چكيده به لاتين
Specifications of soilcrete columns that are achieved from the jet grouting procedures from the diameter and strength aspect depend on jet grouting parameters such as grout pressure, lifting speed, number and diameter of nozzles and c/w ratio. In recent years, due to usage of this method in numerous projects, there is a need to conduct research that provide more accurate and comprehensive understanding of this method.
In this study, by constructing laboratory-scale columns, the effects of relative density (5% and 95%), soil moisture (0% and 20%), uplift rate (0.1 to 1 cm / s) and rod rotation frequency (10 and 25 rpm) on the resulting diameter are surveyed. Also, cores were taken from the columns and by uniaxial compression test, compressive strength changes of the columns were analyzed.
According to the results of this study, the highest column diameter was 11.7 cm at following conditions, 20% soil moisture content, 10 rpm rotation frequency, 5% relative density and 0.1 cm / s rod uplift rate. By increasing the rod uplift velocity from 0.1 to 1 cm /s, the efficiency coefficient which is equal to ratio of the unit column length volume to the energy consumed is increased. Therefore, although the maximum column diameter was obtained in the earlier conditions, but economic efficiency increased as the rod uplift speed increased.
Based on the findings of this study, soil density and rotational frequency were inversely related to either column diameter and efficiency coefficient. However, with increasing soil moisture, column diameter and efficiency coefficient increased. Also increasing the speed of rod uplift led to an increase in the efficiency coefficient and a decrease in column diameter. It should be noted that the earlier mentioned parameters had little effect on the change of column strength.
Keywords: Soil improvement, Laboratory jet grouting, Uniaxial compressive strength, Evaluation of column diameter, Influence of executive parameters and soil properties on column characteristics.
