Some major projects, including big diameter jet grouting columns have been carried out during the last years in Spain. Based on the data obtained from the execution and result controls implemented during those jobs, an empirical method to estimate the column diameter that can be obtained with the high energy double fluid jet grouting is presented in this paper. This empirical method is based on the specific energy recorded during the jet grouting drilling phase (the drilling energy per meter of column) and on the specific energy recorded during the grouting phase (the grouting energy per cubic meter of treated ground). The column diameters used to calibrate the proposed method were obtained by visual inspection and by indirect techniques such as geophysics (resistivity) when that inspection was not possible. Additionally, some jet grouting columns were re-drilled with a drill rig with a drilling parameter recording system attached to it, in order to make a comparison between the recorded parameters and those recorded during the execution of the same jet grouting columns. By doing this at different distances from the column centres it was possible to assess the jet grouting column diameter. Finally and based on the results of this calibration, a step by step procedure is given to apply the proposed method to estimate the jet grouting column diameter in terms of the drilling and grouting specific energies.
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