Consultancy for the design of an innovative excavation system by hydrodemolition and thrust for the construction of vertical wells in soils

Client: Palmieri Tunnelling SpA
Project: Cuenca Matanza – Riachuelo environmental restoration system project
Date: 2017-18

SERENGEO provided technical-scientific consultancy for the design of an innovative system (Riser Concept) for the construction of vertical diffusers in soils (Figure 1) by hydrodemolition and thrust, part of the “Sustainable development project of Cuenca Matanza Riachuelo – Lote 3” (ATI Salini Impregilo SpA – SA Healy Company, https://www.webuildgroup.com/en/projects/dams-hydroelectric-plants/riachuelo-environmental-restoration-system) at the mouth of the Rio de la Plata (Buenos Aires, Argentina) .

Project goals

  • Technical-scientific support for the design of the innovative excavation system;
  • Evaluation of the technical feasibility of wells excavation, with the innovative technology, in the soils involved by the project;
  • Critical analysis and support in defining the procedures to be adopted in the “scale tests” for “Riser Concept”’s validation.

Activities performed

  1. Scientific iterature review and critical analysis on:
    • behavior of soils (clays and sands) under indentation;
    • waterjet technology applied to soils;
    • parameters influencing the soil excavability by hydrodemolition;
  2. Study of the feasibility of wells excavation by hydrodemolition and thrust in the soils (clays and sands) involved by the project;
  3. Estimation of jacking force required for risers’ construction (Figure 3);
  4. Critical analysis of investigations carried out by ATI (in situ and laboratory tests) to characterize the soils to be excavated in situ and the soils selected in Italy for “scale tests”;
  5. Proposal for a supplementary geognostic in-situ survey;
  6. Critical analysis and support in the design of:
    • the excavation system;
    • the procedures for “scale tests” developed by ATI;
  7. Assistance in performing the “scale tests” and critical analysis of the results .

Geotechnical profile of the project area based on the results of the geognostic survey campaign performed in 2015

Minimum (a, stratigraphy of borehole SDF-ST1) and maximum (b, stratigraphy of borehole SCT-ST1-B) jacking force required for risers’ construction.

Example of data recording during “Displacement Head test”