Chapter 1 remade luong duc long

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Last week we studied about several characteristics of Vietnamese construction industry and about the construction process We have known that there is a tight relationship between the construction industry and the national economy The construction industry is one of the most important and largest industries We learnt about types

of contractors and five approaches by which facilities are constructed.

The next chapter “introduction to earthwork”

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Earthmoving Materials and Operations

• 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, and so on.

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Number of factors for selecting equipments

• The most important criterion is the ability of equipment to perform the required work

• The principal criterion for selection should be maximizing the profit or return on the investment produced by the

equipment (usually, when the lowest cost per unit is

achieved).

• Others:

- Possible future use

- Its availability

- The availability of part and service

- The effect of equipment downtime on other construction

Planning and controlling for

equipment usage

• After the equipment has been selected for a project, a plan (such as assignment for

equipment, schedule of usage, plan for

maintenance, risk plan…) must be developed

to efficiently utilize the equipment.

• The final phase of the process is competent

job management to assure compliance with the operating plan and to make adjustments for unexpected conditions

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• The basic relationship for estimating of all

earthmoving equipment is:

Production= Volume per cycle * Cycles per hour (*)

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• The term “volume per cycle”= 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 “cycle per hour” must include any

appropriate efficiency factors, so that it

represents the number of cycles actually

achieved per hour (see Table 2-1)

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Sorting of soils into groups each of which would show

similar behavior is the objective of soil classification.

Any soil classification system must provide us with

information about the probable engineering behavior

of soil

- Unified Soil Classification System (USCS)

-American Association of State Highway and Transport Officials (AASHTO) System

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• The US Occupational Safety and Health

Administration (OSHA) requires the classification

of soil to protect workers from injury when

working in excavations and trenches OSHA

uses 3 soil classification plus one for rock, based primarily on strength but also:

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The soil is fissured

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There are sources of vibration near the excavation

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Soil type A, B, C by OSHA

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Type C is the least stable type of soil

Unconfined compressive strength: Pressure required for

soil to fail under compression

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