Soil drilling
An experimental soil drilling project for sampling (also known as trial drilling), in the process of formulating the soil report before the construction project, is a central and essential component that cannot be done without.
Soil drilling - why?
As part of the soil survey, samples are taken in the field through a series of drillings aimed at collecting soil samples at the designated locations and depths based on historical mapping of the site. The purpose of testing the soil as part of the drilling is to determine stability, the type and quality of the soil and allow the engineer and constructor to submit recommendations for the infrastructure of the future construction project.
The professionality and thoroughness of the various stages in the drilling and sampling process has a significant impact on the ability to analyze and formulate recommendations later and therefore on the nature of the planned construction project.
The considerations for the experimental soil drilling contractor are based on the instructions of the soil consultant and the historical mapping as well as an examination of the actual sampling site and considerations of accessibility, coverage and clarity of the sampling products.
Types of soil drilling for sampling - methods and considerations
There are several methods performing soil drilling for sampling and the tools they use accordingly.
The main considerations, in choosing the drilling method and tool, are:
1. Accessibility of the sampling site (restricted access, electricity/water infrastructure, closed building, etc.).
2. The depth and diameter of the drilling, according to the planned construction.
3. The type of soil.
4. The purpose of the project (private, commercial, public or other construction).
For example, for private construction the accepted drilling depth is about 12 meters, while for a building about 24 meters.
Therefore, according to the afore mentioned limitations, drilling is possible with the following methods:
1. Mechanical drilling tower - deep soil drilling, only on a site with high accessibility.
2. A mechanical drill on a truck - intended for great depths and difficult soil types.
3. A mechanical drill on a tractor with the ability to tilt - suitable for sites with limited accessibility, but not for deep drilling.
4. Hydraulic hand drill (mechanical) - limited in medium depth and diameter of operation, but suitable for sites with limited access even for a tractor drill.
5. Manual drill - limited in the depth and diameter of the operation and according to the physical ability of the driller, but suitable for sites with limited access even for a tractor drill.
Types of drilling:
1. Core drilling (HQ wireline rock): designed for rocky soil.
2. Spiral drilling (hamster): designed for dry or sandy soil.
3. DCP drilling: soil density test designed for mapping the location of the layers, thickness and determination of soil strength (more on DCP drilling, here).
4. SPT drilling: drilling to evaluate the density of the soil, using a special tubular drill (more on SPT drilling, here).
Of course, the more drillings are carried out, the richer information is obtained and which enables a more accurate and reliable decision to be made. However, the land consultant together with the constructor knew how to optimize the layout of the drillings according to professional considerations and such as those detailed above.
Selection of soil drilling services
There is a large variety of soil drilling contractors on the market, so it is important to examine several alternatives of service, methods and price.
Of course, you should not hire the services of a contractor who has not received recommendations and the products of his work have not been tested and accepted by the soil consultant you have chosen to contract with. In certain cases, the soil consultant himself will recommend to you the services of a drilling contractor that he works with on an ongoing basis and therefore trusts the professionalism of his work products - which, as mentioned, are essential for producing a professional land report.
However, the soil consultant should be required to specify the requirements and products from the soil drilling and to allow a market survey between different contractors.