A field trial of horizontal jet grouting using the composite-pipe method in the soft deposits of Shanghai

A new horizontal jet grouting technique named the ‘Composite-Pipe Method’ has been developed to eliminate the adverse environmental impacts caused by construction. This paper introduces the construction equipment and construction procedure of the composite-pipe method. A field test was conducted with the construction of columns using both the composite-pipe method and the horizontal chemical churning pile (H-CCP) method (i.e. the traditional single fluid method). Field measurements were carried out on the vertical displacement of the ground surface, the diameter of the jet-grout column and the unconfined compressive strength (USC) of borehole samples from the soilcrete extracted from the jet grouted columns. The measurements of the vertical displacement of the ground surface indicate that the impact induced by the composite-pipe method is much smaller than that induced by the H-CCP method. A comparison of ground surface displacement between predicted values using Chai’s method and measured values indicates that Chai’s method can be applicable to the prediction of the ground surface displacement in the field by considering the volume of discharged spoil.

► We presented a new construction method for jet-grouting horizontally to reduce the effect on surroundings. ► We measured the responses of surrounding ground during conduction of horizontal jet grouting. ► We predicted vertical displacement using the method based on the cavity expansion theory. ► The proposed method can reduce the vertical displacement effectively compared with the traditional H-CCP method.