Innovative approaches in artificial ground freezing application

The applicability of an innovative composite material called 'pykrete' made from a mixture of ice and sawdust, was investigated. The mechanical characteristics of pykrete material were determined according to the gradation of sawdust, density, and freezing temperature to produce a novel temporary retaining structure. The findings indicate that the novel pykrete substance, including the weight of 18% fine-grained pinewood sawdust, exhibited the properties suitable for a strong composite material since it has a compressive strength of 4.83 MPa. The usability of an artificial ground freezing (AGF) approach was evaluated via a dual independent closed-circulation mechanism that maintains a temperature of –15.00 °C for a duration of 48 hours within the scope of providing undisturbed sampling of granular soils that maintain their natural conditions. Thermal modeling was conducted using Plaxis 2D software. The empirical validation of the proposed sampling methodology has demonstrated its ability to capture on-site behavior accurately. A comparative model of an actual diaphragm wall, which is located in the El Harrach Center metro station project in the Algerian capital, with and without thermal impact, as well as a pykrete retaining structure, was simulated. After conducting modeling on 216 different cases via the Plaxis program, an effective scenario was identified. The pykrete wall presented remarkable resistance against internal forces, which is significantly superior to that of the other two diaphragm wall types. The aforementioned factors illustrate the promising potential of thermal modeling in the field of civil engineering relating to deep excavation projects.