experimental study on infiltration using double-ring
TRANSCRIPT
EXPERIMENTAL STUDY ON INFILTRATION USING DOUBLE-RING
INFILTROMETER
MORAMMAD FARHAN BIN SALLEH
A thesis submitted in fulfillment
of the requirements for the
award of the degree of
Bachelor of Civil Engineering
Faculty of Civil & Environmental Engineering
University College of Engineering and
Technol Malaysia
NOVEMBER, 2006
ABSTRACT
Kolej Universiti Kejuruteraan & Teknologi Malaysia (KUKTEM) is located in
Pahang Darul Makniur. Infiltration can be define as the rate of water soaking into the
soil and the unit used to calculate the infiltration rate is mm/hour. The calculation of the
infiltration rate entering the soil, a double-ring infiltrorneter is used for the experiment.
Three locations have been selected as the study area which is nearby the laboratory of
Civil and Environmental Faculty, in front of KUKTEM's mosque and KUKTEM's
football field. For each location, three points have been chosen based on the distance of
the point with distance between 5m-lOrn as an experimental point. After performing the
experiment, soil samples have been gathered and analyzed in the laboratory using the
sieve analysis experiment. The calculation that is using in this experiment is Horton's
Equation. The analysis indicated that the soil for the three selected areas is sandy soil.
The infiltration rate at KUKTEM's football field is lower compared to the other two
selected areas.
V
ABSTRAK
Kolej Universiti Kejuruteraan dan Teknologi Malaysia (KUKTEM) terletak di
Pahang Darul Makmur. Penyesapan bermaksud kadar air masuk ke dalam tanah dan unit
yang digunakan untuk mengira kadar resapan ialah mm/jam. Pengiraan kadar resapan air
ke dalam tanah, alat double-ring infiltrometer digunakan untuk eksperimen. Tiga tempat
telah dipilih sebagai kawasan kajian iaitu berdekatan makmal kejuruteraan awam dan
sumber alam, depan masjid KUKTEM dan padang bolasepak KUKTEM. Untuk setiap
kawasan kajian, tiga tempat dipilih mengikut jarak antara tempat iaitu jarak antara 5m-
10m sebagai kawasan eksperimen. Selepas eksperimen, sampel tanah setiap eksperimen
diambil dan dianalisis di makmal dengan ekperimen ayakan. Pengiraan yang digunakan
dalam eksperimen un ialah persamaan Horton. Analisis menunjukkan tanah ketiga-tiga
kawasan kajian bercirikan pasir. Kadar penyesapan air ke tanah di kawasan padang
bolasepak KUKTEM Iebih rendah berbanding dengan di dun kawasan kajian yang lain.
vi
TABLE OF CONTENTS
CHAPTER SUBJECT PAGE
FRONT PAGE i DECLARATION DEDICATION ACKNOWLEDGEMENT iv
ABSTRACT v ABSTRAK vi
TABLE OF CONTENTS vii
LIST OF TABLES x LIST OF FIGURES xi LIST OF SYMBOLS xiii
LIST OF APPENDICES xv
CHAPTER I INTRODUCTION
1.1 General i 1.2 Problem statement 2 1.3 Objective 3 1.4 Scope of study 3
CHAPTER II LITERATURE REVIEW
vi'
2.1 Infiltration 4
viii
2.2 Factors affect infiltration 5
2.2.1 Soil properties 5
2.2.2 Residence time 7
2.2.3 Infiltration rate 8
2.2.4 Vegetation 8 2.3 Engineering Classification of Soil 8 2.4 Particle-Size Distribution Curve 9 2.5 Unified Soil Classification System 10 2.6 Time of Ponding 15 2.7 Infiltration method 16
2.7.1 Horton equation 16
2.7.2 Modified Horton equation 18
2.7.3 Green-Ampt equation 1
2.7.4 Holtan equation 21 2.8 Double-ring infiltrometer 23
2.8.1. Introduction 23 2.9 Summary 25
CHAPTER III METHODOLOGY
3.1 Introduction 27 3.2 Methodology 28 3.3 Study area 29 3.4 Infiltration equation 31 3.5 Laboratory Test 31 3.6 Sieve analysis 31
3.6.1 Apparatus 32
3.6.2 Procedure 32 3.7 Field infiltration test 33
3.7.1 Apparatus 34
3.7.2 Procedure 35
CHAPTER IV RESULT AND ANALYSIS
4.1 Introduction 36 4.2 Analysis of Data 37
4.2.1 Sieve Analysis 37 4.2.2 Infiltration rate 43
4.3 Summary of Analysis 50
CHAPTER V CONCLUSION AND RECOMMENDATION
5.1 Introduction 51 5.2 Conclusion 52 5.3 Recommendation 53
REFERENCES 54
APPENDIX A - C 56
ix
LIST OF TABLES
TABLE 'TITLE PAGE
2.1 Unified Soil Classification (USC) System 11
(from AS'TM D 2487), 2003
2.2 Flowchart group names for gravelly and sandy soil 14
2.3 Horton Parameters for Bluegrass Turf 18
2.4 Tentative Estimates of the Vegetation Parameter a in the 22
Infiltration Equation
5.1 Table of Horton Equation for Location A, B and C 52
x
LIST OF FIGURES
NO.FIGIJRE TITLE PAGE
2.1 Plasticity chart 12
2.2 Infiltration curve 17
2.3 Doublc4ting Infiltrometer Equipment 23
3.1 Flow chart of methodology 28
3.2 Nearby the Civil and Environmental Engineering Lab 29 3.3 In front of KUKTEM's mosque 30
14 KUKTEM's football field 30
3.5 Sieve Analysis Mechanical Shaker 32
Doublc'Ring Infiltrometer 34
4.1 Particle size distribution for sample Al at location A 38 4.2 Particle size distribution for sample A2 at location A 39 4.3 Particle size distribution for sample A3 at location A 39 4.4 Particle size distribution for sample B at location B 40 4.5 Particle size distribution for sample 132 at location B 40 4.6 Particle size distribution for sample 133 at location B 41 4.7 Particle size distribution for sample C at location C 41 4.8 Particle size distribution for sample C2 at location C 42 4.9 Particle size distribution for sample C3 at location C 42 4.10 Infiltration curve for sample Al at location A 45 4.11 Infiltration curve for sample A2 at location A 46 4.12 Infiltration curve for sample A3 at location A 46 4.13 Infiltration curve for sample BI at location 13 47 4.14 Infiltration curve for sample B2 at location B 47 4.15 Infiltration curve for sample B3 at location 8 48
xi
xli
4.15 Infiltration curve for sample B3 at location B 48
4.16 Infiltration curve for sample Cl at location C 48
4.17 Infiltration curve for sample C2 at location C 49
4.18 Infiltration curve for sample C3 at location C 49
LIST OF SYMBOLS
D10 = Effective size
C = Uniformity coefficient
D60 = diameter corresponding to 60% finer.
C = Coefficient of gradation
= Sorting coefficient
t ponding time
I time
= infiltration capacity, (mm/hr)
ff = final infiltration capacity, (mm/hr)
fo initial infiltration capacity, (mm/hr)
k = exponential decay constant, (hr')
t time from beginning of rainfall. (hr)
K = hydraulic conductivity
H0 depth of flow ponded at the surface
Sw = effective suction at the wetting front
L = depth from the surface to the wetting front
f infiltration rate
F = accumulative infiltration
xlii
A parameter
xiv
B parameter
a he infiltration capacity [(inihr)/in."] of the available storage (index of
surface-connected porosity)
S. = available storage in the surface layer (A -horizon in agricultural soils, that is
about the first six in.) (in. of water equivalent)
mm/hr = millimeter/hour
mm = millimeter
hr =hour
LIST OF APPENDICES
APPENDIX TITLE PAGE
A.l Infiltration data for sample Al at location A 57
A.2 Infiltration data for sample A2 at location A 58
A.3 Infiltration data for sample A3 at location A 60
A.4 Infiltration data for sample B! at location B 61
A.5 Infiltration data for sample B2 at location B 62
A.6 Infiltration data for sample B3 at location II 64
A.7 Infiltration data for sample C at location C 66
A.8 Infiltration data for sample C2 at location C 67
A.9 Infiltration data for sample C3 at location C 68
B. 1 Sieve Analysis data for sample Al at location A 70
B2 Sieve Analysis data for sample A2 at location A 70
B.3 Sieve Analysis data for sample A3 at location A 71
B.4 Sieve Analysis data for sample 131 at location B 71
B.5 Sieve Analysis data for sample 132 at location B 72
B4 Sieve Analysis data for sample B3 at location B 72
B.7 Sieve Analysis data for sample C at location C 73
B.8 Sieve Analysis data for sample C2 at location C 73
B.9 Sieve Analysis data for sample 0 at location C 74
C. 1 Infiltration curve at location Al 76
C.2 Infiltration curve at location A2 76
C.3 Infiltration curve at location A3 77
C.4 Infiltration curve at location BI 77
C.5 Infiltration curve at location B2 78
C.6 Infiltration curve at location 133 78
xv
xvi
C.7 Infiltration curve at location C
79
C.8 Infiltration curve at location C2
79
C.9 Infiltration curve at location C3
80
CHAPTER I
INTRODUCTION
1.1 General
Infiltration is the process when the water soaking into the soil. Infiltration rate is
simply how fast water enters the soil and is usually measured in inches or millimeters
per hour. This rate depends on soil texture (amount of sand, silt, and clay) and soil
structure, Soils in good condition have well developed structure and continuous pores to
the surface. As a result, water from rainfall or snowmelt readily enters these soils.
Soil is a reservoir that stores water for plant growth. The water in soil is
replenished by infiltration. The infiltration rate can be restricted by poor management.
Under these conditions, the water does not readily enter the soil and it moves down
slope as runoff or ponds on the surface, where it evaporates. Thus, less water is stored in
the soil for plant growth, and plant production decreases, resulting in less organic matter
in the soil and weakened soil structure that can further decrease the infiltration rate.
Another important of infiltration is in construction. The infiltration experiment
will be done at any area to definite that the area safe for construction. The results
summarize about the texture and porosity of the soils. Good soil structure improves
infiltration. Soils with good structure have more pores for the movement of water than
soils with poor structure.
2
Commonly used methods for determining infiltration capacity are hydrograph
analyses and inflitrometer studies. Infiltrometers are usually classified as rainfall
simulators or flooding devices. In the former, artificial rainfall is simulated over a test
plot and the infiltration is calculated from observations of rainfall and runoff, with
consideration given to depression storage and surface detention (W. K. Johnson, 1974).
Infiltrometers are usually tubes and rings inserted in the ground level of soil.
Water is applied and maintained at a constant level and observations are made of
the rate of replenishment required (W.Viessman and Jr.Gary L.Lewis, 2003). Estimates
of infiltration based on hydrograph analyses have the advantage over infiltrometers of
relating more directly to prevailing conditions of precipitation and field. Several
methods have been developed and are in use (Charley, A. Pabst, and J.Peters, 1995).
1.2 Problem Statement
In this infiltration study, the infiltration test will determine the types of soil in
KUKTEM area. The result from the experiment will analyze the types of soil and the
effects for the development at the surrounding KUKTEM area. This study will
determine how fast the water infiltrates into the soil in KUKTEM area. So we will know
the properties of soil in the area which the rates of infiltration that can prevent flood
from happen and for the future development. For the preventing flood happen, the soil
Properties must be study before any development will be constructed at KUK'II M area.
3
1.3 Objective
The objectives of study are;
I. To determine types of soils for study area.
2. To obtain infiltration curve using Horton's Equation.
3. To determine the infiltration parameter using Horton's Equation.
4. To compare the values of infiltration parameter among different locations.
1.4 Scope of study
This study will be used Double-Ring Infiltrometer that is prepared by Faculty of
Civil and Environmental Engineering KUKTEM. Three main locations are chosen to
collect the data. The locations are nearby the Civil and Environmental Engineering Lab,
in front of KUKTEM's mosque and KUKTEM's football field. The calculation for
infiltration measurement in this study is using Horton's Equation.
CHAPTER II
LITERATURE REVIEW
21 Infiltration
Infiltration process is the largest process of rainfall losses in area. The term
infiltration refers to the process by which rainwater passes through the ground surface
and fills the pores of the underlying soil ( A.Osman Akan and Robert J. Houghtalen,
1992). Surface and subsurface of soil conditions influence the infiltration rates. The
surface conditions determine the availability of water, while the subsurface conditions
govern the ability of the available water to infiltrate (A.Osman Akan and Robert J.
Houghtalen, 1992). The rate of rainfall means the availability of water at the ground
surface, The infiltration capacity means as the maximum rate at which water can
infiltrate into the soil. Its mean the ability of available water to infiltrate.
Infiltration is the process when the water penetrating or enter into the soil from
the ground surface. There are many factors that influence the infiltration rate such as the
condition of the soil surface and its vegetative cover, the properties of the soil, such as
its porosity and hydraulic conductivity, and the current moisture content of the soil. Soil
strata with different physical properties may overlay each other, forming horizons; for
example, a silt soil with relatively high relatively high hydraulic conductivity may
overlay a clay zone of low conductivity. Also, soils exhibit great spatial variability even
within relatively small areas such as a field. As a result of these great spatial variations
and the time in soil properties that occur as the soil moisture content changes, infiltration
5
is a very complex process that can be described only approximately with mathematical
equations (Veil Te Chow, 1988).
2.2 Factors affect infiltration
The proportion of water from rainfall or snowmelt that enters the soil depends on
residence time (how long the water remains on the surface before running oft) and the
infiltration rate. These are affected by vegetation and many soil properties.
2.2.1 Soil properties
The properties that affect infiltration and cannot be readily changed by
management include:
i. Texture
Water moves more quickly through the large pores and spaces in a sandy soil
than it does through the small pores in a clayey soil. Where the content of
organic matter is low, texture plays a significant role in the susceptibility of the
soil to physical crusting.
ii. Clay mineralogy
Some types of clay develop cracks as they dry. These cracks rapidly conduct
water to the subsurface and seal shut once the soil is wet.
iii. Minerals in the soil
High concentrations of sodium tend to inhibit the development of good structure
and promote the formation of surface crusts, which reduce the infiltration rate.
Calcium improves soil structure.
iv. Soil layers
Subsurface soil, including a subsoil of dense clay, cemented layers, and highly
contrasting layers, such as coarse sand over loam, can slow water movement
through soil and thus limit infiltration.
V. Depth
Soil depth controls how much water the soil can hold. When soil above an
impermeable layer, such as bedrock, becomes saturated, infiltration ceases and
runoff increases. The properties that affect infiltration and can be readily
changed by management or a shift in vegetation.
vi. Organic matter and soil biota
Increased plant material, dead or alive, generally improves infiltration. As
organic matter is broken down by soil organisms, it binds soil particles into
stable aggregates that enhance pore space and infiltration.
vii. Aggregation and structure
Good soil structure improves infiltration. Soils with good structure have more
pores for the movement of water than soils with poor structure. if aggregates are
stable, the structure remains intact throughout a rainstorm.
viii. Physical crusts
Physical crusts form when poorly aggregated soils are subject to the impact of
raindrops and/or to ponding. Particles broken from weak aggregates can clog
pores and seal the surface, thus limiting water infiltration.
7
ix. Biological crusts
Biological crusts can eithernerease or reduce the infiltration rate. Theft effect on
the infiltration rate depends on many other factors, including soil texture.
X. Pores and channels
Continuous pores connected to the surface convey water. Such organisms as
earthworms, ants, and termites increase the number of pores. Termites, however,
can decrease the infiltration rate by reducing the amount of litter cover, and some
ant species seal the surface around their nests.
xi. Soil density
A compacted zone close to the surface restricts the entry of water into the soil
and often results in surface ponding. Increased bulk density reduces pore space
and thus the amount of water available for plant growth.
xii. Water-repellent layer
As shrubs and an underlying thick layer of litter bum in a hot fire, very high
temperatures can occur directly beneath the shrubs. The heat forces a gas from
the burning plant material into the soil. When it cools, the gas forms a water-
repellent layer that limits infiltration. This feature is temporary, although it may
persist for a number of years. Some soils can be slightly water repellent when
dry.
2.2.2 Residence time
The length of time that water remains on the surface depends on the slope, the
roughness of the soil surface, and obstructions to overland flow, such as plant bases and
litter. Consequently, plant communities with large amounts of basal area cover, such as
8
grasslands tend to slow runoff more than communities with small amounts of basal
cover,, such as shrub lands.
2.2.3 Infiltration rate
The infiltration rate is generally highest when the soil is dry. As the soil becomes
wet, the infiltration rate slows to the rate at which water moves through the most
restrictive layer, such as a compacted layer or a layer of dense clay. Infiltration rates
decline as water temperature approaches freezing. Little Or no water penetrates the
surface of frozen or saturated soils.
2.2.4 Vegetation
A high percentage of plant cover and large amounts of root biomass generally
increase the infiltration rate. Different plant species have different effects on infiltration.
The species that form a dense root mat can reduce the infiltration rate. In areas of and
and semiarid rangeland, the infiltration -limiting layer commonly is confined to the top
few millimeters of the soil, particularly in the open spaces between plant canopies.
These areas receive few inputs of organic matter, which build soil structure. Also, the
impact of raindrops in these areas can degrade soil structure and form physical crusts.
2.3 Engineering Classification of Soil
Different soils with similar properties may be classified into groups and sub-
groups according to their engineering behavior. Classification systems provide a
common language to concisely express the general characteristics of soils, which are
infinitely varied, without detailed descriptions. Currently, two elaborate classification
systems are commonly used by soils engineers. Both systems take into consideration the
particle-size distribution and Atterberg limits. They are the American Association of
State Highway and Transportation Officials (AASHTO) classification system and the
Unified Soil classification system. The AASHTO classification system is used mostly by
state and country highway departments. Geotechnical engineers generally prefer the
Unified system.(Braja M.Das,2006)
2.4 Particle-Size Distribution Curve
A particle-size distribution curve can be used to determine the following four
parameters for a given soil.
1. Effective size (L)jo): This parameter is the diameter in the particle-size
distribution curve corresponding to 10% finer. The effective size of a granular
soil is a good measure to estimate the hydraulic conductivity and drainage
through soil.
2. Uniformity coefficient (Ce) This parameter is defined as
cu = /to (2l)
D10
where D60 = diameter corresponding to 60% finer.
10
3. Coefficient of gradation (Ce) This parameter is defined as
930
(2.2) D60 X D10
4. Sorting coefficient (So) : This parameter is another measure of uniformity and is
generally encountered in geologic works and expressed as
So = Jp (2.3)
D25
The sorting coefflecient is not frequenly used as a parameter by geotechnical
engineers. (Braja M. Das, 2006)
23 Unified Sil Classification System
The original form of this system was proposed by Casagrande in 1942 for use in
the airfield construction works undertaken by the Army Corps of Engineers during
World War H. In cooperation with the U.S Bureau of Reclamation, this system was
revised in 1952. At present, it is used widely by engineers ( ASTM Test Designation D-
2487). The Unified Soil Classification System is presented in Table 2.1. -
11
Table 2.1 : Unified Soil Classification (USC) System (from ASTM D 2487), 2003
r Divisions MajorGroupSymbol
Gravels Clean GW Cu> 4 and I <Cc < 3c 50% or more Gravels <4/ > of course
Gravels GM P1<4 or plots below "A" line fraction
Course-Grained retained on with ______ 11)
GC P1>7 and plots on or above "A" Soils the 4.75 mm Fines More than 50% (No. 4) sieve line ((Figwc 2.1) retained on the O075mm Sands Clean SW Cu>6 and l<zCc<3c
s Cu <6 and/or 1 > Cc >3c (No 200) sieve 50% or more an
of course fraction passes Sands SM P1 <4 or plots below "A" line
the 475 with(Figure
SC P1>7 and plots on or above "A" (No 4) sieve Finesline (Figure 11)
CL P1<4 or plots on or above "A" line (Figure 2.1)
ML P1>7 and plots below "A" line Silts and Clays _______ (Figure 2.1) Liquid Limit 50% or less . ..
- limit - oven d Liquid dried Fine-Grained
OL
- <0.75
Soils -Liquid limit - not dried
More than 50% ___________________ _______ ; OL zone passes the 0.075 Tflffi CH P1 plots on or above "A"
(No. 200) sieve(Figure 2.1)
Silts and Clays MH P1 plots below "A" In -6
Liquid Limit greater than
(Figure)
Liquid limit = oven dried 50%
OHLiquid limit - not dried
OH zone
Highly Organic Soils PT Primarily organic matter, dark in colour and organic odor
Prefix: G Gravel, S Sand, M Silt, C Clay, 0 Organic Suffix: W Well Graded, P = Poorly Graded, M = Silty, L = Clay, LL < 50%, H = Clay, LL>5%