Influence of the soil conditioning additives on the adhesion problems in clayey soils and feasibility study for soil conditioning of rock masses for EPB tunnelling

The aim of this thesis is the demonstration that tunnelling with EPB technology can be applied also in geological conditions considered out by the common applications range as in rock masses, and that the proper combination of conditioning additives can face some common problems that can occur in difficult soils for EPB tunnelling as clayey soils. In the first chapter a general overview of the EPB technology is carried out describing the most important technical features, the working principle and the common application fields of this kind of TBM. The second part of this chapter is an overview of the soil conditioning techniques and of the soil conditioning additives used in EPB tunnelling. The second chapter is the resume of the technical literature review about conditioned soil testing. This literature analysis has been carried out studying foe each soil conditioning research topic the commonly used tests and the different tests proposed by many authors of different technical universities from all over the world. This research has been considered necessary to understand the state of art of soil conditioning testing in order to perform a research able to fill some research fields non yet deeply studied. The third chapter is the descriptions of all the soil conditioning test that can be performed in the Tunnel and Underground Space Center laboratory of Politecnico di Torino where the tests reported in this research has been carried out with both commonly used and standardized test procedures, with experimental devices designed during the almost ten years of history of this laboratory and with specific test studied, designed realized and tested during this research. The fourth chapter is a research carried on with the aim to observe the differences between some commercial soil conditioning additives commonly used for the treatment of clayey soils. The research has been carried out using three different clayey soils and four soil conditioning additives. Four different test procedure has been used to evaluate the behavior of the soil conditioned with the different products. The first tests carried out have been the slump test and the vane shear test in order to assess the proper set of conditioning parameter that allows the change of behavior of the clayey soil in a suitable conditioned muck. To evaluate the influence of the different products on the adhesive features of the conditioned soil two specific test have been studied during this research. The results of this research are described and discussed at the end of the chapter. In the fifth chapter are reported the tests and the results carried on with the aim to verify the possibility to properly treat the muck of a rock TBM in order to apply the EPB technology also in rock masses. This research has been started studying the possible grain size distribution of the much of a EPB TBM with rock tools by the data collected in technical literature. When assessed a range of grain size distribution considered simulative of the TBM muck, a slump test campaign has been performed for each one of the three geological formations studied. The conditioning parameters assessed with the slump test campaign have then been verified with screw conveyor extraction tests performed with the specific experimental test apparatus realized in Politecnico di Torino with very interesting results. All the test carried out during this research are described and the results are discussed at the end of the chapter.