Abrasiveness of coarse-grained soil - abrasion of drilling tools

Optimization of the laboratory test, development of a classification scheme, comparison of laboratory and site measurements

During construction work in soil material, abrasion occurs on the tools of the construction machines. The intensity of tool abrasion (=unwanted material removal) depends on a large number of influencing factors. From the point of view of the soil, the mineralogical composition, the grain sizes, the grain shapes, the grain size distribution, the water content as well as the density determine the abrasion potential.

For the determination of the abrasion potential, the so-called Vienna Abrasimeter was developed by Petra Drucker in the soil mechanics laboratory of TU Wien between 2010 and 2013; it is a further development of the LCPC test with the advantage that now also coarse-grained soil samples (grain size from 0.063 to 31.5 mm) - both in dry and wet condition - can be investigated. Furthermore, the new test procedure was standardized in October 2013 with the ÖBV bulletin "Abrasivitätsbestimmung von grobkörnigem Lockergestein".

Since then, numerous tests with the Vienna Abrasimeter have been carried out in the soil mechanics laboratory. The knowledge gained from these tests is to be incorporated into a revision of the ÖBV bulletin in order to optimize the performance of the test.

In addition, a classification scheme is being worked on in order to be able to classify the investigated soil with regard to its abrasion potential (e.g. low abrasive, medium abrasive, high abrasive) on the basis of the characteristic value determined in the laboratory (abrasiveness index AIW). Such a classification scheme shall be established for the dry condition as well as for the wet condition (e.g. for work in groundwater). This classification scheme should help to better estimate the tool abrasion to be expected on the construction site in advance.

In this context, measurements were also carried out on a construction site in Vienna as part of a master thesis in order to document the actual tool abrasion during bored pile work in Danube gravel. Parallel to this, laboratory tests were also carried out with the Vienna Abrasimeter in order to be able to compare the laboratory values with the measurments on the construction site. It is planned to carry out such measurements on other construction sites as well in order to create a corresponding data basis for further construction methods and other coarse-grained soils.

Photo and sketch of the experimental unit with explanation of the individual components.

© ÖBV-Merkblatt

Construction of the Vienna Abrasimeter.

In a laboratory room, two experimental units stand side by side.

© TU Wien, Institute of Geotechnics

Test equipment in the soil mechanics laboratory (left: Vienna abrasimeter; right: LCPC test unit).

Frontal view of a cutting wheel.

© TU Wien, Institute of Geotechnics

Cutting wheel of a tunnel boring machine.

On a table are 4 flat chisels; behind them a sheet with the measured masses.

© TU Wien, Institute of Geotechnics

Mass determination of worn flat tooth bits of an auger.

An auger is lying on the ground; a man can be seen on the right measuring the auger.

© TU Wien, Institute of Geotechnics

Wear documentation of a drilling auger on the construction site.