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Drilling is the most common and simplest method of reconnaissance of ground-rock substrate. It consists in drilling a borehole and exploration of the material obtained in this way. This method is implemented by a variety of techniques, depending on the geological structure, purpose, depth, sampling requirements. We distinguish the following drilling techniques:
This is the simplest and most common form of diagnosis of shallow ground, particularly in places inaccessible for heavy equipment Thanks to their mobility are most commonly used for linear objects such as roads, railway lines, gas pipelines. The diameter of such drilling range from 65-90 mm and is tailored to any piping hole if you encounter the table of groundwater.
This is the method of diagnosis of the ground up to several metres by using different diameter probes. Using the hammer with internal combustion engine, samplers penetrates the ground, fill the the excavated material, and next are extracted and described. This method is useful in places inaccessible to heavy equipment where it occurs shallow groundwater table and in places where it is impossible to use a hand drillings because of the “heavy” soil or thick layer of the railway embankment.
Mechanical drillings auger and core
Mechanical drilling is done when you need to make boreholes with a depth of more than a dozen meters, or when there are extremely difficult terrains, shallow level of water table, stony and rocky soil. Drillings can be divided into auger drillings, performed using spiral drill, which is the simplest system of this type of drilling. The holes may be cased by pipes in the case of encountering shallow aquifer, purpose of their isolation. In this technique drillings can be carried out to a depth of about 25-30 m below ground level. Under favorable conditions from the bottom of the borehole can be taken samples of the soil with intact structure, or perform additional tests such as SPT or FVT probing.
Core drillings, which are a more advanced form of mechanical drillings are particularly useful for the diagnosis of rocky soils, tracks, roads or airports and places where is the need of intact structure sampling. Core drillings are also recommended for the examination of landslides and is placed in guidelines for research of highways. This type of drilling allows continuous observation of intact soil profile. Core drillings are applied in engineering geology and hydrogeology.
A special place among the mechanical drilling deal reamer bit drilling and hammering with upper or lower hammer. This type of drillings is mainly carried out in order to verify the information of the rock structure, eg with geophysics. They allow the general recognition of the substrate by mud logging, or the material drawn on the sieves. Drilling these are also useful as a preparation for geophysical measurements like uphole, crosshole, or as blasting holes for seismic dynamite.