软黏土中上覆荷载对注浆抬升长期效果影响的模型试验研究

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

利用注浆模型试验装置进行了一系列室内注浆试验,研究在不同上覆荷载条件下,软黏土中注浆抬升长期效果的变化规律,以及注浆间隔时间、土体超固结比和软黏土中加固措施对注浆抬升长期效果的影响。结果表明:正常固结土的最终补偿注浆率随上覆荷载的增大而减小,注浆峰值压力随上覆荷载的增大而增大,且与上覆荷载呈线性关系;总注浆量相同时,采用重复注浆方式时,上覆荷载较小时最终补偿注浆率小于连续注浆时最终补偿注浆率,上覆荷载较大时则大于连续注浆时最终补偿注浆率;相同上覆荷载条件下,重复注浆间隔时间越长,最终补偿注浆率越小;对超固结土,注浆抬升效果较好,最终补偿注浆率随超固结比的增大而增大,当上覆荷载大于75 k Pa或者超固结比增大到2.0后,最终补偿注浆率几乎不随上覆荷载的变化而变化;对软黏土进行预先加固后再进行抬升注浆,可显著提高其最终补偿注浆率,注浆抬升效果明显。

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 k Pa 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.