Soil improuvement through vertical jet-grouting columns - A centrifuge study

The paper reports the results of the physical simulations performed by the geotechnical centrifuge concerning the improvement of a soft artificial soil deposit by means of vertical jet-grouting columns. Such technique was adopted to allow the construction of about 50m high municipal waste landfill over a fine tailings deposit resulting from the activity of a sand and gravel borrow quarry operating in an alluvial site near Gorla (Northern Italy). The results obtained demonstrated the capability of the centrifuge tests to ascertain the influence exerted by the main factors controlling the settlement of the reinforced soil. Some doubts still exist about the importance of possible scale effects concerning the modelling of the soil inclusion interface behaviour. However, due to the shortcomings of the design methods commonly used, the centrifuge tests can be considered a valid complementary tool for the design of such soil reinforcement technique

Interface behaviour of sands from constant normal stiffness direct shear tests

This paper report san experimental study concerning the frictional behaviour of sand-solid structure interface. The study was performed using a constant normal stiffness (CNS) direct shear box. Three natural silica sand and four aluminium plates with different roughnesses were investigated. A comparison between constant normal load (CNL) and CNS tests is reported. The influence of the main factors controlling the frictional behaviour of the investigated materials are analized and discussed