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"Important NOTE" Information Provided On This Website Is Intended For "GENERAL INFORMATION
ONLY" And Must Be Only Be Used Only As A "GUIDE" It Must Not Be Used For Decision Making, Or
Be Used For Any Building Purposes Or Legal Proceedings. Refer To Our Policies On This Website.

Site Investigations Are One Of The Basics Job Description
That A
 Structural Engineer Will Carry Out If Required.

Before commencing construction, the suitability of a site has to be assessed by doing a in depth on-site investigation of the surface and subsurface.

Surface explorations of the site could include advanced methods such as geological studies, geophysical
methods and, photo grammetry.

At times, only a visual inspection of the site is needed. Subsurface investigations will be more detailed.

SOIL SAMPLING:

Soil sampling consists of two varieties One is a ''small diameter'' and, the other is a ''large diameter''.
Large diameter boring's are rarely used due to cost and safety considerations.

Soil samples are categorized as "disturbed" and "undisturbed".

A disturbed soil is classified as soil whose properties have been sufficiently disturbed so that structural properties of the soil, if tested, will not reflect true in-situ conditions.

An undisturbed soil sample reflects soil conditions in-situ, that are relatively accurately.

SOIL SAMPLERS:

Soil samples are collected using a variety of implements and instruments. Some of the methods used in collecting soil samples are:

* Shovel - soil can be collected by digging out soil from the site.

* Hand or Machine driven auger - The auger digs deep into the soil... by a combination of force and rotary motion.

The soil taken in this method is classified as disturbed samples.

* Continuous Flight Auger - The auger works like a corkscrew and soil can be collected from the ground.

This soil is considered and classified as disturbed.

* SPT sampler - This is used for the Standard Penetration Test and Split Barrel Sampling of Soils.

* Modified California Sampler - it is similar to the SPT, but the sampler barrel is larger in size.

* Shelby Tube Sampler - this sampling method is used for cohesive soils. Soil samples collected using this sampler is considered to be undisturbed.

* Piston Samplers - it consists of a thin wall metal tube which has a piston located at the tip of the sampler. Soils collected using a Piston Sampler is considered to be undisturbed.

* Pitcher Barrel Sampler - it is similar to the Piston Sampler but, this sampler has no piston.

Remember, With Site Investigations The Following Tests
May Be Required Before Any Construction Can Begin.

STANDARD PENETRATION TESTS (SPT):

This is an in-situ dynamic penetration test which gives soil information!!! as well as takes, disturbed soil
samples for grain analysis and soil classification.

DYNAMIC CONE PENETRATION (DCP):

This is an in-situ test. Weight is manually lifted and dropped on a cone which penetrates the ground.

The number of mm that the cone buries itself per hit are recorded to find out certain soil characteristics.

These values have to be cross checked with lab data.

CONE PENETRATION TEST (CPT):

It uses a conical tipped probe containing instruments. This is hydraulically forced into the soil.

The tip resistance and shear resistance reading recorded is correlated with soil properties.

PIEZOCONE PENETROMETER (CPTu):

It is like the Cone Penetration Test, but the probe has additional instrumentation which measures ground
water pressure.

SEISMIC PIEZOCONE PENETROMETER (SCPTu):

It is similar to the CPT but, has instruments which can detect shear waves and/or pressure waves
which are directed to it from the surface.

FULL FLOW PENETROMETERS T-BAR, BALL AND PLATE:

These penetrometers are used in soft clay soils such as sea floors.

They are used to measure penetration resistance and, to estimate the un-drained plus the remolded
shear strengths. These penetrometers will give you a accurate data base to work off.

A wide variety of laboratory tests are carried out to determine a whole range of soil characteristics.

Some of the tests carried out measure direct properties of soil, while the others are used to measure
'indexed properties', which provide general information of the soil without quantifying actual properties.

The Lab Tests Which Are Usually Carried Out For Site Investigations Are:

* Atterberg limits - it defines the boundaries of several states of soil consistency for plastic soils.

The boundaries are termed as plastic limit & liquid limit & the difference in these two is the plasticity index.

* N.S.W Sydney bearing ratio - it determines the suitability of soil or aggregate samples as a road sub grade.

* Direct Shear Test - It determines the consolidated, drained strength properties of the soil.

* Expansion Index test - used to determine the Expansion Index.

* Hydraulic Conductivity Test - this test is carried out using constant head, falling head and constant flow methods. It can be used to test all types of soil.

* Oedometer test - it is used to determine soil consolidation and swelling.

* Particle size analysis - used to determine soil gradation.

* R-Value Test - it measures the lateral response of the sample, to vertical pressure, under specific test conditions.

* Soil Compaction Tests - it is used to determine the maximum unit weight plus optimum water content
which can be achieved by the soil, for a given compaction effort.

* Triaxial Shear Tests - It determines the shear strength properties of soil.

* Unconfined Compression Test - this test measures the strength of the soil sample.

* Water content - it is used to determine the water content of the soil.

Site Investigations Are A Vital Part Of Any Project.

If the site conditions are not determined correctly, during construction, a lot of unforeseen problems may arise, which may lead to delays and cost escalations and even catastrophic failures.


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Videos Are Under Construction They Will Be Uploaded Soon
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"Important NOTE" Information Provided On This Website Is Intended For "GENERAL INFORMATION
ONLY" And Must Be Only Be Used Only As A "GUIDE" It Must Not Be Used For Decision Making, Or
Be Used For Any Building Purposes Or Legal Proceedings. Refer To Our Policies On This Website.

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