GNGTS 2014 - Atti del 33° Convegno Nazionale

sand (95% SiO2) characterized by a diameter average equal to 0.09 mm (very fine sand), a porosity of about 45 ÷ 50% and hydraulic conductivity in the order of 10 -5 ms -1 . In the Tab. 1 are presented the results of chemical, particle size and hydrogeological analysis obtained by laboratory tests. Tab. 1 - Chemical analysis, Particle size analysis, Hydrogeological properties. Chemical analysis SiO 2 Al 2 O 3 Fe 2 O 3 CaO K 2 O % 93.00 2.50 0.60 1.50 1.15 Particle size analysis d (mm) 1 – 0.5 0.50 - 0.25 0.250– 0.125 0.125– 0.063 0.063– 0.032 > 0.032 % 0.00 0.14 3.70 86.34 7.92 1.08 Hydrogeological properties d m (mm) K max (m/s) ρ (%) 0.09 4*10 -5 45 – 50 Fig. 1 shows the various components of the experiment and a view of the instrumented sand box. The box is height 90 cm and is an inverted truncated cone characterized by a base diameter of 90 cm and a top diameter of 120 cm. On the base where a drainage system was located, a steel slab was inserted near the interface between sand and gravel to have a strong reflection when GPR acquisition are made. Respectively ad a depth of 30 and 45 cm from the ground surface a pvc pipe (diameter 32 mm) and a steel rode (diameter of 12 mm) were inserted to have electromagnetics anomaly in GPR analysis. Below the layer of sand, at the base of the vat, has been placed a layer of pebbles of height equal to 4 cm; the two materials were separated with a sheet of geotextile. With this layer was simulated a drainage system that allows to recharge the vat continuously during the pumpis process. Fig. 1 – Plan of the test site and experimental set-up at CNR-IMAA “Hydrogeosite” laboratory in Marsico Nuovo (PZ-Basilicata). GNGTS 2014 S essione 3.3 217