Naples – Bari high speed railway project. Rocchetta, Melito and Grottaminarda tunnels. Critical analysis of studies, investigations and design and construction solutions proposed by the Contractor for line and service tunnels construction in gassy rock masses

Client: Italferr SpA
Project: Naples – Bari high speed railway project. Apice – Hirpinia Section. Rocchetta, Melito and Grottaminarda tunnels
Date: February 2022 – May 2023

The Detailed Construction Design (DCD) of Hirpinia AV Consortium (Contractor) for the “Apice-Hirpinia” Sector of the new Naples – Bari High Speed / High Capacity railway line involves the construction:

  • with EPB – TBM, of the three line tunnels (Figure 1):
    ◦ Rocchetta (long approximately 6,4 km);
    ◦ Melito (long approximately 4,4 km);
    ◦ Grottaminarda (long approximately 2,0 km);
  • with traditional technique, of service tunnels (Figure 2) and vehicural and pedestrian emergency tunnels.

Italferr entrusted SERENGEO to critically analyse and comment studies, investigations and design and construction solutions proposed and adopted by the Contractor for DCD of line and service tunnels.

 

Figure 1. Route of Rocchetta, Melito and Grottaminarda tunnels and of the service tunnels

Figure 2. Service tunnels of the three line tunnels

Objectives

  •  Assess the adequacy of the methane emission model and of the technical and technological solutions developed and adopted by the Contractor for excavation, with EPB – TBM, of Rocchetta, Melito and Grottaminarda tunnels and, with full-face method and traditional technique, of the small section service tunnels (<70 m²);
  • Provide guidance and recommendations for the detection of methane emissions during geognostic borehole drilling and for the monitoring of instrumented boreholes.

Activities performed

  1. In-depth study of technical and scientific literature (Figure 3) and design documentation relating to studies and investigations performed during the various design phases (Definitive Project, Executive Project PE and PED, Figura 4) to characterize the geological formations crossed by the three line tunnels and service tunnels route;
  2. Examination of the design (PE, DCD) solutions adopted by the Contractor for excavation with EPB – TBM of the three line tunnels and with full-face method and traditional technique of the service tunnels;
  3. Critical analysis and observations on:
    ◦ results of geognostic and methane investigations conducted during the various design phases along the tunnel route;
    ◦ methane emission model developed by the Contractor;
    ◦ design solutions developed and adopted by the Contractor for excavation of the three line tunnels and of the service tunnels;
  4. Writing of technical recommendations for the detection of methane emissions during geognostic borehole drilling and for the monitoring of instrumented boreholes along tunnels tracks.

Figure 3. Methane evidences in the area surrounding the three tunnels’ route

Figure 4. Boreholes along the Apice – Hirpinia route, in which methane concentration measurements were performed in 2017. The measured values are reported next to each borehole.