pragma catafgrlog technfgdfgical
TRANSCRIPT
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Pipelife Polska S.A.ul. Torfowa 4, Kartoszyno, 84-110 Krokowa
tel. (+48 58) 77 48 888, fax: (+48 58) 77 48 807, e-mail: [email protected]; www.pipelife.pl
CONTENTS
INDEX
1. INTRODUCTION1.1 INTRODUCTION OF PP PRAGMA SEWAGE SYSTEM
1.2 CHARACTERISTIC OF PRAGMA SYSTEM
2. HYDRAULIC DESIGN OF PRAGMA SYSTEM
2.1. GENERAL ASSUMPTIONS
2.2. GOVERNING FORMULAE
2.3 NOMOGRAPH 1
2.4 NOMOGRAPH 2
2.5 NOMOGRAPH 3
3. SLOPES AND VELOCITIES OF FLOW INPRAGMA PIPES
4. STRESS AND STRENGTH ANALYSIS OFBURIED PRAGMA PIPES4.1 INTERACTION BETWEEN THE PIPE AND THE
SURROUNDING SOIL
4.2 METHOD OF CALCULATION
4.3 LOAD
4.4 ULTIMATE LIMIT STATE MODEL
4.5 ULTIMATE LIMIT STATE MODEL STRAIN
4.7 RELATIVE STRAIN
5. EARTHWORKS5.1 GENERAL CONSIDERATIONS
5.2 BEDDING CONDITIONS
5.3 SIDEFILL, INITIAL BACKFILL AND FINAL BACKFILL
6. INSTALLATION OF PRAGMA PIPES6.1 CONNECTION OF PRAGMA-PRAGMA PIPES
6.2 CUTTING PIPE - MOUNTING SEALING RING
6.3 CONNECTION OF PRAGMA PIPE (SPIGOT) WITH PVC PIPE
6.4 CONNECTION OF PRAGMA PIPE (SOCKET) WITH SMOOTH
PVC PIPE (SPIGOT)
6.5 CONNECTION OF PRAGMA TO CONCRETE
CHAMBER(SOCKET)
7. PRODUCT RANGE
8. LITERATURE
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1
INTRODUCTION OF PP PRAGMA SEWAGE SYSTEM
INTRODUCTIONOFPPPRAGMA
1.2 CHARACTERISTIC OF PRAGMA SYSTEM
The Pragma pipes have been designed
for sanitary and rainwater sewage sys-
tems. The pipes can be used in the
industrial sewage as jacket pipes for tel-
ecomunication cables as well as draingepipes for roads, dumping grounds etc.
The raw material used for Pragma pipes
production is polypropylene co-polymer.
Pragma pipes is a twin well pipes with
a smouth inside and profiled outside
walls.
The pipes own a real mounted in the
first corrugation valley.
The adapters allows to connect Prag-
ma pipes with smooth PVC pipes.
PP Pragma sewage system consists of:
Twin wall pipes with a socket in 3 and
6 meters lengths. Scope of diameters
160 - 630 mm and ring stiffness 8
kN/m2.
Full range of fittings.
1.1
INTRODUCTION
CHEMICAL RESISTANCEPragma pipes and fittings have high
chemical resistance both for aggres-
sive sewage and an enviroment.
RESISTANT TO HIGH
TEMPERATURES
Pragma pipes and fittings have a resist-
ant to high temperature up to 60oC for
constant flow and up to 95-100oC for
brief sewage passage.
IMPACT STRENGTH
Pragma pipes and fittings are crack
resistant, including temperatures below
0
o
C (up to -20
o
C) which makes transportand assembly easy in winter conditions.
RING STIFFNESS
Ring stiffness which for the entire range
of diameters equals 8 kN/m2 puts the
system in class T.
EASY TO CARRY
Pragma pipes and fittings are very light
and yet have high ring stiffness there-
fore they are easy to transport and place
which speeds up assembling.
EASY TO ASSEMBLEPragma pipes and fittings can be eas-
ily joined with smooth-wall PP and PVC
pipes and cladding can be applied inter-
changeably in each system.
EASY TO CUT
Pragma pipes can be cut to any length
with the use of the simplest tools.
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cos ) cos )qn
Motion resistance on the pipe lenght are
calculated based on unitary hydraulic
gradient.Unitary hydraulic gradient for
closed pipes with a settled turbulent
motion is calculated based on Darcy-
Weisbach formula:
Hydraulic resistance coefficient () iscalculated based on Colebrook-White
formula:
The Bretting formula for pipes flowing
partly full:
Pipelife proposes to use the following
values of k for Pragma pipes:
k = 0.00025 m, for main sewers without
special structures, equipment and any,
or only a small number, of side inlets;
k = 0.0004 m, for sewers with many
inlet pipes and structures (where minor
losses at joints are to be taken into
account).
Q = V F ; F = d2
4
Q = d2 V
4
1)
2)
In practice, for computational purposes,
the following semi-empirical equations
are used:
A hydraulic design concerns selecting
parameters for gravity flow sewers,
which normally do no flow full. The
objective of hydraulic design is to deter-
mine the most economic pipe diam-
eter at which the required dischargeis passed. In practice, computation of
hydraulic pipe parameters are based on
the following assumptions:
1. The assumption of a uniform flow,
meaning:
q the depth (h), flow area (f) and veloc-
ity (v) at every cross-section remain
constant at the whole considered pipe
section;q the energy grade line, water surface
and pipe bottom slope are parallel.
2. In the pipe system, the flow regime is
turbulent.
GENERAL ASSUMPTIONS2.1
HYDRAULIC DESIGN OF PRAGMA SYSTEM
GOVERNING FORMULA2.2
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HYDRAULICDESIGNOFPRAGMASYSTEM
2
HYDRAULIC DESIGN OF PRAGMA SYSTEM
NOMOGRAPH OF HYDRAULIC PARAMETERS2.3
NOMOGRAPH 1
PROPORTIONAL DEPTH RELATIONSHIPS FOR PARTLY FULL CIRCULAR PIPES
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HYDRAULIC DESIGN OF PRAGMA SYSTEM
NOMOGRAPH OF HYDRAULIC PARAMETERS2.4
NOMOGRAPH 2
DARCY-WEISBACH / COLEBROOK-WHITE FORMULA FOR GRAVITY PRAGMA PIPES
For k=0,40 mm, temp. t=1000C, full flow
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HYDRAULICDESIGNOFPRAGMASYSTEM
2
2 3 4 5 6
0,1
0,15
0,2
0,3
0,40,5
0,6
0,8
1
1,5
2
3
4568
8
10
10
10
20
20
30
30
40
40
50
50
60
60
80
80
100
100
200
150
200
300
400
500
600
800
1000
2000
3000
4000
0,30,1 0,1
50,2 0,2
5
0,4
0,5
0,6
0,8
1,0
1,5
2,0
2,5
3,0
4,0
5,0
6,0
8,0
10,0
630500
400315
250200
160
Discharge - Q[dm/s]3
nDiameter d [mm]
hydraulic
slope-i[
]
/ooo
velocity - V[m/s]
HYDRAULIC DESIGN OF PRAGMA SYSTEM
NOMOGRAPH OF HYDRAULIC PARAMETERS2.5
NOMOGRAPH 3
DARCY-WEISBACH / COLEBROOK-WHITE FORMULA FOR GRAVITY PRAGMA PIPES
For k=0,25 mm, temp. T=1000C full flow
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SLOPES AND VELOCITIES OF FLOW IN PRAGMA PIPES SLOPESThe slope of the channel must also be
considered as variable, since it is not
necessarily completely defined by topo
graphic conditions.
The minimum channel slope is required
to achieve the lowest flow velocity which
will prevent suspended solids from set-
tling out and clogging the pipe.
In general, solid particles, e.g. sand
particles, can deposit on the bottom
to a depth corresponding to the par-
ticle friction angle (see Figure 3.1),expressed as:
The area of deposition may be allowed
to a relatively flat zone of the channel
bottom.
Figure 3.1 Angle of friction
The safe lower limit of velocity to avoid
sedimentation depends on the type of
sediments. Usually, the permissible
minimum velocities (Vsc) which ensure
When determining the slope of the pipe-
line, one should select the permissible
velocities taking into account the pipe
diameter. To this end, a simple formula
can be used:
The minimum slope of the sewer pipe-
line can also be expressed by the trac-
tive force (t), given as:
The actual tractive force is:
From the above, the critical tractive
force for the actual depth of flow (hn) is:
The critical tractive force which fulfil the
condition of the channel self-cleaning
is:
Thus, from Equation 9, after rearrang-
ing, the minimum slope of the pipe is:
self-cleaning of the channel should not
be, at full flow, lower than:
Vsc = 0.8 m/s for sanitary sewers
Vsc = 0.6 m/s for storm sewers
Vsc = 1.0 m/s for combined sewers
h
n
d
()
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STRESS AND STRENGTH ANALYSIS OF BURIED PRAGMA PIPES
INTERACTION BETWEEN THE PIPE AND THE SURROUNDING SOIL
From the technical point of view, the
plastic Pragma pipe is a flexible struc-
ture having a high ability to take up
stress without failing. The classical
method to evaluate the strength of a
structural material is to describe theactual relation between the stress and
the strain when the material is loaded.
A vertical load imposed on the pipe
causes a deflection (dv), a reduction in
the vertical diameter of the flexible pipe,
which takes causes it to take an elliptical
shape (see Figure 4.1).
Figure 4.1 Deflection of circular pipe
due to vertical load
Deflection of the pipe causes bend-
ing stress in the pipe wall and exerts
pressure on the surrounding soil, and
the passive earth pressure decreases
the bending stress in the pipe wall. The
bending stress in the pipe wall caused
by deflection is in momentary balance
with the soil pressure acting against the
outside of the pipe wall. The force the of
the soil counteracting the pipe pressure
depends on the vertical load, soil type
and stiffness (density) in the pipe zone
and on the pipe stiffness.
For rigid pipes such as concrete, etc.,
the pipe alone has taken the main verti-
cal forces acting on the pipe, while flex-
ible pipe makes use of the horizontally
acting soil support exerted as a result
of the pipe deflection. Consequently,
for the flexible pipe, the integration
between the soil and the pipe has to beconsidered far more extensively than in
the case of rigid pipes.
The design concept of flexible pipes can
be explained with the classical Spangler
formula:
Equation (11) describes the relative
deflection of a pipe subjected to a verti-
cal load (qv) supported by the pipe ring
stiffness and the soil stiffness.
This equation clearly shows that pipe
deflection can be limited to the permis-
sible magnitude by increasing one or
both of the two factors, pipe ring stiff-
ness and soil stiffness in the pipe zone.
Additionally, it can be said that pipe with
greater ring stiffness is less subjected
to interaction with the soil and is less
dependent on the soil density in the
pipe zone. Whereas application of a
suitable enbedment of properly com-
pacted material (higher cost of installa-
tion) enables the use of pipes of lower
ring stiffness (lower in cost), in making a
decision both the engineering and eco-
nomic advantages of the alter-natives
must be considered.
4.1
STRESSANDSTRENGHTANALYSISOFBURIEDPRAGM
APIPES
4
Buried Pragma pipes can be calculated
with the ultimate limit state model:
q serviceability limit state can be
checked by comparison of the strain
caused by the load to the allowable
strain;
q ultimate bearing resistance state can
be checked by comparison of the
buckling stress with the compressive
stress as well as the relative strain
with the allowable strain (d).
In the following, the calculation for
flexible pipes according to the method
referred to as the Scandinavian Method
[Janson, Molin 1991] (SM) is described.
This is an analytical method based on
the soil pressure distribution in the pipe
zone shown in Figure 4.2. In it, the inter-
action between the pipe and the sur-
rounding soil is taken into account.
The maximum load which is likely to be
imposed on the pipe should be estimat-
ed ac-cording to the obligatory national
standards. The influence of a traffic load
can be cal-culated by the pressure dis-
tribution according to the Boussinesque
[PN-81/B-03020] theory.
METHOD OF CALCULATION4.2
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SYMBOLS USED IN FORMULA
qv - vertical load
qh - horizontal load
qz - load due to soil cover
qt - trafc load
qw - water pressure
gz - unit weight of the soil
gzw - water saturated unit weight ofthe soil
gw - unit weight of water
P - load of vehicle wheel
C - coefcient of trafc load
H - depth of pipe cover (from ground
level to the pipe crown)
h - height of water over the pipe
axis
D - initial undeformed diameter of
the pipe
dn - nominal inside diameter of the
pipe
r - radius of the pipe
dv - vertical deection of the pipe
SN - pipe ring stiffnessI - moment of inertia of pipes
cross wall section
E - modulus of elasticity of the pipe
- also called the creep modu-
lus which describes a creep
(increase of strain) on a con-
stantly stressed material, as well
as the relaxation modulus which
describes a relaxation (decrease)
of stress on a constantly strained
material
Es - secant modulus of the soil
Et - tangent modulus of the soil
F - safety factor against buckling,
F = 2 - strain in the pipe wall
These symbols are given without
numerical quantities, making it possible
to use the most convenient units. In the
Tables and Graphs, SI units are used.
The soil pressure distribution for theScandinavian Method [by Janson, Molin
1991] is shown in Figure 4.2. The buried
pipe is loaded with vertical load (qv),
which causes stress and strain, and with
the counteracting horizontal load (qh).
Figure 4.2 Scandinavian Model of soil
pressure distribution
VERTICAL LOADS
1. Load due to soil above the pipe:
In this case, vertical load is:
Under normal conditions of pipe installa-
tion, the vertical load (qv) component is
larger than the horizontal load (qh) com-
ponent. The difference (qv - qh) causesa reduction of the vertical pipe diameter
and an increase in the horizontal pipe
diameter. The pipe side walls, when
deforming, mobilise a passive earth
pressure of a value depending on the
imposed vertical load and on the ratio
between the soil stiffness and pipe stiff-
ness. This last is expressed as the pipe
ring stiffness (SN).
The components of load which are likely
to be imposed on a pipe in the vertical
plane are:
the effect of the soil above the pipe
the effect of loads superimposed onthe surface of the ground, such as those
from buildings, vehicle wheel loads, etc. Figure 4.3 Geometry of buried pipe
For pipes below the water table, the
total pressure shall be increased with
the hydrostatic pressure:
LOAD4.3
STRESS AND STRENGTH ANALYSIS OF BURIED PRAGMA PIPES
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STRESSANDSTRENGHTANALYSISOFBURIEDPRAGM
APIPES
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LOAD SUPERIMPOSED BY TRAFFIC
Figure 4.4 Traffic load coefficient
relationship
SERVICEABILITY LIMIT STATE
- DEFLECTION
Deflection of a buried gravity pipe
depends on the magnitude of external
loads, pipe ring stiffness, the specific
weight of the soil, type and composition
of the backfill material and the method
of installation.
A theoretical deflection caused by loads
can be calculated from the following for-
mula [by Janson, 1995]:
Figure 4.5 Minimal secant modulus
(ES) values for granular soils versus
depth of pipe cover (H) at variousdegrees of soil compaction
The secant modulus (Es) of the soil in
the pipe bedding zone depends on the
degree of soil compaction and the effec-
tive soil pressure.
Values of the secant modulus (Es) for
granular materials have been deter-
mined by laboratory tests in a hollow
cylinder apparatus (on moraine sand,
among others).
ULTIMATE LIMIT STATE MODEL4.4
STRESS AND STRENGTH ANALYSIS OF BURIED PRAGMA PIPES
4
2,0 2,5 3,0 3,5 4,0 4,5 5,0 5,5 0,0 6,5
for road I and II technical grade - A
loading grade
for road III, IV and V technical grade -
B loading grade
for higher technical class - C loadinggrade
ground water level below the pipe
5000
4000
3000
2000
1000
0
90%
85%
80%
75%
E [kN/m ]s2
consolida
tiongrad
e
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4
The initial deflection caused by
external loads for pipes bedded in
non-cohesive soils (sand, gravel) is
in the range of 2 to 4%.
The maximum initial deflection can be
estimated as follows:
The value of the installation factor (UI) is
influenced mainly by:
trench shape (see Figure 4.6); equipment and method of soil compac-
tion (see Figure 4.7);
trafc load during construction (see
Figure 4.8).
Figure 4.6 Stepped trench
Figure 4.7 Compaction with heavy
equipment (useful load > 0.6 kN)
Figure 4.8 Heavy traffic at shallow
depths
The value of the bedding factor (UB)
depends on:
unevenness in the pipe bed;
quality and quantity of construction
supervision;
skill of the installation personnel.
Figure 4.9 Bedding conditionsa) uneven pipe bedding (with large
stones)
A number of measurements on opera-
tional PP sewers show that a great part
of deflection results from the installation
method and uneven pipe bed conditions.
Therefore, installation and bedding fac-
tors should be added to the theoretical
deflection calculated in Equation 16.
STRESS AND STRENGTH ANALYSIS OF BURIED PRAGMA PIPES
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b) bedding material not placed evently
The suggested values of factors UI and
UB are given in Tables 4.1 and 4.2, pro-
vided that sand or gravel is used for the
pipe surrounding fill.
The average initial pipe deflection can
be determined by excluding the factorUB in Equation 18.
With careful execution of installation,
the mean initial value of deflection
should not exceed 5%.
The maximum initial deflection of PP
gravity sewer pipes should not exceed 9%.
It is well known that buried plastic pipes
undergo deflection in the course of
time. Final pipe deflection is a function
of changes in the soil stiffness in the
course of time due to settlement of the
trench fill and movement of soil particles
in the embedment soil.
Therefore, in order to determine the
final pipe deflection after 1 to 3 years,
one should replace Equation 16 with the
formula:
The maximum final deflection of the
PP gravity sewer pipe is given by the
formula:
The functional requirement for pipe
deflection is that pipe on a long term
basis shall be water-tight and not
essentially change its transport capac-
ity. This has led to the require-ment that
the maximum long-term deflection must
not exceed 15%.
Table 4.1 Values for the installation factor (UI)STRESSANDSTRENGHTANALYSISOFBURIEDPRAGM
APIPES
4
Figure 4.10 Bedding conditions
Table 4.2 Values for the installation factor (UB)
STRESS AND STRENGTH ANALYSIS OF BURIED PRAGMA PIPES
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External pressure causes compressive
ring forces in the pipe wall. When these
forces are large they can cause failure
due to buckling of the pipe wall.
In the circumferential direction, it is acombination of large external pressure
(or internal vacuum) and low pipe stiff-
ness that creates the risk of buckling.
In firm soil, the embedment substan-
tially increases the ability of the pipe
to resist buck-ling. In this case buckling
will occur in a small wavy pattern. How-
ever, if the surround-ing soil is weak, itscontribution to the buckling resistance is
smaller. In such conditions, the buckling
Figure 4.11 Types of Buckling
In firm soils, the permissible external
pressure due to the risk of buckling can
be calcu-lated by the following formula
(Jonson, Molin, 1991):
In cases where the pipe is surrounded
by weak soil (e.g. soft silt or clay), the
permissible pressure can be calculatedaccording to the expression which holds
for elliptical buckling, as follows:
Under the condition that:
When the pipe deflects to v/D, a strain
(and stress) is caused in a circumferen-
tial direction in the pipe wall. The magni-
tude of this strain can be expressed as:
will occur in a more or less elliptical
shape, presented in Figure 4.10. (by
Jonson, Molin, 1991).
STRESS AND STRENGTH ANALYSIS OF BURIED PRAGMA PIPES
ULTIMATE LIMIT STATE MODEL - STRAIN4.5
RELATIVE STRAIN4.6
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A bedding design depends on the soil
geotechnical characteristics of the zone
in which the sewer pipe is to be laid.
In general, two methods of pipe beddingcan be considered:
BEDDING ON NATURAL GROUNDIn some instances, it may be acceptable
to lay Pragma pipe on the bottom of
the trench, but only in granular, dry soil
which is free of large stones (> 20mm),
such as gravel, coarse sand, fine sand
and sandy clay.
In such soil conditions, the pipe is laid
on the thin (10 to 15cm), uncompactedbedding directly underneath the pipe.
The purpose of the bedding is to bring
the trench bottom up to the grade and to
provide a firm, stable and uniform invert
support of a minimum 90 angle (see
Figure 5.1). Figure 5.1 Natural bedding
BEDDING ON A FOUNDATION
There are situations where a pipeline
should be laid on a foundation. Theseinclude:
1. when in favourable natural ground
conditions, the trench is mistakenly
overcut to a depth below the designed
pipe level;
2. in rocky soils, cohesive soils (clays)
and silty soils;
3. in weak, soft soils, such as organic
silts and peat;
4. in any other conditions where the
project document requires a founda-
tion.
natural bedding on the native undis-
turbed ground;
bedding on a foundation made of
selected soil material, compacted tothe required level.
An example of the solution for cases 1
and 2 is presented in Figure 5.2. Thepipeline is laid on two layers made of
sandy soils or gravel soils with maxi-
mum size of 20mm.
The foundation layer is made of well
compacted soil of thickness 25cm
(minimum 15cm).
The bedding layer is 10 to 15cm thick,
uncompacted.
In the case of weak soils, depending
on the thickness of the weak soil layer
below the designed pipeline level, two
solutions can be applied.
1. Where the thickness of the weak soil
layer is
1.0m (see Figure 5.3).In this case, the weak soil is removed
and the trench is filled with a well-com-
pacted layer of a broken stone and
sand mixture (volume ratio 1:0.3) or a
broken stone and sand mixture (volume
ratio 1:0.6). The foundation is laid on a
geotextile.
2. Where the thickness of the weak soil
layer is > 1.0m (see Figure 5.4).
In this case, a 25cm thick foundation
made of a well-compacted layer of a
gravel and sand mixture (volume ratio 1:
3) or a broken stone and sand mixture
(volume ratio 1:0.6) laid on a geotextileis recommended.
The most important factor in achiev-
ing a satisfactory installation of flexible
conduit is the interaction between the
pipe and the surrounding soil. Most of
the pipe support is accomplished by the
soil around the lower half of the pipe
and horizontally away from the pipe in
both directions. Thus, the soil type and
degree of compaction realised in the
pipe zone are great importance. There-
fore, in any pipe installation project, the
designer must determine the conditions
for the pipe bedding, such as:
1. the ground conditions and the suit-
ability of the local soil for the pipe
bedding;2. the geotechnical characteristics for
the soil used for bedding, haunching
and initial backfill, as well as the man-
ner in which they are placed;
3. the suitable class of pipe stiffness.
To this end, the first step in any design
is a geotechnical investigation along the
entire pipe route. Routine field inves-
tigations and laboratory testing must
be carried out to provide the requiredground parameters, such as soil class
and structure, gainsize distribution,
compactability and ground water level.
EARTHWORKS
5
GENERAL CONSIDERATIONS5.1
EARTHWORKS
BEDDING CONDITIONS5.2
1- native soil2- bedding layer
90 120
2
1
0 0
d n
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Figure 5.2 Example
of a foundation in
firm soil
Figure 5.3 Foun-
dation in weak soil
of depth 1.0 m
Figure 5.4 Foundation in weak
soil of depth > 1.0 m
In all cases, the foundation layer must
be compacted to 85 to 90% of modified
Proctor test density.
Apart from a proper foundation and bed-
ding, the soil class and density realised
in the sidefill (haunching) and initial
backfill are important factors in achiev-
ing a satisfactory installation of a flexible
pipeline.
Figure 5.5 Pipeline cross-section
SIDEFILL AND INITIAL BACKFILL
The criteria to select material as suitable
to use as fill in the haunching zone (side-
fill) and directly above the crown of the
pipe (initial backfill) are based on achiev-
ing ade-quate soil strength and stiffness
after compaction. Suitable soil material
includes most graded, natural granular
materials with maximum particle size
not exceeding 10% of the nominal pipe
diameter or 60mm, whichever is smaller.
The fill material should not contain for-
eign matter such as snow, ice or frozen
earth clumps.
Table 5.1 Characteristics of sidefill and initial backfill material
SIDEFILL, INITIAL BACKFILL AND FINAL BACKFILL5.3
a)
natie soil (very weak)
solid native soil
h 1m
90 120
2
1
3
dn
0 0
c
d
ba
10 cm
e 15cm
30 30D
30 cm
B D+2 x03
1- soil fundation layer as: gravel and sand
mixture or broken stone sand mixture
2- bedding layer
3- geotextile
a- main backfill
b- cover depth
c- pipe zone
d- bedding if requirede- fundotion if required
EARTHWORKS
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EARTHWORKS
5
DEGREE OF COMPACTION
The required degree of fill compaction
depends on loading conditions.
In paved areas, the minimum soil
compaction in the pipe zone is 90% of
modied Proctor test density.
Outside of paved areas, the ll should
be compacted to:
- 85% of modied Proctor test density if
the depth of cover is < 4.0 m;
- 90% of modied Proctor test density if
the depth of cover is 4.0 m.
The fill material should be compacted to
layers of 10 to 30 cm in thickness.
The thickness of the initial backfill over
the crown of the pipe should be:
minimum 15 cm for a pipe of diameter
D < 400 mm;
minimum 30 cm for a pipe of diameter
D 400 mm.
FINAL BACKFILL
The material used for completing the
backfilling can be made with exca-
vated material if suitable to achieve the
required project compaction and can
have maximum particle size of 300 mm.
For pipelines of diameter D < 400 mm
and with an initial backfill thickness of 15
cm, the final backfill material should not
contain particles of size > 60 mm.
In paved areas, the minimum compac-
tion of the final backfill should be 90% of
modified Proctor test density.
TAMPING THE EMBEDMENT
MATERIAL
The requirements for the degree of
compaction depend on the load condi-
tions and should be given in the project
document. Tamping can be done with
different tamping equipment. Depend-
ing upon the equipment, thickness of
layers and soil compactability, different
degrees of compaction can be achieved.
In Table 5.2, some data is given which is
valid for gravel and sandy soils.
Table 5.2 Compaction methods
TRENCH WIDTH
The width of the trench should enable
the proper placement and compaction
of the fill material. The minimum width
of the sidefill is bmin = 30 cm. Thus, the
minimum width of the trench (B) at the
top of the pipe is: bmin)
dn
If the stiffness of the native undisturbed
ground is lower than the stiffness of the
designed fill, the trench width (B) should
be:
(in general, this condition deals with
pipes in diameter dn > 250 mm because
for pipes of smaller diameter the trench
width (B) fills this condition)
Such situations can take place in granu-
lar soils of low density (ID < 0.33) or in
cohesive soils of plastic limit IL > 0.0.
EARTHWORKS
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CUTTING PIPE - MOUNTING SEALING RING6.2
CONNECTION OF PRAGMA PIPE (SPIGOT) WITH PVC PIPE6.3
1) To clean the socket, seal and thespigot of the pipe. 2) To lubricate the seal. 3) To push a spigot into a socket.
Cut pipe in a corrugation valley, using a
fine tooth carpenters saw. Mount seal-
ing ring in first corrugation valley.
1) To examine and clean a socket, seal-ing ring and Pragma spigot.
2) To lubricate a seal in a socket. To
push a coupler into a socket.
CONNECTION OF PRAGMA-PRAGMA PIPES6.1
INSTALLATION OF PRAGMA PIPES
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6
INSTALLATIONOFPRAGMAPIPES
1) To make a whole in a concrete cham-
ver.
2) To fix a Pragma adapter. 3) To connect pipe to the adapter.
CONNECTION OF PRAGMA TO CONCRETE CHAMBER(SOCKET)6.5
1) To put the seal into the inside groove
of a socket on the edge of the socket
to install click-ring.2) To drive the click (using rubber ham-
mer).
3) To lubricant a seal.
4) To push a spigot into a socket.
CONNECTION OF PRAGMA PIPE (SOCKET) WITH SMOOTHPVC PIPE (SPIGOT)
6.4
INSTALLATION OF PRAGMA PIPES
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PRODUCT RANGEPIPES
FITTINGS
Pragma double walled sewer pipe
PPPragma bend
SEWER PIPESAND FITTINGSOF Pragma SYSTEM
PRODUCT RANGE
d
[mm]
L
[m]
t
[mm]160
200
250
315
400
500
630
160
200
250
315
400
500
630
6,0
6,0
6,0
6,0
6,0
6,0
6,0
3,0
3,0
3,0
3,0
3,0
3,0
3,0
94
113
129
148
158
188
232
94
113
129
148
158
188
232
dn
Lt
n
d[mm]
Z[mm]
Z[mm]
[ ]t
[mm]A
[mm]
160
160
160
200
200
200
200
250
250250
250
315
315
315
315
400
400
400
400
500
500
500
500630
630
630
630
110
121
149
134
159
158
442
186
203287
459
197
218
320
533
222
250
366
615
241
275
399
679285
328
477
818
15
30
45
15
30
45
90
15
3045
90
15
30
45
90
15
30
45
90
15
30
45
9015
30
45
90
21
31
41
23
176
48
459
161
178261
434
169
217
320
533
220
248
363
613
238
272
396
679284
327
476
817
97
97
97
116
113
116
113
129
129129
129
148
148
148
148
158
158
158
158
188
188
188
188232
232
232
232
110
108
116
119
132
119
132
170
170170
170
176
176
176
176
196
196
196
196
208
208
208
208244
244
244
244
AZ
Z
1
2
tdn
n 1 2
PP Pragma concrete chamber adapter
d[mm]
n
d
A
n A[mm]
160
200
250
80
80
80
315400 8080
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PRODUCTRANGE
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7. LITERATURE
BN-83/883-02 Przewody podziemne. Roboty ziemne. Wymagania i badania przy odbiorze.
BN-67/8936-01 Drogi samochodowe. Odprowadzanie wd opadowych z drogi. Wskaniki techniczne wykonania i odbioru.
BN-72/8932-01 Budowle drogowe i kolejowe. Roboty ziemne.
BN-91/8836-06 Roboty podziemne. Roboty ziemne. Wymagania i badania przy odbiorze.
Geotextiles and geotextile - related produucts - classifications scheme (draft). Document No. 95/BSI STANDARDS, November
1995
ISO-4422-2. Pipes and fittings made of unplasticized poly(vinyl chloride) (PVS-U) for water supply - specifications
Technische Lieferbedingungen fur Geotextilen und Geogitter fur den Erdbau im trassenbau TL Geotex E-StB 95-1995
European standard. Preliminary draft. EN(155WJO19). Plastic piping system for water supply - PVC-U. February 1992.
ISO/TC 138/SC 2. Draft technical report. Polyethylene (PE, pipes for conveyance of water under pressure. Recommended
practice for laying. 1985.
Bolt A.: Programowanie bada geotechnicznych dla celw posadowienia sieci wodnokanalizacyjnych z tworzyw sztucznych.
Inynieria Morska i Geotechnika Nr 4, 1997
Bolt A.F.:, Duszyska A.: Kryteria doboru geosyntetykw jako warstw separacyjncyh i filtracyjnych. Inynieria Morska i Geo-
technika, Nr 1, 1998
Janson L.E., Molin J.: 1991, Design and installation of buried plastic pipes. Stockholm, Akaprint ApS, Aarhus
Janson L.E.: Plastic Pipes for Water Supply and Sewage Disposal, Stockholm, 1995
Polyethylene Pipe System Handbook, Mabo AS. Oslo, Norway.
Polyethylene pipe systems for water supply. Manual, WRC Swindon 1994.
PVC Pressure pipe systems. Manual. WRC Swindon, 1994
Tullis J.P.: 1989; Hydraulics of Pipelines. John Wiley & Sons, New York, USA LITERATURE
7