIR December 2018, Volume 5, Issue 12 www.jetir.org (ISSN-2349-5162)

JETIREB06136 Journal of Emerging Technologies and Innovative Research (JETIR) www.jetir.org 1147

A CASE STUDY OF KOTROPI LANDSLIDE IN

MANDI DISTRICT

Kapil1 and Neeru Kaushal2

Assistant Professor1,2, Lovely Professional University, Punjab, India

Abstract - Himachal Pradesh forming an important segment of Himalaya mountain system has experienced

many landslides and has been the focus of study for over hundred years. Landslides are also recognized as

Landslip, which is a type of mass wasting including a wide range of earth movements. This thesis includes the

assessment of landslide occurred at Kotropi village on 13th august 2017, this landslide is classified as debris

flow and failure mechanism was deep rotational failure. The main triggering factor was due to heavy rainfall

of current monsoon season, causing the third reactivation of Kotropi landslide since 1977 and 1997, about 46

people were dead in these shocking incidence.

Numerous experiments were done to overcome the landslide problem in the Kotropi region. On the sample,

standard Proctor test and direct shear test were performed. Initial investigation shows that soil was cohesion

less; its shear strength and maximum dry density were very low. Remedial measure are suggested as to

construct a permanent retaining wall followed by a bridge over the road alignment area for channelizing the

water coming from upslope areas, protecting the upslope areas with the help of plantation to bind up soil ,

Rock catches fences and Water drainage system in the crown area. The present study lays the basics for

further work in assessment of rainfall induced landslides in Himalayan region.

1. Introduction - A landslide is the motion of a mass of rock, particles, or earth down a slope, beneath the have an impact on of

gravity. Special phenomena purpose landslides, together with excessive or extended rainfall, earthquakes,

speedy snow melting, and a ramification of human sports. A variety of moves are associated with landslides

flowing, sliding, toppling or falling moves, and many landslides showcase a combination of or extra varieties

of moves (Varnes, 1978; Cruden and Varnes, 1996).

In India, about 0.42 million sq.km or 12. 6% of land area, excluding snow blanketed region, is at risk of

landslide risk. Out of this, 0. 18 million sq. Km falls in north east Himalaya, along with Darjeeling and Sikkim

Himalaya; 0. 14 million sq. Km falls in north west Himalaya (Uttarakhand, Himachal Pradesh and Jammu &

Kashmir); 0. 09 million sq. Km in western ghats and Konkan hills (Tamil Nadu, Kerala, Karnataka, Goa and

Maharashtra) and 0.01 million sq. Km in Eastern ghats of Aruku vicinity in Andhra Pradesh. The landslide-

prone Himalayan terrain falls within the most earthquake-prone zones (region-iv and v; bis 2002) wherein

earthquakes of modified Mercalli depth viii to ix can arise, and therefore, also are liable to earthquake-caused

landslides. Comparing and mitigating the landslide risk and threat is a first-rate undertaking for the

technocrats and selection makers inside the developing global as 80% of the suggested fatalities due to

landslide is inside the growing international locations.

In the Himachal region of India, land dreadful conditions are mainly caused by landslides and have developed

into a yearly habitual phenomenon. On 13th August 2017, a massive landslide took place at Kotropi on

National Highway-154, Padhar Tehsil, Mandi district, Himachal Pradesh. The landslide passed off on

countrywide toll road 154, the road among Mandi and Pathankot. Media reports suggest that a segment of the

collapsed definitely and two buses of Himachal kingdom delivery together with few other motors were buried

below the debris. As of now, information reviews advise that there had been 47 fatalities from the incident

(the Tribune…. 2017). Round 300 m of the motorway has been completely buried under debris, as a result

cutting of communication on a very important avenue.

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The Landslide happened in a time of extraordinary rainstorm precipitation that has activated Landslide over an

extensive swathe of the Himalayas in India and Nepal. News reports that the two transports had the stop for a

tea break when the landslide happened a brief time after midnight. The vehicles were cleared 800 m down the

slant and were covered by the debris. Geologically the area is in a trusted contact (important boundary thrust)

between the siwaliks and the shali group of rocks consisting in particular of dolomites, brick purple shale,

micaceous sandstones, red clay and mudstones (source: GSI, 50k geological map).

The hardness of those rocks is in preferred much less and further they had been subjected to deformation via

the thrust inside the vicinity, making them tremendously prone to landslides. Lineaments had been mapped

from the satellite tv for pc photograph. Deep incision of the tributaries shows that some of the lineaments will

be neo-tectonically active considering the fact that there are close to to the principle boundary thrust that

separated siwalik agencies from lesser himalayan rocks. In this way it ends up important to relieve the

heartbreaking contact with a detail comprehension of the physical procedure and adequate measure of

chronicled data evaluating the danger with both fleeting and spatial methodologies. As this Road is especially

vital from a transportation perspective and Landslide occasions along the streets totally remove the supply line

of different scattered slope stations and make it disconnected from the rest some portion of the nation.

The danger zonation regarding spatial likelihood along the correspondence communication route is less

adequate to manage the issue. Accordingly, it is important to consider the transient part of Landslide risk

keeping in mind the end goal to do a total quantitative appraisal of the wonder.

This specific research is an endeavor towards recognizing the potential and real Landslide inclined regions

and breaking down the likelihood of an event of Landslide .The modified methodology is an attempt in

formative the temporal vulnerability rate of landslide in a large scale with the exploitation of historical data,

field survey and satellite images.




Figure 1.1: Research Location of the Kotropi Landslide

[Source: Tripune India, National Remote Sensing Center]

Table 1.1: History of Landslides in Mandi

[Source: DISTRICT DISASTER MANAGEMENT PLAN MANDI]

Year Area

2000,2003,2004 There have been overwhelming precipitation nonstop rains all through

the Mandi area making across the board misfortune the streets,

structures, and extensions

July 26, 2006 Landslide covers four of family, Parwada(Mandi)

17.9.2005 Joginder Nagar, The aggregate harm to holding dividers, streets

structures, and bridges Rs 25 Laces.

2. Experimental Methodology- Some experiment work done on the soil which we collected on from

the landslide place. In the experiment main focus was on the engineering properties of the failed sample.

Before giving the conclusion first we have to find the engineering properties of the soil. Experiments

which perform on the soil are given below:

Sieve analysis of soil sample




Specific gravity of the soil sample

Stander Procter test on the given soil sample

Unconfined test

Direct shear test on the sample soil.

2.1 Sieve analysis of soil sample (IS:2720 part 4- 1985)

Sieve analysis is performing to know the type of soil. By this experiment we can explain that the soil

sample is well graded or poorly graded or the uniformly graded. Sieve analysis is important

experiment to find the engineering properties of the soil. This experiment should be performed as the

Indian standard codes.

Cumulative weight of soil retained of the each sieve should be calculated.

2.2 Specific gravity of the given soil sample

Indian Standard gives the definition of Specific gravity

” The ratio of the weight in air of a given volume of soil solids at a stated temperature to the weight in

air of an equal volume of the distilled water at that temperature”

According to the Indian standard specific gravity will be measure by the formula:

G= (A2-A1) ÷ [(A4-A1)-(A3-A2)]

A1 = Mass of gas jar and ground glass plate

A 2 = Mass of gas jar, plate and soil

A 3 =Mass of gas jar, plate, soil and water

A 4= Mass of gas jar, plate and water.

While doing the experiment it should be confirm that the room temperature should be 27 degree

Celsius. Correction should also applied by the formula of

G’ = KG

Where G’= Corrected specific gravity at 27 degree Celsius and

K= relative density of water

2.3 Stander Procter test on the given soil sample This method is used for the find the relation between the water content and dry density of the soil

sample using the light compaction on the soil sample. In which we take a rammer of 2.6kg falling from

the height of 310mm is used in this experiment. This test is more important for the finding the optimum

moisture content and dry density of the soil in which we used the IS 2720-PART 7-1980 for the

calculate purpose.

Calculation of the Bulk density can be calculated from the given formula.

Bulk density

𝛶𝑚 = 𝑀2 − 𝑀1

𝑉𝑚

M1=Mass of the mould and base plate in the (g)

M2=Maas of the base plate, mould and soil (g)

Vm=Volume of the mould (ml)

Dry density

𝛶𝑑 =100𝛶𝑎

100 + 𝑤

Where

w=Moisture content of the soil in percentage.

2.4 Unconfined test

Unconfined compression test is use to find out the compressive strength of the soil. Some time it hard

to find the correct type of soil to make embankment or earthen dam etc. the compressive load per unit

area mandatory to fail the specimen and then that is called as unconfined compressive strength of the

soil.




2.5 Direct Shear test

The shearing power of the soil the usage of the direct shear take a look at has been decided. The shear

strength of soil approach is its assets in opposition to sliding alongside inner planes inside itself. The

stableness of slope in an earth dam of hills and the inspiration of the structure constructed on one-of-a-

kind types of soil rely upon the shearing resistance supplied by means of the soil along the viable

slippage surface. Shear parameters are also used in computing the safe bearing ability of the inspiration

soils and the earth pressure in the back of maintaining walls.

Shear strength is determined as below

S=C+ϭtanΦ

Where

S = Shear strength of soil

C=Cohesion

The parameters c and ᶲ for a particular soil depend upon its degree of saturation, density and the

condition of laboratory testing.

3. Results and Discussion

3.1 Sieve Analysis

After sieve analysis of the sample we can say that sample has 10 percent of gravel, 69.212 percent of

sand and 20.788 percent of silt and clay.

Table 3.1.1: Soil classification according to Indian Standards

Table 3.1.2: Result of Sieve Analysis

Sieve Analysis Result

Serial

number

Sieve size

(mm)

Retainingweight of soil

(gram)

% of Retainingsoil

1 4.75 0 0

2 2.36 100 10

3 1 362 36.2

4 0.850 11.03 1.103

5 0.600 64 6.4

6 0.425 107.53 10.753

7 0.212 111.41 11.141

8 0.150 36.15 3.615

9 0.075 76 7.6

10 Pan 131.88 13.188

Graph 3.1: Graph between Sieve Size and Weight of soil sample

MIT CLASSIFICATION OF SOIL

Gravel 10

Sand 69.212

Silt and clay 20.788




3.2 Specific Gravity

It was observed from the experiment the soil sample have specific gravity is 2.677 it is means percentage

of Chlorite is more in the soil sample.

Table 3.2.1 : Result of Specific gravity test

Specific gravity

Sample Specific gravity

Soil 2.677

3.3 Standard Proctor Test

Standard proctor test helps to find the Dry density and OMC of the soil sample ,In this table we shows

the result of the percentage of water content and dry density and it was observed from the experiment the

OMC of the 16.3 further it used for the Direct shear test and UCS test.

Table 3.2.2: Table between percent of Water contains and Dry density

Standard proctor test result

Water contain in % Dry density

4.691 1.485

8.6 1.552

12.3 1.627

16.3 1.764

22.0 1.670

24.1 1.580

29.0 1.362

Graph 3.2.1: Graph between Water percentage and Dry density

0

100

362

11.03

107.53

64

111.41

36.15

76

131.88

0

50

100

150

200

250

300

350

400

4.75 2.36 1 0.85 0.425 0.6 0.212 0.15 0.075 Pan

We

igh

t o

f so

il sa

mp

le

Sieve Size

Sieve analysis




3.4 Direct Shear Test

Direct Shear test helps to find out the Shear strength, C and Φ of the given soil sample. It was observed

from the experiment the value of the C is 0 and Φ is 330 degree shown in graph 3.4.1.In this graph the

value of C is 0 it means we can say that the soil is Cohesion less also it was proved from the sieve analysis

this soil is Sandy soil. In table 1Shows the Shear Strength of the soil with different Shear Stress.

Graph 3.4.1 : Graph between the Normal Stress and Shear Stress

Table 3.4.1: Table of the Load Verse Shear Strength

Normal Stress (Kg/cm2) Shear Strength (Kg/cm2)

0.05 0.032

0.10 0.0649

0.15 0.0975

4. Conclusion

1.485

1.552

1.627

1.764

1.67

1.58

1.362

1.3

1.4

1.5

1.6

1.7

1.8

0 5 10 15 20 25 30 35

Dry

de

nsi

ty

water percentage

Standard Proctor Graph




In the sieve analysis, it has found that the sand is 69.212 % which means the sample soil was mostly

sandy due to which plastic limit is impossible to found. Maximum dry density found on 16.3 % of water.

In the direct shear test, Φ was 330, C=0 and the mean shear strength was 0.0648 kg/cm2. We can say by

the result that the soil have low shear strength which is the reason for the landslide.

Adequate and properly designed culverts should be provided to channelize the water coming from

upslope. Suitable vegetation should be planted on the slope to help slope stability by removal of water

and reducing surface soil erosion, as root grows across the failure planes it acts as root reinforcement to

slopes. The outcomes of this assessment will help in the further research aimed to think rainfall induced

landslide and their mitigation. Secondly relationship between landslides activity and rainfall can be

established for Himachal Pradesh region by studying other variation in the rainfall pattern.

5. References

1. Landslide incidence of 13th August 2017 at Kotropi on National Highway-154, Padhar Tehsil, Mandi

district, Himachal Pradesh.

2. Eko Setya Nugroho , Landslide incidence of 13thAugust 2017 at Kotropi on National Highway-154,

Padhar Tehsil, Mandi district, Himachal Pradesh, 2012

3. Sashikant Sahoo ,A Semi Quantitative Landslide Susceptibility Assessment Using Logistic Regression

Model & Rock Mass Classification Sysytem:Study in a part of UTTARAKHAND Himalaya ,India

4. Assessment of Kotropi Landslide, Mandi District, Himachal Pradesh (13th August ,2017) dated

17.8.2016 DSC/NDEM Map no :2017/02, NRSC/ISRO, Hyderabad

5. IS 2720 Method of test for Soils, Part 13, and Part 4and Part 3.

6. Kotropi Landslide, Mandi District ,Himachal Pradesh,

7. National Remote Sensing Center /ISRO, Hyderbad, Event id-4-LS-Himachal Pradesh, 15 August

2017.

8. Muhammad G.Barik, Landslide Susceptibility Mapping to Inform Land use Management Decisions in

Altered Climate, May 2010.

9. Surya Parkesh,Comprehensive Landslides Risk Management ,National Institute of Disaster

Management ,Ministry of Home affairs ,Govt. of India ,2012

10. Cruden,D.M.,Varnes,D.J.,1996,LandslideTypes and Processes, Report, Transportation Research

Board ,National Academy of Sciences ,247:36-75 ,July 15,1993.

11. Data of Land Slide in Himachal Pradesh Landslide vulnerability Zonation Atlas of India, Building

Material and Technology Promotion Council

12. History of Landslides in Mandi ,District ,Disaster Management Plan Mandi


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