Chapter 1 Substructure

8/11/2019 Chapter 1 Substructure

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CHAPTER 1 SUBSTRUCTURE

1.1 Earthwork


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INTRODUCTION Earthwork: the processes whereby the surface of the

earth is excavated and transported to and compactedat another location.

The introduction of the internal combustion engine,electric power and hydraulic power have led to thedevelopment of a wide range of earthwork plant (size,capacity and efficiency).

Scale: ranges from small works (the excavation ofditches and trenches for drainage and pits and trenchesfor foundations) to the large earthworks (highways anddams).


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INTRODUCTION carried out at an early stage in a construction project,

completion of the earthworks within the scheduledtime is often the key to the completion on time of thewhole project

success often depends on:

o an adequate site investigation and preparingpractical and satisfactory designs of theearthworks.

o the choice and efficient use of the correct typesand size of plant to meet the particularrequirements of the site.


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SCOPE OF EARTHWORKS

Site clearing (Pembersihan tapak)

Cutting and excavation (Pengorekan dan pemotongan)

Transport and moving (Pemunggahan,Pengangkutandan Penuangan)

Compaction (Pemadatan)

Sloping (Pencerunan)


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Site clearing

Clearing, grubbing, demolishing, breaking up andremoving all trees, shrubs, vegetation, butts,structures such as walls, fences and other obstructionwithin the site which have been designated to bedemolished or removed

All spoils and debris shall be removed and disposed ofoff-site at an approved certified construction landfill


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Site clearing


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Cutting and excavation

Most construction projects require the movement ofearthwork on site. This will result in altering theexisting elevation to a different or finish elevation.

To determine the amount of soil to be moved, theestimator needs to have a plot plan or topographicsurvey.

This drawing is developed by plotting the readings(elevations) obtained from a topographic field surveyusually performed by a licensed land surveyor.


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Part of the permanent works (e.g. cuttings)

A temporary expedient in the construction of theworks (e.g. for foundations and drainage)

The sides of the excavations are required to remainstable during their design life, can be achieved by: excavating the material to a stable slope angle

by retaining or supporting the material.


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Transport and moving

Trucks are used to transport excavated material,aggregates and construction material

As the primary hauling unit provides a high degree of

flexibility. Found in the crust of the earth

Classified as rock or soil

Soil characteristics that affect a soils behaviour forconstruction purposes.


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Lab tests are required to fully determine a soils

physical and chemical properties which control those

characteristics.


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Compaction

Increased bearing capacity

Increased compressibility

Reduce permeability Improve stability

Heavy/highway vs. building foundation compaction

operations


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Compaction


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Sloping

Function of the natural angle of repose, density,surface and subsurface water flow.

Early stabilization of surfaces is critical

Eliminate points of concentrated flow using slopedrains as outlets.

Difficult slopes may require riprap, gabions, or othermeasures for permanent stabilization .


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Sloping


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Sloping


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KEYS TO SUCCESSFULEARTHWORK OPERATIONS

1. Control surface and subsurface water

2. Maintain optimum moisture range by drying, mixing ,

or wetting3. Identify and monitor cut & fill quantities

4. Good layout (horizontal & vertical control)

5. Minimize handling - minimize stockpiling


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KEYS TO SUCCESSFULEARTHWORK OPERATIONS

6. Optimize haul lengths

7. Minimize cycle time

8. Proper selection and sizing of excavators and haulunits

9. Alternate haul unit wheel paths

10. Experienced personnel in the field

Chapter 1 Substructure

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