Key Takeaways
In recent times Compact Lightweight Drilling and Sampling Machines have become very popular.
Several companies manufacture excellent compact soil sampling machines including Dando Terrier, Archway Competitor, and Premier Plant.
Equipment for this ground penetration and sampling method can be quickly deployed using a trailer behind a 4×4 vehicle or inside a panel van. These generally rubber-tracked machines can move swiftly around a site, causing minimal surface damage while obtaining high-quality, representative samples of strata beneath the site, typically to depths of around 10 meters. Under favorable conditions, this depth can be significantly increased.
Drilcorp performs this work using machines equipped with a drop hammer, which can be rapidly swapped with a rotary drill head to enable penetration into bedrock, including coring to depths of up to 50 meters.
Photo by piyaset
On many sites it is necessary to cut through concrete or tarmac and other man made materials in order to gain access to the ground that is to be investigated. A concrete cutting/coring barrel is used for this and consists of a tube with a diamond impregnated shoe easily capable of cutting the hardest of materials including reinforced concrete. The top of the tube is fitted with a water swivel for injection of water to cool the bit and clear drill cuttings.
Window sampling tubes are usually 1mtr – 2mtr long. They have a cutting shoe on the leading edge and slots or windows up the side which give direct access to the sample. They are driven into the ground by a drop weight or hydraulic hammer. Casing is advanced during sampling when needed to stabilise collapsing strata.
Other similar types of sampling tubes have no windows (windowless) but have removable clear plastic liners which can be sealed to maintain integrity and then cut open along their length in the laboratory where they are logged, analysed and samples are tested giving excellent representative information on the site being investigated.
Other geotechnical information can be gathered during this type of ground investigation.
A test to estimate the degree of compactness of soil in place by counting the number of blows required to drive a standard sampling spoon 1′ (0.3 meter) using a 140 pound (64 kilogram) weight falling 30″ (0.8 meter).
Dynamic Probing (BS 1377 Part 9)
This test is done to determine the penetration resistance of soil and consists of dropping a hammer onto an anvil over a distance of 300mm and at a rate of between 20 and 60 blows per minute. The anvil is directly connected via rigid rods to the probe which is resting on the strata at the base of a hole. Blows are counted and recorded for every 100mm of penetration.
U100 Sampling
This is a sampling method whereby a sampling tube is driven into the ground (usually clay type material). Samples are retained in the tube by fingers at the base which grip when the tube is lifted from the base of the hole. There are several systems of U100 samplers – U100 Standard System, U100 Plastic Liner System & U100 Thin Wall System.
Photo by BartCo
Soil sampling is an essential component of geotechnical and environmental investigations, offering a multitude of benefits that ensure the success and safety of construction projects and environmental assessments. By extracting and analyzing soil samples, engineers and environmental scientists can gain invaluable insights into the subsurface conditions, which in turn supports informed decision-making and project planning.
Soil sampling provides a direct and precise method of understanding the subsurface conditions of a site. By collecting samples from various depths, it is possible to determine the composition, stratification, and physical properties of the soil. This information is crucial for evaluating the stability and suitability of the ground for construction, as well as for identifying potential hazards such as soft spots, voids, or areas of contamination.
Understanding the soil composition and its behavior under different conditions helps in mitigating risks associated with ground instability or unexpected soil conditions. For instance, the results from Standard Penetration Tests (SPT) and Dynamic Probing provide data on soil compactness and strength, which are critical for ensuring the structural integrity of foundations and preventing issues such as settlement or landslides. By proactively addressing these concerns, soil sampling contributes to the safety and longevity of construction projects.
Soil sampling is instrumental in environmental assessments, particularly in detecting contamination and assessing the potential for soil and groundwater pollution. By analysing soil samples, it is possible to identify the presence of hazardous substances, such as heavy metals or hydrocarbons, which may pose risks to human health and the environment. This information is vital for developing remediation strategies and ensuring compliance with environmental regulations, thereby protecting ecosystems and public health.
Accurate soil data obtained from sampling allows for more efficient project planning and resource allocation. By understanding the soil conditions upfront, engineers can design foundations and structures that are well-suited to the site’s characteristics, thereby avoiding costly redesigns or construction delays. Additionally, identifying potential issues early on through soil sampling can prevent unexpected expenses related to soil stabilisation or contamination cleanup.
Different sites present unique challenges, and soil sampling methods, such as U100 Sampling, Concrete Coring, and Window/Windowless Sampling, can be tailored to suit the specific requirements of each project. This adaptability ensures that the most relevant and accurate data is collected, regardless of the site’s complexity or the depth of investigation needed.
Contact Drilcorp for UK-wide drilling and borehole services for both business and home needs, including geothermal and environmental solutions.
