Stv cc ppt unit i (1.1)em&ce introduction-construction layout

stv cc ppt unit I (1.1) em&ce- introduction-construction layout

Unit I (1.1)
Earth moving and construction equipments-introductionconstruction layout

BAM 802 SPECIAL TYPE OF VEHICLES
2013-2014
- C.COOMARASAMY- PROF/AUTO- BIST

1.1.0. EARTH MOVING & CONSTRUCTION EQUIPMENT
Introduction:
1. The Earthmoving Process
2. Equipment Selection
3. Production of Earthmoving Equipment
1. Earth moving Process:
 Earthmoving is the
Earthworks, in their simplest
process of moving
form, involve processes such as
soil or rock from
excavating, hauling, dumping, crushi
one location to another and
ng and compacting (Ricketts, Loftin and
processing it so that it meets Merritt 2003).
construction requirements of An earthmoving operation consists of
the preparation of material,
location,
the loader/truck loading cycle,
haulage of trucks to the disposal
elevation,
place, the deposition of the material
- density, trucks’ return trip to the loading
and the
station to start another load-and-haul
- moisture content,

1.1.0. EARTH MOVING & CONSTRUCTION EQUIPMENT
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The most common method in earthmoving is
to employ a number of excavators, wheel loaders and haulers to
prepare, excavate, load and transport soil.
This method is more beneficial when the
hauling distances and material quantities involved are
relatively large.
The second method is to use more independent equipment such as
scrapers and wheel loaders to
carry out the entire process, and this method is
more appropriate when
the transport distance is short.
Depending on the scope and working condition of each
project, different operation methods and machine types should be
selected to maximize the overall performance of the operation.

1.1.1. EARTH MOVING PROCESS
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may include
site preparation;
excavation;

Site preparation involves preparing of flat ground level for the excavator and
hauling unit for operation. This can usually be done by the excavator at the
operation site. But for covering the lead distance and other access roads, it is
necessary to have road-building units like dozers and motor graders.

loading, hauling,
embankment,
construction;

site preparation
excavation

excavation
loading

loading

excavation

construction
loading

hauling

embankment

dredging
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dredging;

This involves removal of sand/soil from
water bodies like the back water in
shallow ports, rivers & lakes.
This can be accomplished by using
clam-shells, draglines or de-weeding buckets.
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dredging
dredging

backfilling;
placing (dumping and spreading),

backfilling
dumping

spreading

trenching

•preparing base course,
•sub base, and sub grade;
•compaction;
•and surfacing.
(finishing)

Sub grade elevation

Compaction-rollers

Checking sub grade density

compaction

Finished surface
Compaction and grading


Sub Base preparation

Efficient management of the earthmoving process requires :
(i) accurate estimating of work quantities and job conditions,
(ii) proper selection of equipment, and
(iii) competent job management.

1.1.2.EQUIPMENT SELECTION
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The types of equipment used and the
environmental conditions will affect the
man- and machine-hours required to Earthwork operations are
complete a given amount of work. highly equipment-driven
processes and the
Before preparing estimates,
equipment costs constitute a
choose the best method of
major part of the investment
operation and the
and operating cost.
type of equipment to use.
In general, the most
frequently employed
Each piece of equipment is
equipment for earthworks are
specifically designed to perform
dozers,
certain mechanical tasks.
scrapers,
Therefore, base the
wheel loaders,
equipment selection on
excavators,
haul trucks and
efficient operation and
compactors.
availability.

1.1.2.EQUIPMENT SELECTION

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The choice of equipment to be used on
a construction project has a major Influence on the
efficiency and profitability of the
construction operation.
Although there are a
number of factors that should be
considered in
selecting equipment for a project, the
most important criterion is the
ability of the
equipment to
perform the required work.

1.1.2. EQUIPMENT SELECTION
Among those items of equipment capable of performing the job, the
principal criterion for selection should be
 maximizing the profit or return on the
 investment produced by the equipment.
 Usually, but not always, profit is maximized when the
 lowest cost per Unit of production is achieved.
Other factors that should be considered when selecting equipment for a
project include:
 possible future use of the equipment,
 its availability,
 the availability of parts and service, and
 the effect of equipment downtime on
 other construction equipment and operations.
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1.1.2. EQUIPMENT SELECTION

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After the equipment has been
selected for a project,
a plan must be
developed for
efficient utilization of the equipment.
The final phase of the
process is, of
course,
tent job management to assure
compliance with the
operating plan and to make
adjustments for
unexpected conditions.

1. Equipment selection

2. A plan development

compe
3. Job management

A Gladiator Tactical

1.1.2.1. GROUND VEHICLES- INTRODUCTION
Ground vehicles are those vehicles that are
Unmanned ground vehicle
supported by the ground, in contrast with
aircraft and marine craft, which in operation are
supported by air and water, respectively.
Ground vehicles may be broadly classified as
guided and
non guided.
Guided ground vehicles are constrained to
move along a
fixed path (guide way), such as
railway vehicles and tracked levitated vehicles.

Railway vehicles

A magnetically levitated (maglev) train

Non guided ground vehicles can move,
by choice,
in various directions on the ground, such as
road and off-road vehicles.
The mechanics of non guided ground vehicles is the subject we
discuss.
The prime objective of the study of the
mechanics of ground vehicles is to
establish guiding principles for the
rational development,
design, and
selection of
vehicles to meet
various operational requirements.
Willys CJ (later Jeep CJ) (or "Civilian Jeep")

In general, the
Characteristics of a ground vehicle may be described in terms of its
(a) performance,
(b) handling, and
( c) ride.
(a) Performance characteristics refer to the
ability of the vehicle to accelerate,
to develop drawbar pull,
to overcome obstacles, and
to decelerate.
(b) Handling qualities are concerned with the
response of the vehicle to the
driver's commands and
its ability
to stabilize its motion against
external disturbances.

( c) Ride characteristics are related to the
vibration of the vehicle excited by
surface irregularities and
its effects on passengers and goods.
The theory of ground vehicles is concerned with the
study of the performance, handling, and ride and their
relationships with the
design of ground vehicles under
various operating conditions.
The behavior of a ground vehicle represents the
results of the interactions among
the driver,
the vehicle, and
the environment, as illustrated in Fig. 1.

1.1.2.2. THE DRIVER-VEHICLE-GROUND SYSTEM
VISUAL AND
OTHER INPUTS

GROUND CONDITIONS
ACCELERATOR
BRAKES

PERFORMANCE

DRIVER
STEERING
SYSTEM

VEHICLE

SURFACE
IREGULARITIES
AERODYNAMIC INPUTS

HANDLING

RIDE
Fig. 1.

An understanding of the behaviour of the human driver,
the characteristics of the vehicle, and the physical and geometric properties of the ground
is, therefore, essential to the design and evaluation of ground vehicle systems.

1.1.2. 3. MECHANICS OF PNEUMATIC TIRES
Aside from aerodynamic and gravitational forces,
all other major forces and moments affecting the
motion of a ground vehicle are applied through the
running gear-ground contact.
An understanding of the basic characteristics of the interaction between
the running gear and the ground is, therefore, essential to the
study of (a) performance characteristics,
(b) handling behavior of ground vehicles, and
( c) ride quality.
The running gear of a ground vehicle is generally required to fulfill the
following functions:
 (i) to support the weight of the vehicle
 (ii) to cushion the vehicle over surface irregularities
 (iii) to provide sufficient traction for driving and braking
 (iv) to provide adequate steering control and direction stability.

1.1.2.3. MECHANICS OF PNEUMATIC TIRES
Pneumatic tires can perform these functions effectively and efficiently;
thus, they are
universally used in road vehicles, and are also
widely used in off-road vehicles.
The study of the mechanics of pneumatic tires therefore is
of fundamental importance to the understanding of the
performance and
characteristics of ground vehicles.
Two basic types of problem in the mechanics of tires are of special
interest to vehicle engineers.
1. One is the mechanics of tires on hard surfaces, which is essential to
the study of the characteristics of road vehicles.
2. The other is the mechanics of tires on
deformable surfaces (unprepared terrain), which is of
prime importance to the study of
off-road vehicle performance.

1.1.2.4. TIRE FORCES AND MOMENTS
To describe the characteristics of a tire and
the forces and moments acting on it,
it is necessary to define an axis system that serves as a reference for
the definition of various parameters.
One of the commonly used axis systems recommended by the
Society of Automotive Engineers is shown in Fig. 1.2
The origin of the axis system is the center of tire contact.
The X axis is the intersection of the
wheel plane and the ground plane with a positive direction forward.
The Z axis is perpendicular to the
ground plane with a positive direction downward.
The Y axis is in the ground plane, and its direction is chosen to make the
axis system orthogonal and right hand.

perpendicular to the ground plane

+ direction downward.

+ direction forward

center of tire contact.

1.1.2.4. TIRE FORCES AND MOMENTS chosen
direction
orthogonal and right hand

1.1.2.4. TIRE FORCES AND MOMENTS
There are three forces and three moments acting on the tire from the
ground.
Tractive force (or longitudinal force) Fx, is the component in
the X direction of the resultant force exerted on the tire by the road.
Lateral force Fy, is the component in the Y direction, and
normal force Fz, is the component in the Z direction.
Overturning moment Mx, is the moment about the X axis exerted on the
tire by the road.
Rolling resistance moment My is the moment about the Y axis, and
aligning torque Mz, is the moment about the Z axis.
With this axis system, many performance parameters of the tire can be
conveniently defined.

1.1.2.5. MECHANICS OF VEHICLETERRAIN INTERACTION -TERRAMECHANICS

While transporting passengers and goods by
vehicles on paved roads constitutes a
significant part of the
overall transportation activities in a modern
society,
a w i d e range of human endeavors in such
fields as
agriculture, logging, construction, mining, exploration, recreatio
n, and military operations still involves locomotion over
unprepared terrain using specialized off-road vehicles.
Systematic studies of the principles underlying the
rational development and design of off-road
vehicles,
therefore, have attracted considerable
interest, particularly since World War II.
The study of the performance of an off-road vehicle in relation to
its operating environment (the terrain) has now become known as
"terramechanics“


In off-road
operations,
various types of terrain with differing behavior,
ranging from desert sand through
soft mud to fresh snow, may be encountered.
The properties of the terrain quite often
impose severe limitations to the mobility of off-road vehicles.
An adequate knowledge of the mechanical properties of the
terrain and its response to vehicular loading-terra mechanics
is, therefore, essential to the proper development and design of
off-road vehicles for a given mission and environment.
This is, perhaps, analogous to the role of
aerodynamics in the development of
aircraft and spacecraft and to that of
hydrodynamics in the design of
marine craft.


On a given terrain, the
performance of an off-road vehicle is, to a great
extent, dependent upon the manner in which the
vehicle interacts with the terrain.
Consequently, an understanding of the
mechanics of vehicle-terrain interaction is of importance to the
proper selection of vehicle configuration and design parameters
to meet specific operational requirements.
A central issue in terra mechanics is to establish a quantitative
relationship between the performance and design of an
off-road vehicle for a given operating environment.
Over the years, a variety of methods, ranging from empirical to
theoretical, for
predicting the performance of tracked and wheeled vehicles
over unprepared terrain have been developed or proposed.

1.1.2.6. SELECTION OF VEHICLE CONFIGURATIONS
FOR OFF-ROAD OPERATIONS
Depending on the construction application,
heavy machinery will be used in different ways.
Heavy equipment could be divided in four major components:
 1. Earthmoving equipment
 2. Construction vehicles
 3. Material handling
 4. Construction Equipment
Wheel loaders


Vehicle configuration can generally be defined in terms of
form,
size,
weight, and power .
Selection of vehicle configuration is primarily based on
mission and operational requirements and on the
environment in which the vehicle is expected to operate.
In addition,
fuel economy,
safety,
cost,
impact on the environment,
reliability,
maintainability, and other factors have to be taken into
consideration.


To define an
optimum vehicle configuration for a given
mission and
environment,
a systems analysis approach should therefore
be adopted.
The analysis of terrain-vehicle systems usually
begins with defining
mission requirements, such as the
type of work to be performed,
the kind of payload to be transported, and the
operational characteristics of the vehicle system, including
output rates,
cost, and
economy.


The physical and geometric properties of the
terrain over which the vehicle is expected to
operate are collected as inputs.
Competitive vehicle concepts with
probability of accomplishing the specified mission requirements
are chosen, based on
past experience and
future development trends.
The operational characteristics and
performance of the vehicle candidates are then
analyzed and compared.
In the evaluations, employ relevant methods and techniques.
As a result of systems
analysis,
an order of merit for the vehicle candidates is
established, from which an optimum vehicle configuration is
selected.


Thus, selection of vehicle configuration for a given mission and
environment is a complex process, and it is not possible to
define the optimum configuration without detailed analysis.
However, based on the
current state of the art of off-road transport
technology,
some generalization of the
merits and
limitations of
existing vehicle configurations may be made.
Broadly speaking, there are currently
four basic types of ground vehicle capable of operating over a
specific range of unprepared terrain:
 wheeled vehicles,
 tracked vehicles,
 air cushion vehicles, and
 hybrid vehicles.


Wheeled Vehicles :
Referring to the analysis of the tractive performance of off-road vehicles
the maximum drawbar-pull-to-weight ratio of a vehicle may be
expressed by
F d / W = ( F - ∑ R ) / W = ( c A + W tan ф - fr W ) / W
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= c / p + tan ф - f r
This equation indicates that for a given terrain with specific values of
cohesion and angle of internal shearing resistance, c and ф the
maximum drawbar-pull-to-weight ratio is a function of the
contact pressure p and the coefficient of motion resistance f r .
The lower the contact pressure and the coefficient of motion
resistance, the higher is the maximum drawbar-pull-to weight ratio.
Since the contact pressure and the motion resistance are
dependent on the design of the vehicle, the proper selection of
vehicle configuration is of utmost importance.

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For given overall dimensions and gross weight,
a tracked vehicle will have a larger contact area than
a wheeled vehicle.
Consequently, the ground contact pressure, and hence the sinkage
and external motion resistance of the tracked vehicle, would
generally be lower than that of an equivalent wheeled vehicle.
Furthermore, a tracked vehicle has a longer contact length than a
wheeled vehicle of the same overall dimensions.
Thus, the slip of a tracked vehicle is usually lower than that of an
equivalent wheeled vehicle for the same thrust.
As a result, the mobility of the tracked vehicle is generally
superior to that of the wheeled vehicle in difficult terrain.
The wheeled vehicle is, however, a more suitable choice than the
tracked one when frequent on-road travel and high road speeds are
required.

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Tracked Vehicles :
Although the tracked vehicle has the capability of operating over
a wide range of unprepared terrain, to
fully realize its potential, careful attention must be given to the
design of the track system.
The nominal ground pressure of the tracked vehicle
(i.e., ratio of the vehicle gross weight to the nominal ground
contact area) has been quite widely used in the past as
a design parameter of relevance to soft ground performance.
However, the shortcomings in its general use are now evident, both
in its neglect of the actual pressure variation under the track and in
its inability to distinguish between track designs giving different
soft ground mobility. It has been shown that the vehicle sinkage, and
hence motion resistance, depend on the
maximum pressure exerted by the vehicle on the ground and
not the nominal pressure.


Therefore, it is of prime importance that the

design of the track system should give as
uniform a contact pressure on the ground as possible
under normal operating conditions.
For low-speed tracked vehicles,
fairly uniform ground contact pressure could be achieved by
using a
relatively rigid track with a long track pitch and
a large number of small diameter road wheels.
 For high-speed tracked vehicles,
to minimize the vibration of the vehicle and of the track,
relatively large diameter road wheels with considerable
suspension travel
and short track pitch are required.
 This would result in a rather
non uniform pressure distribution under the track.
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The overlapping road wheel arrangement provides
a possible compromise in meeting the
conflicting requirements for soft ground mobility and
high-speed operations.
Pneumatic tracks and
pneumatic cushion devices have also been proposed
to provide a more uniform pressure distribution on the ground.
Experience and analysis have shown that the
method of steering is also of
importance to the mobility of tracked vehicles in difficult terrain.
Articulated steering provides the vehicle with
better mobility and
maneuverability than
skid-steering over
soft terrain.


Articulated steering also makes it possible for
the vehicle to achieve a more rational form since a long, narrow
vehicle
encounters less external resistance over soft ground than does a
short, wide
vehicle with the same contact area.
From an environmental point of view,
 articulated steering causes less damage to the terrain during
maneuvering than slud-steering.
 The characteristics of the transmission also play
a significant role
in vehicle mobility over soft ground.
Generally speaking, automatic transmission is preferred as
it allows gear changing without interruption of
power flow to the running gear.

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Air-Cushion Vehicles :
A vehicle wholly supported by an air cushion and
propelled by a propeller or fan air can operate over
level terrain of
low bearing capacity at
relatively high speeds.
It has, however, very limited capabilities in
slope
climbing,
traversing, and
crossing.
Its maneuverability in confined space is
generally poor without a ground contact device.
Existing air propulsion devices are
relatively inefficient, and
could not generate sufficient thrust at low speeds.

slope
obstacle

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Over rugged
terrain,
skirt
damage could pose
a serious problem,
while over snow or sandy
terrain,
visibility
could be considerably
reduced by a cloud of small particles formed around the vehicle.
With the current state of the
art,
the
potential of the air-cushion vehicle with
air propulsion can only be fully exploited over
relatively flat and smooth terrain
at high speeds.

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Hybrid Vehicles :
Hybrid vehicles are those that employ
two or more forms of running gear, such as the
half-tracked vehicle with front wheel steering,
the air-cushion assist-wheeled vehicle, and
the air-cushioned assist-tracked vehicle.
The tractive performance of a half-tracked vehicle can be predicted
using a combination of the methods developed for
wheeled and tracked vehicles.
It can be said, however, that the use of the
wheel as a directional control device for the
air-cushion vehicle in
overland operations is however, the use of the
wheel as a traction device over difficult terrain has
severe limitations, as mentioned previously.

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Over exceedingly soft and cohesive terrain, such as deep mud or
semi liquid swamp, the air-cushion assist-tracked vehicle may have
certain advantages from a technical standpoint.
This is because over this type of terrain, the air cushion can be used to
carry a high proportion of the vehicle weight, thus
minimizing the sinkage and motion resistance of the vehicle.
The track could then be used solely as a propulsion device.
Since in a cohesive type of terrain, the thrust is mainly a function of
the track contact area and the cohesion of the terrain, and is more or
less independent of the normal load, a track with suitable dimensions
may provide the vehicle with the necessary thrust and mobility.
However, the added weight, size, and cost of the aircushion-assist
device must be carefully evaluated against the benefits obtainable,
and the decision on the development of this hybrid vehicle
configuration should be based on the results of a
comprehensive cost-effectiveness analysis.

1.1.3. PRODUCTION OF EARTHMOVING EQUIPMENT
The basic relationship for estimating the production of
all earthmoving equipment is:
Production = Volume per cycle

Cycles per hour

The term "volume per cycle" should represent the
average volume of material moved per equipment cycle.


Thus the nominal capacity of the excavator or haul unit must
be modified by an appropriate fill factor based on the type of
material and equipment involved.



The term "cycles per hour" must include any
appropriate efficiency factors, so that it represents
the number of cycles actually achieved (or expected to be
achieved) per hour.
In addition to this basic production relationship, there are
specific procedures for estimating the production of
major types of
earthmoving equipment .



The cost per unit of production may be calculated as follows:
Cost per unit of production
= Equipment cost per hour Equipment production per hour.


There are two principal approaches to
estimating job efficiency in
determining the number of cycles per hour to be used.
 One method is to use the
number of effective working minutes per hour to calculate the
number of cycles achieved per hour.
 This is equivalent to using an efficiency factor equal to the
number of working minutes per hour divided by 60.



The other approach is to
multiply the
number of theoretical cycles per 60-min hour by
a numerical efficiency factor.
 A table of efficiency factors based on a
combination of job conditions and
management conditions is
presented in Table2-1.

1.1.4. EARTHWORK CONSTRUCTION AND LAYOUT
Earthwork construction and layout : site layout and control : Elevations – The basics
1.Elevation are all relative to known benchmarks.
2.So from below, the bench mark is known to be at 100 m
3.When surveyed the pole reading at the benchmark is 2 m Survey pole
4.So the elevation line of sight is 100 m + 2 m = 102 m
Pole reading = 2 m

Bench Mark =100 m

5. Now obtain the new reading at point A below, the pole reading = 3.9 m
Survey pole

Pole reading = 3.9 m

So the elevation at PT. A = Line of sight elevation – Pole reading at PT. A
= 102 .0 m – 3.9 m = 98.1 m


Differential Leveling: A surveying process in which a horizontal line of
sight of known elevation is intercepted by a graduated standard, or rod, held
vertically on the point being checked.
Key Terms:
 Bench Mark
(BM) = A permanent point of known elevation.
 Temporary Bench Mark (TBM) = A point of known elevation.
 Turning Point
(TP) = An intervening point between BMs or TBMs
upon which a back sight and a foresight are taken.
 Back sight
(BS) = A rod reading taken by "looking back" at a point
of known elevation such as a BM or TP.
 Foresight
(FS) = A rod reading taken when "looking ahead" at a
point where you want to determine its elevation, such as a TP, TBM or BM.
 Height of Instrument
(HI) = The elevation of the line of sight in the
telescope of the level.
Key Equations:
 Height of Instrument
(HI) = Known elevation + Backsight (BS)
 Turning Point
(TP) = Height of Instruction (HI) – Foresight (FS)


Trigonometric Leveling:
When you know the vertical angle and either the horizontal or
slope distance between two points, you can apply the fundamentals of
trigonometry to calculate the difference in elevation between the
points. This method of indirect leveling is particularly adaptable to
rough, uneven terrain where direct leveling methods are
impracticable or too time consuming
 Key Equations:
 V = S sin α
 HI = distance from AO
 R= distance from BC



Elevation at B = elevation at A +HI + V - R

1.1.5. ESTIMATING EARTHWORK
Types of excavations
 1. Small pit
 2. Trench
 3. Large areas
Roadways
 Find cut and fill using
cross sections
 Mass diagram
1. Pit Excavations
 Area X average depth
 Depending on size and
 ground may break into
 several geometric shapes to get
 volume
 Give bank volume

1.1.5. ESTIMATING EARTHWORK

2. Trench Excavations
 V = cross sectional area X length
 Take cross sections every 15m and compute volumes between x
sections
3. Large Areas
 Use a grid to find volume
To estimate the volume,
use the area that has been
determined (as width and height) and
then multiply by the distance
between each section (depth).
Note that the first and last section is
on the site boundary.

1.1.6. ROAD CONSTRUCTION TECHNIQUES
FAO-Watershed management field manual. Construction Staking

Construction grade check.
Engineer stands on center of
construction grade and sights to RP tag.
Measured distance and slope allow for
determination of additional cut.

Road cross section showing possible
construction information


Clearing and Grubbing of the Road
Construction Area

Three basic road prism construction methods.

Bulldozer in Road Construction
 Probably the most common piece of equipment
in forest road construction is
the bulldozer equipped with straight or U-type blades.
 These are probably the most economical pieces of equipment when
material has to be moved a short distance.
 The economic haul or push distance for a
bulldozer with
a straight blade is from 17 to 90 meters depending on grade.
 The road design should attempt
to keep the mass balance points within these constraints.

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The road design should consider the following points when
bulldozers are to be
used for road construction.
1. Roads should be full benched.
Earth is side cast and then wasted
rather than used to build up side cast fills.
2. Earth is moved down-grade with the aid of gravity, not up-grade.
3. Fill material is borrowed rather than
pushed or hauled farther than the
economic limit of the bulldozer.
4. Rock outcrops should be bypassed.
Unless substantial rock blasting is specified requiring
drilling and blasting equipment,
solid rock faces should be avoided.
(This, however, is primarily a road locator's responsibility.)

Road construction with a bulldozer.
The machine starts at the top and in
successive passes excavates down to
the required grade.
Excavated material is side cast and may
form part of the roadway.

Fill Construction


Fills which are part of the roadway
should not be constructed
by end dumping.

Sub grade Construction with Excavator
First pass with excavator, clearing logs
and stumps from construction site.
Working platform or pioneer road just
outside of planned road surface width

Second pass with excavator, removing or
stripping overburden or unsuitable
material and placing it below pioneer road.

Third pass, finishing sub grade and
embankment fill over pioneer road.
Road side ditch is finished at the same time.

1.1.6. REFERENCES
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Abrosmov.K.et.al., Road making machinery.
Wong. J.T., Theory of Ground vehicles.
JIALI FU., Logistics of Earthmoving Operations
CTC-375 Construction Methods
FAO-Watershed management field manual.
Ppt Materials handling by Rohit Verma.
L&T Equipments.

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Stv cc ppt unit i (1.1)em&ce introduction-construction layout

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