Geotechnical and Geological Studies of Rockfall and Landslides along Mumbai Pune Expressway

IJIRST –International Journal for Innovative Research in Science & Technology| Volume 3 | Issue 12 | May 2017 ISSN (online): 2349-6010

Graph Database: A Complete GDBMS Survey Anubhav Boshat Student Department of Civil Engineering Bharati Vidyapeeth Deemed University College of Engineering Pune (411043)

Manish Malik Student Department of Civil Engineering Bharati Vidyapeeth Deemed University College of Engineering Pune (411043)

Raghav Agarwal Student Department of Civil Engineering Bharati Vidyapeeth Deemed University College of Engineering Pune (411043)

Prof. R.S Patil Assistant Professor Department of Civil Engineering Bharati Vidyapeeth Deemed University College of Engineering Pune (411043)

Prof. N.R Patil Assistant Professor Department of Civil Engineering Bharati Vidyapeeth Deemed University College of Engineering Pune (411043)

Abstract Mumbai-Pune is the India’s first expressway, which passes from the mountainous regions of the Deccan Trap. It has suffered from a large number of rockfall and landslides during 2003-2004. A very large number of accidents have occurred on the Mumbai-Pune expressway. On the basis of frequency and magnitude of the recorded incidences of rockfall on the expressway. It have been taken in need of investigations and mitigation. Based on the geological and geotechnical investigations, various causes for rockfall and location at this location have been established.

Keywords: Expressway, Landslides, Rockfall, Deccan Traps _______________________________________________________________________________________________________ I.

INTRODUCTION

Mumbai is the commercial capital of India. Its growing rate is significantly high in size and population. Pune is the cultural capital of Maharashtra. It is also growing into a major industrial and commercial center. Hence, the importance of the MumbaiPune road has increased enormously in the last 8–10 years. According to one estimate, 450 people are killed due to accidental events on the existing Mumbai-Pune National Highway each year.

For these reasons, the government deemed it necessary to construct a new, separate expressway. The expressway is 95 km in length. It was inaugurated on March 1, 2002.The expressway has reduced the distance between Mumbai and Pune. By routing through this expressway there is reduction in travel time by 2 hours. The expressway has a very high traffic rate that is 1,00,000 vehicles passes from the expressway per day. During 2003 and 2004, the expressway experienced a very large amount of rockfalls and landslides. Investigations have been carried out from various aspects like geologically and geotechnically.

II. OBJECTIVE  

To carry out various Geotechnical tests on the soils of various areas of Deccan traps on Mumbai – Pune expressway and finding out the nature of soils present there.

To find out the main reason for rockfall and landslides and determine the geotechnical and geological reasons responsible for it.

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Graph Database: A Complete GDBMS Survey (IJIRST/ Volume 3 / Issue 12/ 035)

III. ROCKFALLS AND LANDSLIDES A rockfall or rock-fall refers to quantities of rock falling from a very high cliff face. If the roof or walls of quarry mine gets collapsed it can also be termed as rockfall. A rockfall is a downward movement of fragments of rock (a block) that are falling along the slope under the influence of gravitational force. In other words "rockfall is the naturally downward movement of a detached block or series of blocks involving free falling, bouncing, rolling, and sliding".

A landslide is a rapid, gravity caused events that results in falling of rocks, boulders soil masses. Basically landslides is a disaster in which the whole land area along the slope collapses and slide down. Landslides can also be known as slope failure.

Landslides that can occur in underwater are known as submarine landslide.

Gravitational force is the major driving element apart from that there are various other causes which are also responsible for landslides to occur like overloading slopes, removal of vegetation, seepage of water, vibrations caused by earthquake etc.

Geotechnical Investigations: Geotechnical investigations include the evaluation of type of soil near the Mumbai-Pune expressway. This includes the following tests that were carried in the laboratory. There are 4 samples that were collected from the various areas of expressway.

Followings test were conducted on these samples:  Moisture Content  Specific Gravity  Sieve Analysis  Liquid Limit  Plastic Limit

Sample A B C D

Table – 1 Picture of soil samples from right to left (A,B,C,D) Location Moisture Content (%) Khopoli 3.96 Near Kamshet Tunnel 2.48 Khandala ( West to Monkey Point) 3.07 Kusgaon along Pune- Mumbai side 1.76

Specific Gravity 3.22 1.65 2.17 2.34

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Graph Database: A Complete GDBMS Survey (IJIRST/ Volume 3 / Issue 12/ 035)

Moisture Content: -

From the following results it is observed that the moisture content present in the soil is quite less that depicts the low absorbance of water by the soil.

Specific Gravity: Samples A B C D

Soil Type Contain heavy substances i.e lateritic soil (G > 3) Porous particles & Organic matter are present (G < 2) Organic & Clayey ( G between 2-3) Organic & Clayey ( G between 2-3)

Sieve Analysis: Samples

Location

A B C D

Khopoli Near Kamshet Tunnel Khandala (West to Monkey Point) Kusgaon near Pune-Mumbai Expressway

Gradation of soil Cc CU 0.9 12 2.2 9 1.1 8.2 1 6.1

Type Well graded sandy soil Well graded sandy soil Well graded sandy soil Well graded sandy soil

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Graph Database: A Complete GDBMS Survey (IJIRST/ Volume 3 / Issue 12/ 035)

Liquid Limit, Plastic Limit and Plasticity Index Samples A B C D

Liquid Limit 12.55% 13.4% 14.9% 7.8%

Plastic Limit 6.66% 8.33% 7.14% 7.1%

Plasticity Index 6.19% 5.07% 7.78% 0.7%

Type Low plastic Low Plastic Medium Plastic Non Plastic

Water Content (%)

SAMPLE - A 14 13.8 13.6 13.4 13.2 13 12.8 12.6 12.4

Series1

1

5

25

125

Number of Blows

Water Content (%)

SAMPLE-B 14.4 14.2 14 13.8 13.6 13.4 13.2 13 12.8 12.6 12.4

Series1

1

5

25

125

Number of Blows

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SAMPLE - C Water Content (%)

16 15.5 15 14.5 Series1

14 13.5 13 1

5

25

125

Number of blows

SAMPLE - D 10 9

Water Content (%)

8 7 6 5 Series1

4

3 2 1

0 1

5

25

125

Number of Blows

Geological Investigations: The area is made up of basaltic rocks and basaltic rocks are classified into 4 types.

1) Compact Basalts 2) Amygdaloidal Basalts 3) Tachylitic Basalts 4) Volcanic Breccias Compact and Amygdaloidal basalts are separated by a thin layer of disintegrated material which is formed by weathering of basaltic rocks. Sometimes these two are separated by tachylitic basalt rocks which on exposure to atmosphere disintegrate forming boles which disturbs the middle layer of compact and amygdaloidal basalt causing rockfalls.

As in the following picture there is a layer of red tachylitic basalt which is in between the two basaltic rocks and the tachylitic basalt is disintegrating and falling down.

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Graph Database: A Complete GDBMS Survey (IJIRST/ Volume 3 / Issue 12/ 035)

Also there is seepage of water from the joints and fractures which are slowly falling down making the slope susceptible to fail.

IV. CONCLUSIONS 1) Soil samples are of low to medium plastic nature due to which they do not have sufficient cohesive strength to have a stable slope which results in landslides.

2) The soil present is well graded but they are sand and some amount of silt present in it.

3) The soil samples are lateritic soil that are formed because of the humid climatic conditions. Apart from that some soil had organic matter present in them and other soil was porous in nature which results in seepage of water.

4) The seepage of water through joints and fractures made the slope weak which results in falling of rocks.

5) The joints were inclined instead of being horizontal.

6) The soil present does not have enough cohesive strength to prevent the slipping of rock masses along the inclined joints which are dipping towards the expressway.

7) The rocks are detaching from the joints present in them.

REFERENCES [1] [2] [3] [4] [5] [6]

M. K. Ansari, M. Ahmad, T. N. Singh “Rockfall Risk Assessment along Mumbai-Pune Expressway, Maharashtra, India”.

Soil Mechanics and Foundation Engineering by B.C Punmia IS: 2720 Part 2- 1969 IS: 2720 Part 3 1980 IS: 2720 (Part 4) – 1985 IS: 2720 (Part 5) – 1985

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