PAVEMENT DESIGN Using Geosynthetic Karnala Bpcl

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1.0 INTRODUCTION

M/s. Bharat Petroleum Chemicals Private Ltd. plans construction of driveway at NRO Karnala,

Virar, Dist.:- Palghar. Dr. Ganesh S. Kame was appointed to review soil report and design the

driveway. This report includes the design considerations engineering recommendations for the

proposed driveway.

2.0 DESIGN OF DRIVEWAY

Judging from sides of the trial pit excavations, subsurface profile at the site consists of residual

soils overlying stiff silty sand. Groundwater table was not encountered at a depth of approximately

1.5 m in the trial pit. As mentioned in the report, stiff silty clay was encountered at a depth more

than 0.5 m below ground surface at this site. Maximum net allowable soil bearing pressure of

10 t/m2is permitted for the development.

Based on the performance of existing designs and using analytical approach, IRC offers

simple design charts and a catalogue of pavement designs (Fig. 1). The pavement designs

are given for subgrade CBR values ranging from 2 per cent to 10 per cent and design traffic

ranging from 1 msa to 150 msa for an average annual pavement temperature of 35°C.

In this report similar approach is adopted for construction of driveway. A typical WBM is

shown in Fig. 2.

Fig. 1 Pavement Thickness as per IRC 37:2012



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Fig. 2 Typical WBM

Based on existing soil condition at site and the IRC recommendation the value of CBR canadopted between 3-5. Table 1 gives typical values as per IRC.

Table 1 Some Typical values

Classification CBR MR (psi) Typical Description

Good ≥ 10 20,000 Gravels crushed stone and sandy soils. GW,

GP, GM, SW, SP, SM soils are often in this

category

Fair 5 - 9 10,000 Clayey gravel and clayey sand, fine silt soils.

GM, GC, SM, SC soils are often in this

category.

Poor 3 - 5 5,000 Fine silty sands, clays, silts, organic soils.

CH, ML, MH, CM, OL, OH soils are often in

this category

3.0 WORKED-OUT EXAMPLES ILLUSTRATING THE DESIGN METHOD

3.1 Bituminous Pavements with Untreated Granular Layer

Design the pavement for construction of a new flexible pavement with the following data:

Bituminous layer

Granular Base

Granular Sub-base

Subgrade

Treated asGranular Layer

Bituminous Surfaceing with

Granular Base and Granular Sub-base



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DATA

(i) Four lane divided carriageway

(ii) Initial traffic in the year of completion of construction = 5000 CV/day

(Sum of both directions)

(iii) Percentage of Single, Tandem and Tridem axles are 45 per cent, 45 per cent and 10 per

cent respectively

(iv) Traffic growth rate per annum = 6.0 per cent

(v) Design life = 20 years

(vi) Vehicle damage factor = 5.2

(Based on axle load survey)

(vii) CBR of soil below the 500 mm of the subgrade = 3 per cent

(viii) CBR of the 500 mm of the subgrade from borrow pits = 10 per cent

DESIGN CALCULATIONS

(i) Lane Distribution factor = 0.75

(ii) Initial traffic = 2500 CVPD assuming 50 per cent in each direction.

(iii) Vehicle Damage Factor (VDF) computed for the traffic = 5.2.

(iv) Cumulative number of standard axles to be catered for in the design

N =

2500 x 365 x[(1 + 0.06)20-1]

x 0.75x5.2 = 131msa0.06

(v) CBR of the embankment material = 3 per cent,

CBR of 500 mm of subgrade = 10 per cent,

Effective CBR of the subgrade from (IRC) = 7 per cent



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Design resilient modulus of the compacted subgrade = 17.6(7)0.64

= 62 MPa

(vi) Thickness of granular layers: WMM = 250 mm, GSB = 230 mm

Resilient modulus of granular layer = 0.2 x (480)° 45 x 62 = 200 MPa.

The upper 100 mm of the cemented sub-base should be open graded so that its permeability

is about 300 mm/day or higher for quick removal of water entering from the surface.

4.0 GEOSYNTHETICS FOR CONSTRUCTION ROADS

Geosynthetic system solutions are used in the construction of roadways and trafficked areas.

The coarse grained cover soil interlocks with the Geogrid (grid apertures ≥ 28 mm) creating a

bond. This immediate interlock provides a horizontal force transfer which increases the bearing

capacity of the soil due to the high force absorption with low elongation. The required bearing

capacity can be achieved without additional expensive soil exchange, and in some cases, the base

course thickness can be reduced.

5.0 FINAL DESIGN USING GEOGRID

The scheme for proposed work is as shown in Fig. 3 below.

Fig. Scheme for proposed work

Dr. Ganesh S. Kame

PhD Geotechnical Engg., IIT

Bombay

(Consulting officer)

WBM 130 MM AS PER IRC GUIDELINES

SUB BASE COURSE 230 AS PER IRC GUDELINES

COMPACTED SUBGRADE

PAVER BLOCK OF APPROVED MAKE

EXTRUDED GEOGRID OF APPROVED MAKE

NONWOVEN GEOTEXTILE OF APPROVED MAKE

BASE COURSE 200 mm OR AS PER IRC GUIDELINES



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Table 2 Details for WBM as per IRC 19:2005

6.0 WATER BOUND MACADAM SUB BASE/BASE COURSE

The sub-base course shall consist of one or more layers, each or 100 mm compacted thickness.

The base course shall consist of one or more layers, each of 75 mm compacted thickness.

6.1 Stone Aggregate for WBM

The coarse aggregate shall be hard, crushed or broken stone metal from quarries approved by

Engineer-In Charge, it shall be hard durable and free from flat elongated, Soft and disintegrated

particles. It shall not have excess of dirt and other objectionable matter. The quality, size, and

grading of the coarse aggregate shall be conforming to IRC 19: STD Spec and code of practice

for WBM.

6.1.1 Grading of the coarse aggregate for the sub-base course

The grading of the coarse aggregate for the sub-base course shall be as follows:



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6.1.2 Grading of the coarse aggregate for the base course

The grading of the coarse aggregate for the base course shall be as follow:

6.1.3 Physical requirement of coarse aggregates for sub-base course

Physical requirement of coarse aggregates for sub-base course shall be as below: i)Los Angles

Abrasion Value-60% (Maximum) Or ii)Aggregate Impact Value -50% (Maximum)

6.1.4 Physical requirement of coarse aggregates for base course

Physical requirement of coarse aggregates for base course shall be as below: i)Los Angles

Abrasion Value-50% (Maximum) Or Aggregate Impact Value- 40% (Maximum) ii) Flakiness

index value -15% (Maximum)

Samples of test shall be representative of the material to be used and collected as per IS: 2430.

7.0 WBM ROAD CONSTRUCTION PROCEDURE

WBM Stands for Water Bound Macadam which is the most commonly used road construction

procedure for over more than 190 years.Pioneered by Scottish Engineer John Loudon McAdam

around 1820 Macadam is a type of Road Construction. The broken stones of base and surface

course,if any are bound by the stone dust is presence of moisture is called WBM Roads.

Macadam means the pavement base course made of crushed or broken aggregate mechanically

interlocked by rolling and the voids filled with screening and binding material with the assistance

of water.WBM may be used as a sub-base,base or a surface course.The thickness of each

compacted layer of WBM ranges from 10cm to 7.5cm depending on size and the gradation

of aggregate used.



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7.1 Construction Procedure:

1.Prepare the foundation for receiving the WBM course.

2. Lateral confinement may be done by compacting the shoulder to advance, to a thickness equal

to that of the compacted WBM layer and by trimming the inner side vertically.

3. Spreading of Coarse Aggregate.

4.Compaction of coarse aggregate is done by wheeled power roller of capacity 6 to 10 tonnes or

alternately by an equivalent vibratory roller.



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5.Dry screening is applied gradually over the surface to fill the interstices in these.

6.The surface is sprinkled with water,swept and rolled.

7.Binding material is applied at a uniform and slow rate at two and more layers.

8.WBM Coarse is allowed to set overnight.



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8.0 REFERENCES

1) Foundation Analysis and Design, J.E. Bowles, McGraw Hill Publication, 5th Edition, 1996.

2) Soil Mechanics and Foundation Engineering, K.R. Arora, Standard Publishers Distributors,

Fourth Edition, 1997.

3) Soil Mechanics in Engineering Practice, 2nd

Edition, Terzaghi K. and Peck R. B., John Willey

and Sons, 1967.

4) IRC 27:2012

5) IRC 19:2005

6) Geosynthetic Design and Construction Guidelines, Publication No FHWA HI-95-038

http://www.fhwa.dot.gov/engineering/geotech/pubs/011431.pdf

6) http://www.dot.ca.gov/hq/maint/Pavement/Offices/Pavement_Engineering/PDF/Subgra

de_Enhancement_Geosynthetic_Guide_09212013.pdf

7) http://www.wsdot.wa.gov/publications/manuals/fulltext/M22-01/630.pdf

8) Design and Practice of Geosynthetic-Reinforced Soil Structures, Professor Dov Leshchinsky

PAVEMENT DESIGN Using Geosynthetic Karnala Bpcl

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