Abstract: There was no systematic study on the development law of soil deformation and excess pore pressure caused by multi row hole grouting in soft soil area to date, which limits the deepening development of active control strategy of grouting deformation. In this study, field tests of multi-row grouting were carried out to systematically examine the variation and superposition law of soil horizontal displacement and excess pore pressure caused by single-row hole-by-hole grouting and multi-row row-by-row grouting. The research shows that the excess pore pressure caused by grouting decreases rapidly with distance, and the variation law can be expressed by a power function. It is recommended that the grouting is about 3 m or closer to the object. At this time, the grouting correction effect is the best. The excess pore pressure caused by grouting dissipated rapidly in Tianjin, which is conducive to the rapid stability of the deformation controlled by grouting. The dissipation law of excess pore pressure over time can be expressed by an exponential function, and an empirical formula for calculating excess pore pressure caused by grouting is put forward. When multiple rows of holes are grouted row by row, the wall formed by prior grouting has reaction force effect and shielding effect on the soil deformation on one side and the other side of the subsequent grouting respectively. When controlling the deformation of existing buildings and structures, the principle of “far before near” row by row grouting shall be followed so as to improve the effect of deformation control.

Key words: grouting method, soil deformation, in situ test, excess pore water pressure, multi-row grouting