Large diameter bored pile with grout injection (post-grouting)
1., 2. & 3. In accordance with the installation process of the large diameter bored pile with temporary casing or the large diameter bored pile under thixotropic fluid whereby the base and / or the shaft is / are injected with cement grout after completion of the pile, in order to increase its ultimate capacity (base resistance and / or shaft friction).
4. For that purpose, attached to the outer side (exterior) of the reinforcement cage are vertical steel injection pipes, the so-called ‘tubes à manchettes’ or TaM, perforated at regular intervals with grouting orifices (holes), covered by rubber sleeves (manchettes), allowing grout passage towards the surrounding soil but preventing its flow back in the tube After the installation of the pipe network, sleeve grout is added (put) in the hole.
5. The « TaM » are blasted under water pressure (“claquage”) within 24 hours after the concreting phase of the bored pile and injected according to the specific injection procedure. During the « claquage » or impregnation phase, the cement grout subsequently bursts / breaks the sleeve grout at the location of the ‘manchettes’ in order penetrate the soil.
The criteria for the termination of the injection phase (grout volume or injection pressure) are thus determined so that fracturing and decompression of the soil are avoided.