Controlling jet grouting application using geotechnical methods: Example of Erciş (Van) Wastewater Treatment Plant

Jet grouting is one of the widely preferred methods for improving the physical and mechanical properties of soils with low strength and high deformation properties. Jet Grouting is based on the injection of varying proportions of water-cement grout at very high pressure (at least 300 bar) through very small diameter rotational nozzles into the ground. In this method, high-strength cylindrical jet grouting columns of various diameters are occupied by injection pressure and high-velocity of the jet fluid. These Jet Grouting columns, which are formed by stirring the soil, incorporate some soil material as well as cement. In addition, during injection of the high-presure fluid, when the columns are being formed, compression zone among the columns are formed due to squeezing of the soil around the columns. In this study, the improvement of the strength characteristics of soils with varying grain sizes in the compression zone around jet grouting columns was verified through field tests. Within the scope of this study, Standard Penetration Tests and Multi-channel Surface Wave Analysis Methods (MASW) were carried out in the field before Jet Grouting in order to estimate the soil characteristics. In consequence of the repeated tests applied on the soils located between the jet grouting columns, the variation of SPT blow-counts and S-wave velocities were determined in these compression zones. The results of the field tests indicate that the SPT blow-counts and S-wave velocities of the soils in the compression zone significantly increased compared to their initial values. This increase suggests that the soil between jet grouting columns is positively affected by the grouting pressures and resulted in a substantial improvement in its physical and mechanical properties.