Abstract:
The process of cement column installation by jet grouting techniques is composed of
high pressure water injection and cement slurry jet water high pressure, sequentially,
into the ground. This process has effects on surrounding soils and nearby structures.
Many previous researches identified that the excess pore water pressure generating
during the installation is one of the key factors. Thus, in this study, the excess pore
water pressure rising-dissipation due to installation of cement column in soft clay was
investigated to get better understanding of such behavior. The interaction with the
surrounding clay in ternl of rising of excess pore water pressure during installation can
be simulated as the expanding process of a cylindrical cavity theory. The excess pore
water pressure was expressed in terms of undrained strength of clay, injection pressure,
and a pore water pressure parameter. The dissipation of excess pore water pressure was
simulated by solving governing equations for the radial consolidation of the soil around
a cement column. A convenient method for this solution was offered by technique of
finite differences. The applied superposition method was proposed for the prediction of
the rising-dissipation of excess pore water pressure following installation of
multicolumn. With the combination of the aforementioned approach, the excess pore
water pressure rising and dissipation during multicolumn installations can be reasonably
simulated. Moreover, all necessary features, which are influences of distance, time
interval and injection pressure can be captured. The predicting results were verified
against laboratory model test and in situ cement column installation in clay ground. The
prediction values are in fair agreement with the observed excess pore water pressure in
laboratory model test.