The objective of any insitu testing company during in-situ testing is to identify the sequence and nature of the subsurface strata, the groundwater conditions, and the mechanical and physical properties of the subsurface strata. For geo-environmental investigations where contaminants are possible, the abovementioned objectives have the additional requirements to determine the composition and distribution of contaminants.
The requirements mentioned above are a function of the proposed project and any associated risks. An ideal program investigation should include a mix of lab and field tests depending on the risk of the project.
Cone penetration
The cone penetration and its enhanced versions have extensive applications in a variety of soils. Although the cone penetration is limited to softer soils, with advanced and larger pushing equipment, the cone penetration can be done in stiff soils and, in some cases, soft rocks.
- Disadvantages of the cone penetration
Cone penetration has some disadvantages including high capital investment, no soil sample, requires skilled operators and penetration can be restricted in cemented or gravel layers.
- Advantages of the cone penetration
Cone penetration has several advantages including repeatable and reliable data, fast and continuous profiling, it’s economical and productive, and a strong theoretical basis for data interpretation.
The standard penetration tests
The standard penetration test is used as an indicator of stiffness of granular soils and relative density as well as an indicator of consistency in a wide array of other ground. Methods have been developed to apply the standard penetration test results in a wide range of geotechnical applications such as deep foundations and shallow foundations and the assessment of liquefaction potential.
- Disadvantages
Just like any other type of insitu testing, the standard penetration test has some disadvantages such as crude number, disturbed sample, not being applicable in silts and soft clays and high uncertainty and variability.
- Advantages
There are several advantages associated with the standard penetration test such as its low cost, availability throughout Australia, and it can be done in most types of soil.
The field vane test
This test is used for the evaluation of the undrained shear strength of silts and soft to stiff clays. Both the remoulded strengths and peak strengths can be measured and their ratio is listed in soil sensitivity.
- Disadvantages
There is a limited application to silts and soft to stiff clays, slow and time-consuming, can be affected by seams and sand lenses.
- Advantages
This test is simple and requires simple equipment. It has been in practice for a very long time and that is why a lot of engineers are familiar with it.
The standard penetration tests
This test is used as an indicator of stiffness and relative density of granular soils and as an indicator of consistency in other grounds. There have been several methods developed to apply the standard penetration test to a wide range of applications including deep and shallow foundations and assessing the liquefaction potential. An insitu testing company may prefer this method since it is cheap, simple and rugged and can be performed in most types of soil.
