ANALYSIS OF SUBGRADE BEARING CAPACITY

BY USING GEOTEXTILE
Session 2015-2019

Project Supervisor
Engr. Atif Ali Khan
Co-Supervisor
Engr. M Umair Ashfaq

DEPARTMENT OF CIVIL ENGINEERING

NFC INSTITUTE OF ENGINEERING AND FERTILIZER RESEARCH, FAISALABAD
PRESENTED BY
• Hussain Sajid (Group Leader) 2015-UET-NFC-TECH-CIVIL-40
• Muhammad Awais 2015-UET-NFC-TECH-CIVIL-38
• Muhammad Noman 2015-UET-NFC-TECH-CIVIL-36
• Shanawar Iqbal 2015-UET-NFC-TECH-CIVIL-35
• Mushtaq Ali 2015-UET-NFC-TECH-CIVIL-30
• Asad Ali 2015-UET-NFC-TECH-CIVIL-25
CONTENTS
Introduction
Literature Review
Objective
Methodology
Results and Discussion
Conclusion and Recommendation
References
INTRODUCTION
Geotextile utilization plays an important role in the construction of highways with
no additive layers, such as asphalt concrete or cement concrete, or in subgrade
layer which affects the bearing capacity of unbounded layers.
The laboratory experimental study was carried out to evaluate changes in the load
bearing capacity of reinforced soil with geotextile in highways roadbed
Geotextile with two different characteristics with different formations was used to
carry out the experimental study.
LITERATURE REVIEW
Subgrade
Soil classification system
AASHTO classification system
Basic characterization of subgrade performance
Subgrade strength parameter
California Bearing Ration (CBR)
Geotextile
SUBGRADE
SOIL CLASSIFICATION SYSTEMS
Unified Soil Classification System (USCS)
American Association of State Highway and Transportation Officials (AASHTO)
U.S Department of Agriculture (USDA)
Massachusetts Institute of Technology (MIT)
AASHTO CLASSIFICATION SYSTEM
BASIC CHARACTERIZATION OF SUBGRADE PERFORMANCE

Load Bearing Capacity

Volume Changes
SUBGRADE STRENGTH PARAMETERS
Bearing Capacity
• Safe Bearing Capacity
• Safe Net Bearing Capacity
• Ultimate Bearing Capacity
• Allowable Bearing Capacity
CALIFORNIA BEARING RATIO

Penetration Test
Developed by California Department of Transportation
Natural or Compacted soil
Water soaked or un-soaked conditions
Compared with standard values
Identification of bearing capacity of soil
CALIFORNIA BEARING RATIO (CONTD.)
CBR can be performed by two methods
• One Point Method
• Three Point Method
CALIFORNIA BEARING RATIO (CONTD.)
GEOTEXTILE
Geotextile, a newly emerging field in the civil engineering and other fields, offer
great potential in varies areas of application globally.
Geotextile plays a significant part in modern pavement design and maintenance
techniques.
Geotextile are ideal material for infrastructural works such as roads, harbors and
many others.
OBJECTIVE
The objectives of this project is to analysis the bearing capacity of subgrade by
adding geotextile into it. It includes:
Soil classification
Soil parameters identification
Determining the bearing capacity by CBR
METHODOLOGY

Methodology

Literature Experimental
Review work

Sample
Testing
Collection

Site Sieve Water Atterberg Modified Proctor California Bearing

Selection Analysis Content Limits Test Ration

Kashmir Pull,
Faisalabad
FORMATION OF GEOTEXTILE MOULD
Four mould prepared
 1st mould
 2nd mould
 3rd mould
 4th mould
1ST AND 2ND MOULD FORMATION
3RD AND 4TH MOULD FORMATION
RESULTS AND DISCUSSION
Sieve Analysis
Atterberg Limits
Soil Classification According To AASHTO
Modified Proctor Test
California Bearing Ratio
SIEVE ANALYSIS (CONTD.)
Results are satisfied
ASTM D 3282-93 (Reapproved 2004)
Wastage percentage is less than 3 %
PARTICLE SIZE DISTRIBUTION CURVE
Particle Size Distribution Curve
110
100
90
80
Percent Finer, %

70
60
50
40
30
20
10
0
100 10 1 0.1 0.01
Particle, D. mm
ATTERBERG LIMITS
Liquid Limit
Plastic limit
Plasticity index
LIQUID LIMIT
The moisture content at which any increase in the moisture content will cause a
plastic soil to behave like liquid.
ASTM D 4318
L.L = w x (N/25)0.121
LIQUID LIMIT (CONTD.)
Sample No. 1 2
Can No. L.L-1 L.L-2
Wt. of Can (gm) 6.14 6.42
Wt. of Can + Wet Soil (gm) 23.54 24.51
Wt. of Can + Dry Soil (gm) 19.93 20.72
Wt. of Dry Soil 13.79 14.3
Wt. of water 3.61 3.79
Water Content % 26.18 26.50
No. of Blows 36 33
Liquid Limit 27.36 27.41
Avg. Liquid Limit 27.38
PLASTIC LIMIT
Plastic limit is the water content in clay soil below Which it stop to behave like a
plastic material.
• ASTM D 4318
PLASTIC LIMIT (CONTD.)
Sample No. 1 2
Can No. P.L-1 P.L-2
Wt. of Can (gm) 6.92 6.11
Wt. of Can + Wet Soil (gm) 12.69 12.91
Wt. of Can + Dry Soil (gm) 11.7 11.84
Wt. of Dry Soil 4.78 5.73
Wt. of Water 0.99 1.07
Water Content % 20.71 18.67
Avg. Plastic Limit 19.69
RELATIONSHIP B/W L.L AND P.L
PLASTICITY INDEX
The plasticity index (PI) is a measure of the plasticity of a soil. The plasticity index
is the size of the range of water contents where the soil exhibits plastic properties.
Used for AASHTO classification of soil
• Plastic Index = Liquid Limit – Plastic Limit
• P.I = 27.38 – 19.69 = 7.69
AASHTO SOIL CLASSIFICATION
Following parameters are used to classify the soil according to AASHTO
Sieve analysis percent passing
Characteristics of fraction passing
AASHTO SOIL CLASSIFICATION (CONTD.)
 Group Classification
• A-2
 Sub-Group
• A-2-4
 Usual types of significant constituent materials
• Silty or clayey gravel and sand
 General rating as subgrade
• Good (useable)
MODIFIED PROCTOR TEST
Compaction test
Modified AASHTO standards
Optimum moisture content identification

Project : Final Year Project

Descripton of Soil: A-2-4 (Silty or clayey gravel and sand)
Blows/Layer:- 25 No. of Layers:- 5 Wt. of Rammer:- 4.5kg
Mould Dimensions Data. 10 Cm Ht. 11 Cm Vol. 863.5 Cm3
MODIFIED PROCTOR TEST
Following parameters are used to identifying the optimum water content of soil
 Water content determination
 Density determination
OPTIMUM WATER CONTENT
2.10

2.08
Dry density kN/m3

2.06

2.04

2.02

2.00

1.98

1.96

1.94
13.20 13.40 13.60 13.80 14.00 14.20 14.40 14.60 14.80 15.00 15.20
water Content.%
CALIFORNIA BEARING RATION
Simple: without reinforcement
1st mould: one layer of 120 g/m2 geotextile
2nd mould: two layers of 120 g/m2 geotextile
3rd mould: one layer of 300 g/m2 geotextile
4th mould: two layers of 300 g/m2 geotextile
CALIFORNIA BEARING RATION (CONTD.)
Proving Dial Guage Reading at
Swelling Water Content CBR Values (%)
Sample/Mould Penetration
Name
% % 2.5 mm 5 mm 2.5 mm 5 mm

Simple 2 25.92 4.5 6.6 7.9 7.7

1st Mould 1.4 21.1 6.5 9 11.4 10.5

2nd Mould 1.1 19.9 7.2 9.9 12.6 11.5

3rd Mould 0.71 18.1 6.8 9.6 11.9 11.2

4th Mould 0.28 16.1 9 12 15.7 14

CALIFORNIA BEARING RATION (CONTD.)
CBR COMPARISON
Comparison of CBR CBR Values (%) 2.5 (mm) Comparison of CBR CBR Values (%) 5 (mm)
18

16

14

12

10

0
S IMP LE 1S T MOULD 2ND MOULD 3R D M OULD 4TH M OULD
CONCLUSION
The resistance against loading increased with the utilization of geotextile.
CBR values indicated better response.
Maximum CBR is on the 300 g/m2
With 120 g/m2 the bearing capacity increased to 1.6 to 2 times more
With 300 g/m2 the bearing capacity increased to 1.8 to 2.2 times more.
RECOMMENDATIONS
Utilization of geotextile if bearing capacity is low.
No need of additive layers.
Geotextile can offer other particular uses in development of transportation
engineering and can be used for further experimental studies of different soils.
REFERENCES (BOOKS)
Aziz Akbar, Ch. 4 Soil Classification, Fundamentals of soil mechanics
Dr. K.R. Arora, Ch 19 Highway Soil Classification, Soil Mechanics and
Foundation Engineering
McGraw Hill and Das B.M., Stability of Soil, Advanced Soil Mechanics.
Athanssios Nikolaides, Compaction Test, Highway Engineering
C.S Papacostas and Panac Prevedours, California Bearing Ratio, Transportation
Engineering and Planning.
REFERENCES (STANDARDS)
D 3282–93 Standard practice for classification of soil and soil aggregates for
highway construction purpose.
ASTM D 4318 Standard test method for determination of liquid limit, Plastic
limit and Plasticity Index of soil.
ASTM D-1557 and AASHTO T180-D Modified test method for Compaction.
D 1883-99 Standard test method for CBR for laboratory Compacted Soil.
REFERENCES (WEB)
 www.books.google.com.pk/geotechnicalengineeringbyc.venkatrah
 www.geogroup.com.za/geotechnical-investigation/geotechnical-investigationsthesting
 www.nptel.ac.in
 www.civilengineers.pk
 www.thecontructor.org/geotechnical
 www.academia.edu
 www.dk-geosynthetics.com
 www.engineersdaily.com