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

BAM 802 SPECIAL TYPE OF VEHICLES2013-2014- C.COOMARASAMY- PROF/AUTO- BIST

Unit I (1.1)

Earth moving and construction equipments-introduction-construction layout

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

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

process of moving

soil or rock from

one location to another and processing it so that it meets construction requirements of

- location, - elevation, - density,

- moisture content,

- and so on.

Earthworks, in their simplest form, involve processes such as excavating, hauling, dumping, crushing and compacting (Ricketts, Loftin and Merritt 2003). An earthmoving operation consists of the preparation of material,the loader/truck loading cycle,haulage of trucks to the disposal place, the deposition of the material and the trucks’ return trip to the loading station to start another load-and-haul cycle.

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.

1.1.0. EARTH MOVING & CONSTRUCTION EQUIPMENT

1.1.1. EARTH MOVING PROCESS

- may include

excavation

embankment

excavationloading

loading hauling

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.

construction

site preparation

loadingloading

loading

loading

site preparation;excavation;

loading, hauling,embankment, construction;

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http://en.wikipedia.org/wiki/File:Wheel-loader02.jpg

http://en.wikipedia.org/wiki/File:Wheel-loader02.jpg

dredging;

backfilling; placing (dumping and spreading),


dredging

dredging

dredging

backfilling

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.

spreading trenching

dumping


Sub grade elevation

Checking sub grade density

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

compactionCompaction and grading

Compaction-rollers

Finished surface

http://en.wikipedia.org/wiki/File:Landfill_compactor.jpg

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

The types of equipment used and the

environmental conditions will affect the

man- and machine-hours required to

complete a given amount of work. Before preparing estimates,

choose the best method of

operation and the

type of equipment to use. Each piece of equipment is

specifically designed to perform

certain mechanical tasks. Therefore, base the

equipment selection on

efficient operation and

availability.

Earthwork operations are highly equipment-driven processes and the equipment costs constitute a major part of the investment and operating cost. In general, the most frequently employed equipment for earthworks are dozers,scrapers,wheel loaders, excavators, haul trucks and compactors.

1.1.2.EQUIPMENT SELECTION

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.

1.1.2. EQUIPMENT SELECTION

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, competent job management to assure compliance with the

operating plan and to make adjustments for

unexpected conditions.

1. Equipment selection

2. A plan development

3. Job management

1.1.2.1. GROUND VEHICLES- INTRODUCTION

Ground vehicles are those vehicles that are 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.

A magnetically levitated (maglev) train Railway vehicles

Unmanned ground vehicle

A Gladiator Tactical

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

GROUND CONDITIONS

PERFORMANCE

VEHICLE HANDLING

RIDE

VISUAL ANDOTHER INPUTS

ACCELERATORBRAKES

STEERING SYSTEM

SURFACEIREGULARITIES

AERODYNAMIC INPUTS

DRIVER

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.

Fig. 1.

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.

center of tire contact.inte

rsecti

on of the w

heel plane and th

e ground plane

perp

en

dic

ula

r to

th

e g

rou

nd

pla

ne

ground plane

+ direction forward

+ direction downward.

direction chosenorthogonal and right hand



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 VEHICLE-TERRAIN 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, recreation, 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.


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

1.1.2.6. SELECTION OF VEHICLE CONFIGURATIONS FOR OFF-ROAD OPERATIONS

Wheel loaders

Civil construction equipments

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

= 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.


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.


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.


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.


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, slope traversing, and obstacle 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.

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.



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.


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.

Survey pole

Pole reading = 2 m

Bench Mark =100 m

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 4.So the elevation line of sight is 100 m + 2 m = 102 m

Survey pole

Pole reading = 3.9 m

5. Now obtain the new reading at point A below, the 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

1.1.4. EARTHWORK CONSTRUCTION AND LAYOUT

Earthwork construction and layout : site layout and control : Elevations – The basics

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)


Earthwork construction and layout : site layout and control : Elevations – The basics

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

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

1.1.5. ESTIMATING EARTHWORK

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

Road cross section showing possible construction information

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.

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.


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.


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.

Sub grade Construction with Excavator


1.1.6. REFERENCES

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. www.learncivilengineering.com Google web & images.

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

Education

types of equipment

type of equipment

equipment costs

independent equipment

piece of equipment

choice of equipment

equipment selection2

proper selection of