Estimation of jet grouting parameters in Shahriar dam, Iran

Jet grouting is a method for improving of soil and its physical characteristics. However, in this method, grouting of cement slurry with high pressure and velocity may cause damaging to soil structure, and then excavated grains of soil are removed from the borehole and replaced with cement slurry. The grains, which are remained around the borehole, mixed with slurry (cement) in-situ, can create an improved mass of soil. This mass is named “Soilcrete”. Soilcrete mass has special characteristics such as high strength, low deformability and very low permeability. In this paper, principles of jet grouting and effective parameters have been analyzed. Then the test results obtained from Soilcrete column have been investigated. Finally, the paper concludes with presenting amount of principle jet grouting parameters at foundation of Shahriar dam according to the results of jet grouting test. Based on the measurements, the diameter, Soilcrete UCS (uniaxial compression strength), amount of the water, grout and air pressure and lifting and rotating speed in original site of jet grouting are 1.2∼1.5 m, 2∼3 MPa, 370∼390 bar, 10∼15 bar, 6∼8 bar, 7∼8 cm/min and 7∼8 cm/min, respectively. Also it can be seen that while the column diameter falls within the upper half of the range, some values of the compressive strength are close to the lower limit of the range.