indian railways construction bulletin

FROM THE DESK OF THE EXECUTIVE EDITOR

Dear Readers,

Every year,“15th September ” is being celebrated as the “Engineer’s day” to commemoratethe birth day of Bharat Ratna ,Sir Mokshgundam Visvesvaraya (1860-1965), who is also called the“Wizard of Engineering.” He not only took keen interest in Engineering but also applied his talentto many allied matters connected with the development of the nation. Let all Railway engineers beinspired by this great engineer and make Indian Railway the number one Railway in the world.

The September issue of “ Construction Bulletin” features two articles. The first article isabout Green buildings. Green building refers to building which is energy efficient andenvironmental friendly.

The second article “ Execution of deep cutting with special reference to stability of slope” inone of the gauge conversion projects, describes a simple in-situ test conducted at site to deter-mine the stability of slope in deep cutting

The best way to disseminate knowledge is through publication of articles on the specialisedworks being carried out by you. The readers are requested to actively participate by sendingarticles on various issues related to construction, which you feel important to be shared with othersthrought this forum. The articles may be sent on a CD or throught e-mail at [email protected] . Thisbulletin is also available on the website at www.iricen.gov.in

With best wishes

- Executive Editor

gå[mXH$ _§S>bEDITORIAL BOARD

lr oed Hw$_ma oZX{eH$ / Bnag{Z AÜ`jShri Shiv Kumar Director /IRICEN Chairman

lr EZ.gr. emaXm dnað> àmÜ`m[H$ / Bnag{Z gXñ`Shri N.C. Sharda Sr. Professor / IRICEN Member

lr amO{e Hw$_ma àmÜ`m[H$ / Bnag{Z gXñ`Shri Rajesh Kumar Professor / IRICEN Member

lr KZ>>e`m_ ]§gb àmÜ`m[H$ / Bnag{Z gXñ`Shri Ghanshyam Bansal Professor / IRICEN Member

lr AO` Jm{`b dnað àmÜ`m[H$ / Bnag{Z H$m`©H$mar g§[mXH$Shri Ajay Goyal Sr. Professor / IRICEN Executive Editor

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INDIAN RAILWAYS CONSTRUCTION BULLETIN

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VH$ZrH$s [{[g© / TECHNICAL PAPERS

1. Green Building “The Habital for Future”by A. K. Rai, Professor, IRICEN, Pune

2. Execution of Deep cutting with special Reference to Stability of slopeby Manjul Mathur, Dy Chief Engineer, South Central Railway, Secunderabad

& V. S. Khobare, SSE / Works / Kinwat

VH$ZrH$s [{[g© H{$ b{IH$m| Ûmam ì`·V oH$E JE odMma AoZdm ©̀ ê$[ g{ Bnag{Z H{$ odMma Zhr h¢$&The views expressed by the authors of technical papers are not necessarily the views ofIRICEN.

Ûmam àH$moeVPublished by

oZX{eH$The Director

^maVr` a{b ogodb B§oOoZ`ar g§ñWmZIndian RailwaysInstitute of Civil Engineering

[wU{{ - 411 001.Pune - 411 001.

I§S> 16, H«$_m§H$ 2

Volume 16, Number 2

flracj 2006

September 2006

C O N T E N T Sodf` dñVw

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Green Buildings “ The Habitat for Future”

1.0 Introduction

‘Green Building’ is a concept which is rapidly gaining acceptance in the country.In simple terms it refers to a building which is energy efficient and environment friendlyin terms of minimal disturbance to environment during construction and service. However, when we use the term “Green Building” we are not talking of the building only. Ratherthe term encompasses the planning, construction processes and service performanceaspects. Green buildings result from integrated design and construction processes whichreduce the negative impact of building on the environment and the occupants. TodayGreen Buildings are considered to be important component of any model forsustainable urban development.

Most of the construction material are obtained from the nature and subsequentlyprocessed. The manufacture of building materials and the construction processesdisturb the environment and consume energy. The disturbance to environment includesdepletion of ground cover, cutting of trees and soil erosion due to change in land useand excavation.

Buildings are the third largest consumers of energy after industry andagriculture. The actual consumption varies from building to building depending on thenature of building in terms of use of the building, air conditioning, and other facilities.However in all categories of buildings the consumption of electricity is going toincrease further in coming years.

Several construction materials emit polluting gases for a long period after theconstruction. These include paints, varnishes and vinyls. These toxic constructionmaterials cause harmful effect on health of inhabitants.

These issues can be addressed by adopting green features in buildingconstruction. The concept has been popular in USA and several other countries. Thesecountries have rating systems to assess ‘green’ character of buildings. At the sametime in these countries many local bodies have set norms for green features to beincorporated in buildings.

2.0 Objectives of Green Buildings

The fundamental objectives of green buildings are to conserve natural resourcesand increase energy efficiency. Conservation of resources also includes reducing damageto ecology due to construction activity. Increasing energy efficiency involves harnessingnature to minimize need for electricity for operation and maintenance of the building.Another important objective of Green Buildings is to improve indoor air quality.

byA. K. Rai *

* Professor, IRICEN, Pune

^maVr` a{b oZ_m©U H$m`© [oÌH$m Indian Railways Construction Bulletin 1I§S> 16, H«$_m§H$ 2, ogV§§]a 2006 Vol. 16, No 2, September 2006

Construction of buildings and structures is a major activity which contributes tothe economy of the country. Building construction activity causes damage to ecologythrough land use disturbance, energy intensive materials and processes, generation ofwaste and increased air and water pollution. The green buildings aim at minimisingthis damage by adopting appropriate designs and construction procedures.

Buildings consume about 31% of global energy. This figure is likely to go up to38% by 2050. In India, the present consumption of energy in buildings is about 25% oftotal energy consumption. The average annual energy consumption in a commercialair-conditioned building in India is 300 kilowatt hour per square meter. By adoptinggreen building practices this consumption level can be reduced to half. Though therequirement of power for hybrid and non air-conditioned buildings is less, but there isgreat scope for reduction in power requirement for such buildings also. Such a savingwill not only reduce the power bills but also mitigate the power shortage in the countryto a great extent. One unit of power saved is equal to two units of power produced.Therefore, going in for green buildings makes a lot of sense for an energy deficientcountry like India.

Construction materials like paints, varnishes, adhesives and vinyles emitpolluting gases such as nitrous oxide and carbon dioxide for considerable time afterthe construction . It has been estimated by U. S. Environmental Protection Agencythat air in new homes can be ten times more polluted than outside air. The indoor airquality in new houses is an area of concern in western countries. Here again, thegreen building aims at avoiding or minimising use of toxic construction material.

3.0 Broad Criteria

There are a number of features based on which a building can be evaluated on‘green’ scale. These features cover all the three stages in the life of building namely,planning, construction and service. However the features can be clubbed underfollowing broad criteria :

1) Sustainable site planning2) Social responsibility3) Appropriate landscape design4) Eco-friendly construction materials and practices5) Water management6) Energy efficiency and use of non-conventional energy sources7) Health and well-being


4.0 Benefits from Green Buildings

A number of benefits are expected to accrue from green buildings to the

society as well as to the individual. Some such benefits from green buildings, ascompared to conventional buildings are :

1) Less ‘damage’ to environment by design; choice of material and process; andreduced construction waste

2) Reduced energy consumption through energy efficiency and use of renewableenergy and hence, reduced electricity bills

3) Mitigation of water scarcity through efficient water management4) Efficient use of resources during and recycling

5) Better indoor air quality by use of non-toxic materials etc.

5.0 Cost of going ‘Green’

The green buildings cost more than the conventional buildings, the difference ofcost being dependent on green features being incorporated in the design andconstruction. A green building may cost 20% to 50% more but annual energy costswould go down by 30% to 65%. However, over a certain period, depending on theenergy requirement of the building, the additional expenditure will be compensated bythe reduction in annual energy bill. This pay back period would vary from building tobuilding. However, over the life cycle the green buildings would turn out to be more

economical as compared to conventional buildings.

6.0 Strategies for Green Buildings

A large pool of green features and techniques are available for adoption indesign and construction of buildings. Appropriate ones have to be selected dependingon function and type of the building, climatic conditions etc. Some such feature whichaim at fulfilling the criteria for green buildings are as follows:

6.1 Sustainable site development

The site planning should ensure minimal damage to site and surroundings.a) Land should be disturbed only to the extent it is unavoidable.b) Preserve land in the surrounding area.c) Avoid disturbance to water courses.

d) Minimise cutting of trees and undertake compensatory plantation.


e) Replant the grown up trees.

f) Preserve the excavated top soil and use it in landscaping.

g) Adopt erosion control measures to prevent erosion of exposed soil.

6.2 Social Responsibility

a) Ensure safety provisions at construction site.

b) Provide sanitary facilities for workers.

c) Raise screens to minimize air pollution in the area around the construction site.

6.3 Appropriate Landscape Design

a) Landscape to be designed to avoid ‘heat island effect’.

b) Hard surface to be minimised. If hard surface is provided it should be porous

and shaded by vegetation to the extent feasible.

c) Species of plants requiring less water for survival and growth to be preferred.

d) Native species of plants to be preferred.

6.4 Construction Material and Practices

a) The design of the building should be resource efficient. Requirement of material

should be less than that for a conventional building.

b) Low energy intensive materials to be preferred. These include regionally

available material and material which require less energy during manufacturing e.g.

local stones, composite woods, form wood etc.

c) Materials derived from waste of other industrial processes such as fly ash and

other eco-friendly material to be used in construction.

d) Utilisation of construction waste at the same site or at other construction sites.

6.5 Water Management

It consists of reduction in water demand, avoiding wastage of water and

conservation strategies like rain water harvesting and waste water utilization.

a) Some measures which can go a long way in reducing water demand for land

scape has already been discussed under ‘Appropriate landscape design’. These

include planting of native species (shrubs / trees) and other species requiring

less water.

b) Use of sprinklers for lawns and drip irrigation for shrubs and trees.


c) Waste water treatment and use of treated water for irrigation of landscape.

d) Rain water harvesting and use of stored water for irrigation.

e) Use of low discharge fixtures such as double discharge flush in the building to

bring down water demand.

f) Intelligent feature such as urinals having sensors in public places and mass use

locations.

6.6 Energy Efficiency

Energy efficiency is one benefit from green buildings which appeals to all. Thegreen buildings incorporate energy efficiency primarily through reduced requirement ofpower for lighting and air conditioning.

Several traditional Indian designs provide for efficient natural lighting,ventilation and thermal insulation. For example the Indian circular courtyard designenhances air and light. The jali works used in several medieval building including TajMahal cools the air.

There are a number of features which contribute to energy efficiency ofbuildings.

a) Architectural design should aim at creating optimum thermal and visualconditions in the building thus reducing the need for artificial lighting, forcedventilation and air-conditioning.

b) Bio-climatic architectural principles for optimum use of nature for lighting andspace conditioning should be applied. These include orientation, positioning,coating and shading of windows, selection of suitable materials for wall, roofand windows, and thermal insulation of roof and walls. If the building isdesigned taking the bio-climatic principles into consideration, the energy loadcan be easily reduced by about 20%.

c) There are several solar passive features such as courtyard pattern, solarchimney, wind tower and earth tunnel which can be incorporated. With the useof courtyard pattern and solar chimney the hot air is made to move upwards sothat cooler air from vegetated areas can move in. The wind tower and earthtunnel facilitate cooling of air before it is supplied to the air-conditioning system.

d) Use of efficient air conditioning and water cooling systems having intelligent features.

e) Use of efficient light fittings such as CFLs, T-5 lamps etc. and use of sensors(illumination meters ) to avoid wastage.

f) Another important component of Green Building concept is harnessingnon-conventional sources of energy such as solar energy for heating andelectricity generation or gasifier system to utilize bio-waste. Solar water heaters


and solar photo-voltaic cells are obvious options for harnessing solar energy.Similarly bio-gas plants are to be used to generate energy from bio-waste.

6.7 Health and Well Being

a) Indoor air quality can be improved by using non-toxic (low VOC) paints and

adhesives.

b) CFC free HVAC and refrigeration system

c) Halogen-free fire suppression systems

7.0 The Indian Scene

In recent years some major buildings constructed in the country have adopted

green features. These includes the CII-Sohrabji Godrej Green Business Centre,

Hyderabad, TERI’s Retreat Building, Gul Pahari, Gurgaon, Laboratory Building IIT

Kanpur , Transport Corporation of India Ltd, Gurgaon and National Media Centre

Cooperative Housing Scheme, Gurgaon. Two such buildings are being discussed in

following paragraphs.

7.1 CII-Sohrabji Godrej Green Business Centre, Hyderabad :

It is a matter of great pride for Indians that this Indian building was adjudgedas world’s ‘Greenest’ building in the year 2003. In that year the CII – SohrabjiGodrej Green Buisiness Centre in Hyderabad, a 20,000 sq. feet building designed byVadodara based architect Karan Grover was awarded ‘Version 2 Platinum’ rating byUnited States Green Building Council (USGBC), Pittsburg. The Council recognisesstructures for environment friendly materials and techniques; and energy efficientarchitecture.

Fig.1 CII-Sohrabji Godrej Green Business Centre, Hyderabad


The ‘Version 2 Platinum’ was the highest rating achieved by any building, under

the Leadership in Energy and Environment Design (LEED) Systems for rating for

environmentally conscious buildings. The Hyderabad building was credited with 57 of

62 parameters it had competed in. Three buildings in U. S. A. had won the next lower

rating i.e. ‘Version 1 platinum’ till then.

The green features of The CII – Sohrabji Godrej Green Business Centre

building include the following :

(1) Ninety percent of the building doesn’t require any artificial lighting during the

day.(Fig.2)

(2) Two forty feet wind towers and screen walls provide air pre-cooled by 100C to

the air conditioning systems

(3) Photovoltaic panels are built in to generate solar energy which fulfill 20% of

building’s energy requirement.(Fig.3)

4) Thermal insulation of walls, glazings and roof.

5) Electric fixtures have been automated to save power

6) Material used were recycled and eco-friendly broken mosaic tiles, steel, wood,

glass, fly ash brick, locally available store and non-toxic paints.

7) Water is treated on-site and used for gardens

8) Rain water Harvesting

Fig.2 : Adequate Natural Lighting Fig.3 : Solar Energy being harnessed


7.2 Retreat Building of TERI at Gurgaon

Apart from adopting bio-climatic principles in the design, two solar passive

features namely earth tunnel and solar chimney have been incorporated in the

building design. The building has Solar water heating system and Photo-voltaic cells

for harnessing solar energy and gasifier system for using bio-waste. Landscaping has

been done to suit the climate. There is also a waste water treatment system and treated

water is used for irrigation.

8.0 Rating of Green Buildings

In USA and some other developed countries there are several voluntary Rating

Systems for Green Buildings. The most widely known system is the LEED (Leadership

in Energy and Environmental Design ) system administered by Green Building

Council, Pittsburg, USA. However most of these systems are applicable to

air-conditioned buildings only. In India TERI (The Energy and Resources Institute ) has

prepared a voluntary rating system for green building certification of buildings in India.

This system, known as TERI-GRIHA (Green Rating for Integrated Habitat

Assessment) is applicable to both air-conditioned and non air-conditioned

buildings. The Rating System is being administered by TERIBCSD ( TERI

Business Council for Sustainable Development).

Under this rating system, the performance of the building is to be assesses on

the basis of 32 criteria covering Site Planning, Building Planning and Construction, and

Building Operation and Maintenance. Some of these criteria are mandatory. Points can

be earned against each of the criteria and buildings earning 50 or more points out of

100, are entitled for certification and star rating.

9.0 Conclusion

The green buildings involve additional initial costs but over the life cycle these

buildings turn out to be more economical. Besides, from the environmental and social

consideration, it is desirable to go for green buildings. It is expected that the

recognition of CII – GBC building as the ‘greenest’ building in the world and launching

of TERI-GRIHA would act as a stimulus and increase green consciousness in India.

The new IRICEN building at Koregaon Park, Pune would perhaps be the first green

building on Indian Railways.


EXECUTION OF DEEP CUTTING WITH SPECIAL REFERENCETO STABILITY OF SLOPE

by

Manjul Mathur * and V. S. Khobare @

1. INTRODUCTION:

Widening of deep cuttings in Gauge Conversion projects has been achallenging task before the Engineers. Once the face of cutting that had been stable fornumber of years gets disturbed, it unfolds a series of problems. Therefore before sucha task is undertaken, a careful study of engineering properties of existing soil shouldbe done to determine the stable slope and a careful execution should then follow. Thebasis of design of slope had been traditionally through collection of undisturbed/disturbed samples and performing appropriate test in laboratory under controlledconditions. However, if the properties of soil can be determined in-situ or as close totheir natural state as possible the results will be much more reliable. This paperdescribes a simple in-situ test conducted at site to determine the stable slope.

2. TOPOGRAPHY

The section Ambari- Kosai of Adilabad- Mudkhed Gauge Conversion projecthad a continuous graded stretch from Km. 130- 133, with the gradient during the MGdays being 1 in 67. During the Gauge Conversion,a study was made to flatten thegradient, however because of deep cutting in this length, easing of gradient beyond 1in 80 proved to highly un-economical. Besides the above it was very difficult toacquire the land, as the section passed through the reserved forest. The existingheight of cutting had been 20 m. Flattening of gradient even to the extent of 1 in 80required the cutting to be lowered by 5 m. It was therefore decided to provide agradient of 1 in 80 (compensated) duly shifting the alignment by 5.1 m in order toavoid or create minimum disturbance to at least one face of cutting. (Fig. 1)

130400 130800 131200 131600 132000 132400 132800 133200 133600 134000 134400360

364

368

372

376

380

384

388

392

396

400

404

408

412

416

420

424

428

CHAINAGES

RE

DU

CE

D L

EVE

LS

EXTG GROUND LEVELSEXTG MG LEVELSPROP BG LEVELS

HARDINTACT ROCK400 M

HIGHLY FRACTUREDROCK 800 M

HIGHLY FRACTUREDROCK 900 M

25 M

5 m

Fig.1 Cross sectional details of Cutting* DY.CE/C/TP/ SC RAILWAY@ SSE/Works/KINWAT


3. Goelogy of Site

The site was a hilly terrain, an extension of Sahyadri, composed of volcanicrock, the Deccan trap. The central 400 m portion of cutting comprised of hard intactrock. Though it had weathered to some extent, the degree of weathering was notuniform. While in the center portion hard intact rock was seen, towards the endweathered / fragmented rock pieces could also be seen. Considerable difficulty wasexperienced in blasting and breaking the rock for widening. The blasted rock piecesmet the specifications of Railway Ballast in terms of attrition value, abrasion value andwater absorption and they were in fact used for ballasting a substantial length ofcutting. Near the mouth of cutting, the soil was highly fragmented and was easilyremoved with the poclains. (Fig.2)

In view of soil with rock fragments of size 50 mm and above, the matter was referred toDr. M. R. Madhav, Retd. Professor, IIT, Kanpur for suggesting the stable slope. Underhis guidance an In-situ tilt test was conducted at site.

Fig.2 View of Cutting, its face and material.


4. In-Situ Tests

Several in situ tests like standard penetration test, cone penetration test, vane shear

tests are being conducted to determine the engineering properties of soils. Jain and Gupta

(1974) report, uses a 1.2 m square direct shear box for in situ direct shear test. The maximum

size of particles was 200 mm. Prakash and Ranjan (1976) modified the standard test set to

carry out simultaneously two in situ direct shear tests on boulder deposits. The specimen size

was 1.5 m square. Cancelli et al (2001) and Wasti and Ozduzgun (2001) report the

development of Inclined Plane test for determination of interface shear resistance of

geo-synthetics with soil and also between different layers of geo-synthetics. The size of

specimen was 400 mm X 335 mm. However, it is rather impossible to carry out test on the

slope itself. Therefore, a large shear box 1.0 m square was used at site to determine the shear-

ing resistance of rock fill. (Fig 3)

The equipment consists of two boxes 1 mx1mx0.25m made up of MS sheets. The upper box

was opened at both top and bottom while the lower box was open at top and closed with a MS

plate at the bottom. Both the boxes had small pipes welded on all four sides. The boxes were

kept one over the other and filled with rock fill. During filling, the boxes were held together with

the rods smaller in diameter than the inside diameter of pipes to prevent the relative motion.

The top edge of the bottom box and bottom edge of top box were ground to make them smooth

and minimize the friction. (Fig. 4)

Fig.3 Test equipment

34°THETA

H

L


Ø

The boxes were kept on ground and filled with the rock fill/ soil in 5- 6 layers each time

compacting the layer with the rods to bring the rock fill/ soil mass as close to the naturally

compacted state as possible. After the boxes were completely filled up the rods holding them

together were removed and the boxes were gradually lifted through the cable attached at one

end of bottom plate with a poclain. The height (H) at which the top box starts sliding down, with

respect to bottom box, was measured. The angle at which the shearing/ slipping takes place

can then be determined from sin ø = H/L where L is the distance from the point about which

lifting took place.

The test was repeated with soil/ rock fill in saturated condition to replicate the effect during

monsoon. The test was finally conducted with the empty boxes to determine the friction

between the edges of the boxes and correction was applied to the measured angle of shearing

resistance. (Fig. 5)

Fig.4 Test with dry rock fill

Fig.5 Test with saturated rockfill


The results obtained are as shown in the table below:

S.No.

Location ofsample

Max. Heightat Tilt (mm)

Angle of Tilt(Degrees)

Condition

Angle ofShearing

resistance(Degrees)

1

2

3

4

5

6

7

Ch. 132/225, TP side,

3 m above

Box Alone

Ch. 132/300, TP side,2 m above

Ch. 131/450 t0 131/550,NTP side, 4 m above

Ch. 131/450 to 131/550,NTP side, 4 m above

Ch. 131/650 to 131/850,TP side,10 to12 m above

Ch. 131/650 to 131/850,TP side,10 to12 m above

Dry

Dry

Dry

Saturated

Saturated

Saturated

- ----

1411

1218

1398

1036

1420

1350

377

69.6

54.0

68.3

43.5

70.65

63.8

14.5

55.1

39.5

53.8

29.0

56.15

49.3

—-

The angle of shearing resistance was obtained by subtracting the friction angle of box alone

from rest of the results. The net shear resistance of the rock fill was estimated to be 54 to 56

degrees in dry condition and 39.5 to 49.3 degrees in wet condition. Sample No.3 gave a low

value of the order of 29 degrees. Such a value is inadmissible for granular material. It is

possible that the sample was not compacted properly. Therefore the safe slope recommended

for the cutting was 1:1.

5.0 Design of Section of Cutting:

AREMA Manual of Railway Engineering stipulates the following cross section for the cutting

as shown in Fig. 5.

A B CBC

Fig.5 Cross section of cutting^maVr` a{b oZ_m©U H$m`© [oÌH$m Indian Railways Construction Bulletin 13I§S> 16, H«$_m§H$ 2, ogV§§]a 2006 Vol. 16, No 2, September 2006

S.No.

1.

2.

3.

The purpose of different segments is as follows:

Segment

A- Roadbed

B- DrainageDitch

C- CatchmentDitch(Optional)

Purpose

To provide base forsupporting ballast,sleepers and rails.

To carry run-off fromwatershed served,seepage entering cuttingand for service road

To contain materialwhich may fall fromfaces of cutting andfor service andmaintenance access

Whereprovided

Throughoutcutting

Throughoutcutting

Withinbroken orrapidlyweakeningrock cuts

Width and Profile

Standard width

Standard width with profilesteeper than track in longlevel cuttings

Of variable depths dependingon slope and height of cutface, size and rate of fall offragments and desirablefrequency of ditch cleaning.Primary consideration is toset the position of toe at apoint, which will not allowfragments to bounce intotrack area.

The important feature of the above profile is the catchment ditch, which will prevent any rock

fragment or boulder accidentaly falling from the top/ face of cutting, to come on to the track.

Taking cue from the above, it was decided to provide a 1500 mm wide drain cum catchment

ditch in the cutting, to provide drainage and also to prevent the rock fragments/ boulders to fall

on to track. As an additional precaution it was decided to provide rail and tie bar fencing on the

wall of drain adjacent to track. The height of this fencing was decided from the consideration; in

case it overturns due to falling of boulder, it should not infringe the track. A 1.5 to 3 m berm was

provided at half the height of cutting to intercept and reduce the velocity of falling rock

fragment. With the above considerations the following cross section was provided

as shown in Fig. 6PROPOSED DESIGN OF SLOPE

CC 1:2:4, 150 THICK

DRAIN CUM CATCHMENT DITCH

RAIL AND TIE BAR GRILL

CENTRE LINE OF TRACK

BERM AT MID HEIGHT

TOP OF CUTTING

2000

H/2

H/2

3125

61253650

1500

Fig.6 The slope design


6.0 Drainage :

A system of catch water drains was laid on the top of cutting draining the water to

natural water courses in Br. Nos.162 and Br. No. 163 on the either side of cutting. Care was

taken to provide the masonry walls at the locations where such drain was running very near to

the face of cutting to prevent the cutting material to become loose during monsoon and fall.

The cutting executed with the above profile has seen one monsoon season and no untoward

incident has been reported so far.

7.0 Conculsion :

Geotechnical Engineering is a science but its practice is an art. The in-situ test de-

scribed in the above paper is a simple test, which can be used for determining stable slope for

predominantly cohesionless soils with rock fragments/ soils with mild cohesion. The

maximum size of rock fragment can be as high as 125 to 150 mm with the box size of 1.0 m x

1.0 m. Safe slopes are governed by the characteristics of soil/ rock fill. Even in the same face

of cutting the stable slope angle will vary for sound rock, weathered rock and soil overburden.

Blasting tends to open up the cracks near the face of cutting allowing increased rate

of weathering, infiltration of water and consequent deterioration of face of the slope. Hence

despite taking all necessary precaution during widening, the widened face is likely to pave

way for rock falls in subsequent years. Therefore the provision of catchment ditch as

suggested in AREMA Manual is a good measure to prevent the rock fragments to come on

the track.


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