Proceedings of Indian Geotechnical Conference

December 15-17, 2011, Kochi (Paper No. Q-087)

GRAVILOFT RETAINING WALL: A CASE STUDY

R. J. Balwan, HOD, Govt. Polytechnic, Kolhapur, rajay64@gmail.com

Ajitkumar Kumbhar, Manager, C.E.C.M., M V M Ltd, Pune, kumbhar.ajitkumar@mahindra.com

ABSTRACT: Earth retaining structures cost is major cost in any infrastructural developmental project. Saving in earth

retaining structure influences the project cost. The use of gravity wall coupled with loft gives excellent combination,

resulting into about 40% cost saving. This has further advantages as no new material required, reduced foundation width,

uniform foundation pressure, no skilled labour required, speedy construction, material saving, etc. An attempt has been

made to work out the cost of construction of “Graviloft wall” and “RCC Cantilever and Gravity wall”. The comparison

clearly indicates a considerable reduction in the cost of construction.

INTRODUCTION

‘Retaining Structure’ is an indispensable feature of any

civil construction projects. Traditionally, Gravity Retaining

wall, Cantilever Retaining wall, Counterfort Retaining wall,

Buttress Retaining wall and Reinforced Earth walls are

adopted to retain soil at a slope steeper than that it would

naturally assume. It is noticed that the cost of earth

retaining structure is major one and therefore any saving in

earth retaining structure influences the project cost.

GRAVILOFT TECHNOLOGY Gravity retaining wall have limitations due to their bulky

section and higher cost. RCC cantilever retaining wall also

not cost effective for more height. The Graviloft technology

is essentially a marriage of Gravity Wall and R.C.C. wall

effected by the provision of a loft. In this concept the good

points of the gravity walls and R.C.C. walls are brought

together so as to save the resources. In this innovation, time

tested materials are used and the retaining wall which is

essentially gravity structure provided with reinforced loft,

which is built into it. The placement, geometric

configuration and the design of the loft is through

optimization.

CASE STUDY The site under consideration is Mahindra Vehicle

Manufacturers Ltd., Chakan Industrial Area, Pune. This

type of wall is extensively used at different locations within

the site area. For the present study a wall of 6.0m height is

considered for cost comparison. The cost worked out for

Cantilever wall section, Gravity wall section and Graviloft

wall section.

Cantilever R.C.C. Wall The total height of wall is 6.0m and base width of 4.2m.

The section is shown in Fig.1. The cost worked out per

running meter length of wall in rupees as :

Item Qty. Rate Amount

Excavation 28.8 m3 659 18979.2

PCC 0.44 m3 4761 2094.84

RCC 4.68 m3 5615 26278.2

Reinforcement 281 Kg 48.39 13598.71

Total = 60950.95

Gravity Wall The total height of wall is 6.0m and base width of 4.1m.

The section is shown in Fig.2. The cost worked out per

running meter length of PCC wall in rupees as :

Item Qty. Rate Amount

Excavation 28.2 m3 659 18583.8

PCC 0.41 m3 4761 1952

Plum concret 10.85 m3 3485 37812.2

Total = 58348.06

Graviloft Wall The total height of wall is 6.0m and base width of 1.8m.

The section is shown in Fig.3. The cost worked out per

running meter length of PCC wall in rupees as :

Item Qty. Rate Amount

Excavation 12. m3 659 7908

PCC 3.85 m3 4761 18329.8

RCC loft 0.84 m3 5615 4716.6

Reinforcement 22.46 Kg 48.39 1086.9

Total = 32041.38

For comparison PCC of M15 grade, RCC Concrete M20

grade considered. However, items like disposing excavated

material, back filling, shuttering, expansion joint and weep

holes are not considered.

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R. J. Balwan &, Ajitkumar Kumbhar

Fig.1 R.C.C. Cantilever Wall Section

Fig.2 PCC Gravity Wall Section

Fig.3 PCC Graviloft Wall Section

OTHER POINTS COMPARED

Base Pressure – Uniform base pressure distribution on

both sides as against trapezoidal pressure distribution with

large variation in case of cantilever and gravity walls.

Factor of Safety – Factor of safety against overturning and

sliding is the same i.e. 2.0 and 1.5 respectively, which is as

per codal requirement.

Time of Construction – Due to use of this technique

nearly 40% less time required as compared to gravity and

cantilever retaining walls.

Base Width – Lesser base width requires less land

compared to gravity and cantilever walls. This indicates

lesser land acquisition or more land available for user due

to less land locked.

Serviceability in Seismic Condition – Serviceable, Base

pressure remains positive during seismic conditions.

Ease of Construction and Supervision – No skilled

labour, neither special shuttering and supervision required.

Possibility of Wall Separation – Due to provision of lofts,

the wall becomes an integral part of backfill soil, resulting

in nhanced stability.

CASE HISTORIES Following is the list of works where the Graviloft

technology is adopted successfully. This technology

implemented for maximum wall height up to 26 m.

1) Wings walls of Aqueduct on Banda branch canal.

( Fig. 4)

Fig.4 Wings wall of Aqueduct

2) Wings of walls of Box Culvert at Tilari project

3) Guide walls at Lendi project

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Graviloft Retaining Wall : A Case Study

4) Divide walls and Guide walls at Amalibari M.I.

Tank

5) Guide walls at Vishnupuri barrage project

6) MSETC sub-stations

7) R.O.B., Pune (Fig. 5)

8) Foriculture Park, Talegaon (Fig. 7)

And so forth.

Fig.5 R.O.B., Pune

Fig.6 Wall at Kondawa, Pune

Fig. 7 Park at Talegaon

CONCLUSION Cost comparison analysis shows that the use of Graviloft

technology is cost saving solution to retain earthwork.

Graviloft wall has been constructed at many places

successfully.

ACKNOWLEDGEMENT The paper is published with the permission of Prof. D. R.

Phatak, who owns the Intellectual Property Rights for the

technology evolved. The authors are grateful to him for

giving encouragement for writing this paper.

REFERENCES

1. Joseph E. Bowels, Foundation Analysis and

Design, Mcgraw Hill Book Company.

2. Narayan V. Nayak, Foundation Design Manual,

5th Ed., Dhanpat Rai Publications.

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