Laboratory model tests on effect of overlying load on long-term effectiveness of grouting uplift in soft clay

A series of laboratory grouting tests are performed to study the change rules of the long-term effectiveness of grouting uplift under various overlying loads by using a set of grouting experimental setup. The effects of interval time, overconsolidation ratio and reinforcement measures of soft clay on the long-term efficiency of grouting uplift under various overlying loads are also studied. The results show that the final compensation grouting efficiency of normally consolidated soils decreases with the increase of overlying load. The peak grouting pressure increases linearly with the increase of overlying load. When the total grouting volume is the same and regrouting is conducted, the single injection with large injection volume results in the best final compensation grouting efficiency under small overlying load, whereas the final compensation grouting efficiency of single injection is less than that of regrouting under large overlying load. In addition, the larger the interval time, the lower the final compensation grouting efficiency when the overlying load is the same. For the over-consolidated soil, the efficiency of grouting uplift is significant and the final compensation grouting efficiency increases with the increase of over-consolidation ratio. The final compensation grouting efficiency almost has little change with the increase of the overlying load when the overlying load is larger than 75 kPa or the over-consolidation ratio is equal to 2.0. The reinforcement measures can significantly increase the final compensation grouting efficiency and the effect of grouting uplift is obvious.