Exploratory Drilling and Soil Surveys
Exploratory drilling provides a basis for the design of engineering projects – residential buildings, office towers or infrastructure works of any type – at its most fundamental level. The depth of test drilling is derived from the depth of impact of the structural foundation and its functional requirements.
Exploratory drilling is a basic tool used by geotechnical engineers in order to determine strength parameters of the soil and in order to define other soil properties such as permeability that will enable assessment of the behavior of the soil-structure interface. Exploratory drilling is performed in accordance with the precise instructions of the geotechnical engineer and relevant standards. In many cases, it is accompanied by on-site supervision by a geologist who documents the soil or rock in real-time as it is extracted from the borehole. Several types of in-situ tests can be performed.
The most common and simplest to perform is standard penetration testing (SPT). Due to its prevalence of use, numerous correlations have been developed between the results of this test and the various engineering properties of the soil being tested, as for example angle of internal friction and relative density. Undisturbed samples can be extracted during test drilling from various depths. Various laboratory tests can be performed on the samples such as strength tests or indicative tests that supplement information about soil properties that are required for purposes of proper design at the soil-structure interface.
Pamco Engineering performs even more complex in situ tests, as for example borehole photography using acoustical or optical probe cameras to depths of more than 500 m (borehole TV), measurement of borehole diameter in order to study areas tending to collapse (caliper), and various geophysical tests such as P/S or full wave sonic tests. (These tests may also be performed by specialist subcontractors). Continuous core samples of the drilled material can be extracted from boreholes in rocky strata. The extracted cores are then stored in special boxes and are numbered and cataloged according to location and depth. Unique in-situ tests can also be performed in rocky strata (as well as in soft soils) such as pressiometer tests, hydrofracturing or hydrojacking.