ABSTRACT

ABSTRACT:

A new approach to rock and soil abrasivity testing is presented focusing on the needs of underground excavation. The abrasivity assessment is based on the LCPC Abrasivity Test which was developed by the Laboratoire Central des Ponts et Chaussées in the 1980ies. The LCPC Abrasivity Coefficient (ABR or LAC) can be used as a measure for both the abrasivity of the material and the influence of the grain size. A calibration chart has been established using different artificial and natural granular materials, containing both rounded and angular grains, different rock materials and especially highly abrasive material such as quartz and non abrasive material such as limestone. This chart allows the classification of different materials using the background of tool wear and drillability problems. Applied in the correct framework of geological and geotechnical investigations, the LCPC test allows a reliable, quick and hence, cost effective assessment of the abrasivity of rock and granular materials.

1 SCOPE

Numerous methods exist for determining abrasivity of hard rock, however very few are established in the field of coarse granular materials of sand and gravel size. This is due to the fact that there is a long tradition of predicting e.g. Although this might not apply to the same extent for coarse granular material, such as gravel and sand, soil abrasivity can have a significant impact on the performance of shielded TBMs or large diameter drillholes in soft ground. Also in soft ground, a reliable prognosis of the abrasiveness of the soil material would be of great value for the designer as well as the client and the contractor in order to calculate the tool costs and to minimize underground risk. This paper contributes to the actual discussion of TBM wear prediction in soft ground.

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