Muck classification: raw material or waste in tunnelling operation.

Tunnel construction, structural diaphragms, debris from quarry exploitation require careful consideration of the spoil management, as this involves environmental, economic and legal requirements. In this paper a classification that considers the interaction between technical and geological factors in determining the features of the resulting muck is proposed. This gives indications about the required treatments as well as laboratory and field characterisation tests to be performed to assess muck recovery alternatives. While this reuse is an opportunity for excavations in good quality homogeneous grounds (e.g. granitic mass), it is critical for complex formation. It is therefore necessary to define a procedure that enables to assess the properties of natural ground and of the relative spoil or waste arising from the excavation or exploitation phases. This approach is presented in this paper for usual tunnelling cases, where the materials are resulting from the tunnel excavation carried out by drill and blasting and mechanised tunnelling. Physical parameters and technological features of the materials have to be assessed, according to their valorisation potential, for defining re-utilisation patterns. The methodology has proved to be effective in some cases tested by the Authors and the laboratory tests carried out on the materials allowed the suitability and treatment effectiveness for each muck recovery strategy to be defined

Tunnelling muck classification:definition and application

Excavated material management represents today a key issue due to environmental constraints and to the claim for possible reuse. Therefore, the knowledge of muck characteristics has become a topic of high interest. The muck can show different properties and behaviour, mainly due to the local geology, to the excavation mode and to the possible treatment. On the basis of the properties and of the possible local or remote recycling, the spoil can be processed in a treatment plant or sent to disposal. As the ground types can change along the tunnel, it is important to assess its variability in order to adapt the plant capability for producing a suitable by-product. For these reasons, a procedure for classifying the spoil from tunnelling is proposed (TMC). It represents a simple and practical tool for correlating ground type, possible muck destination and treatment type. Testing plan of the materials for the possible different muck destination should be compiled and conditions for safe waste disposal should be analysed as well

Tunnel spoil classification and applicability of lime addition in weak formations for muck reuse

Tunnel construction planning requires careful consideration of the spoil management part, as this involves environmental, economic and legal requirements. In this paper a methodological approach that considers the interaction between technical and geological factors in determining the features of the resulting muck is proposed. This gives indications about the required treatments as well as laboratory and field characterisation tests to be performed to assess muck recovery alternatives. While this reuse is an opportunity for excavations in good quality homogeneous grounds (e.g. granitic mass), it is critical for complex formation. This approach has been validated, at present, for three different geo-materials resulting from a tunnel excavation carried out with a large diameter Earth Pressure Balance Shield (EPB) through a complex geological succession. Physical parameters and technological features of the three materials have been assessed, according to their valorisation potential, for defining re-utilisation patterns. The methodology proved to be effective and the laboratory tests carried out on the three materials allowed the suitability and treatment effectiveness for each muck recovery strategy to be define

Large Scale Trials of Waste Mine Burden Backfilling in Pit Lakes: Impact on Sulphate Content and Suspended Solids in Water

The paper describes the results obtained from a large-scale trial designed to assess the impact of the backfilling of waste mine burden in an exhausted pit on the quality of lake water. The trial aimed at understanding the interaction between groundwater and clay and silty sand soils composing the overburden material. The two main environmental concerns related to the turbidity of the water and the concentration of sulphate ions. Tests were designed to (I) assess the interaction between soil and water; (II) measure the turbidity of water, related to the amount of solid particles in suspension; (III) observe the sedimentation of fine particles; (IV) measure the concentration of sulphate ions during backfilling and water pumping operations; and (V) validate an analytical model for the prediction of sulphate quantity in water. The main results indicated that the basin was capable to retain particles with sizes in the order of diameters that were nearly 10 microns. The water pumping was responsible for a relevant motion of fine particles (diameter less than 2 μm); this effect impacted on the turbidity level observed at the outflow in a relevant way. On the other hand, the test indicated that the estimation of the release of sulphate ions in the water was heavily affected by a proper assumption of the average background values of the concentration of sulphate ions in the water before the dumping activity