饱和软黏土路基中布袋注浆桩的挤土效应

为研究饱和软黏土路基条件下布袋注浆桩的挤土效应，以布袋注浆桩加固某饱和软黏土路基工程为例，通过现场试验对桩体成型过程中的桩周土体位移和超静孔隙水压力进行了分析. 运用测斜管监测了成桩时桩周土体的水平位移，得到了土体位移的分布特征和土体位移随注浆压力与时间的变化规律；运用孔压计监测了成桩时桩周土体中超静孔隙水压力，得到了超静孔隙水压力的分布规律与变化趋势. 试验结果表明:成桩后，桩周土体水平位移呈现“马鞍形”分布，在距离地表0.1～0.3倍和0.8～1.0倍的桩长位置处出现最大位移；桩体成型挤土产生水平位移的范围约为桩径的6倍；桩体养护成型后，标准施工下的注浆压力对挤土效应的影响甚微，同时桩周土体水平位移会出现明显回弹，回弹位移值为注浆当天的40%～60%；超静孔隙水压力在前10 d消散较快，超静孔隙水压比随土体与桩体间距离的增加而呈现近似于线性规律的衰减，其影响范围约为10倍桩径. 

Soil Compaction Effect of Bagged Grouting Piles in Saturated Soft Clay Subgrade

To study the soil compaction effect of bagged grouting piles in saturated soft clay roadbeds, field tests were conducted on roadbeds reinforced with bagged grouting piles to analyse the displacement of the soil and the applied super-static pore pressure occurring during pile formation. First, the horizontal displacement of the soil was monitored by using the inclined pipe, and the distribution characteristics of soil displacement and variation in soil displacement with grouting pressure and time were obtained. Second, the super-static pore pressure in the soil was monitored by using a sensor to measure the hole pressure, and the distribution and trend of the super-static pore pressure were obtained. The test results indicate that the horizontal displacement of the soil around the pile has a saddle-shaped distribution, and the soil exhibits maximum displacement at a distance of 0.1–0.3 times and 0.8–1.0 times the pile length. The range of influence of the horizontal displacement caused by soil compaction is approximately six times the pile diameter. After the pile has been cured, the grouting pressure has little influence on the compaction effect. Furthermore, after curing, the horizontal displacement of the soil around the pile shows a significant rebound, which amounts to approximately 40%–60% of the displacement on the day of grouting. The super-static pore pressure dissipates rapidly during the first 10 days and decreases linearly with increasing distance from the centre of the pile. The range of influence of the super-static pore pressure is approximately 10 times the pile diameter.