Porous Alpha for mechanized tunneling applications

Effectiveness study of Porous Alpha product for soils and rocks from mechanized tunneling applications

At the end of the experimental activities described in the document, it was achieved quite good knowledge, however preliminary, about the behavior of the Porous Alpha product for soils and rocks from EPB-TBM mechanized tunneling applications.
It is believed that the information acquired is enough to provide a general idea of the effectiveness of the product and it seems clear that it possesses all the features to be used after the mechanized excavation with EPB-TBM technology and particularly for soils with high water contents and thus low workability and poor mechanical strength characteristics in order to allow its proper management.

With reference to the performed tests, it is possible to list few conclusions:

the Porous Alpha product can be proposed and used in place of synthetic or semi-synthetic polymers for specific tunneling applications;
through the soil treatment with Porous Alpha product, it is possible to absorb part of the excess water present into the soil and thus improving its overall behavior and increasing its workability;
on coarse-grained soils (sand and gravel) the use of Porous Alpha product in granules seems to be more appropriate considering the grain size distribution and the need to fill high volumes of voids;
for fine-grained soils (silt and clay) the use of Porous Alpha product in powder or a combination of powder and granules seems to provide better results;
the addition of Porous Alpha product, in fine-grained soils, led to a time-dependent effect during the first 48 hours after the treatment which progressively increase consistency, mechanical strength, and workability of soil;
it is possible to reduce/optimize in a relevant way the amount of Porous Alpha required to obtain an increase in consistency, workability, and mechanical strength of the soil.

Earth Pressure Balance Tunnel Boring Machine Porous Alpha for mechanized tunneling — Earth Pressure Balance, Tunnel Boring Machine

laboratory soil conditioning Porous Alpha for mechanized tunneling — laboratory soil conditioning

Finally, it should be noted that the laboratory activities described in this document were aimed at testing the general effectiveness of the product tested in proper conditioning of some laboratory samples of natural soils and that therefore, in case of applications in a specific project, the dosage of the Porous Alpha product has to be determined by specific tests carried out using the soil coming from the real site.

Grain size distribution of Rome sand A, Rome clay A and Rome clay B.

Casagrande plasticity chart of Rome clay A and Rome clay B.

conditioned Rome clay B Porous Alpha for mechanized tunneling — conditioned Rome clay B

conditioned Rome clay B treated with 15% of Porous Alpha after 10 minutes Porous Alpha for mechanized tunneling — conditioned Rome clay B treated with 15% of Porous Alpha after 10 minutes

conditioned Rome clay B treated with 15% of Porous Alpha after 48 hours Porous Alpha for mechanized tunneling — conditioned Rome clay B treated with 15% of Porous Alpha after 48 hours

over-conditioned Rome clay A Porous Alpha for mechanized tunneling — over-conditioned Rome clay A

over-conditioned Rome clay A treated with 5% of Porous Alpha Porous Alpha for mechanized tunneling — over-conditioned Rome clay A treated with 5% of Porous Alpha

over-conditioned Rome clay A treated with 27% of Porous Alpha Porous Alpha for mechanized tunneling — over-conditioned Rome clay A treated with 27% of Porous Alpha

This report was performed by Geotechnical and Environmental Engineering Group a Startup Company of “Sapienza” University of Rome

Summary of the laboratory activities