HiSCS successfully carried out the pull-out testing program for the passive support system of the utility tunnel as part of the overall Airport Expansion Program “Design & Construction for the Multi-Storey Car Park (MSP) and NW Apron (NWA).

The retaining system incorporated by Ø28 mm grouted soil nails, designed to provide passive reinforcement of the retained soil mass. The grouted soil nail consists of a steel bar installed in a drilled borehole permanently bonded to the surrounding soil using cement grout and the bearing assembly at the excavation surface. This type of soil nails are classified as passive reinforcement systems because they become effective only when the surrounding soil tends to deform, thereby mobilizing the bond stresses between the bar, grout, and soil.

The pull-out testing were conducted to assess the mechanical performance of the nails under tensile loading and to validate the geotechnical design predictions regarding the load-bearing capacity and failure limits of the nailing system. These tests are essential for validating that the installed nails meet the required performance criteria and provide the intended level of stability and safety for the excavation support system.

Testing was performed using a 200-ton hollow type hydraulic jack with a maximum stroke of 150 mm, enabling the controlled application of tensile loads while accurately monitoring the displacement response of the anchor bars throughout the loading process. The successful completion of the testing campaign confirmed the performance of the installed anchorage system and validated the geotechnical design parameters adopted for the project.