包裹碎石桩加固的砂土液化机理试验研究

通过分别开展包裹碎石桩加固、碎石桩加固以及未加固的饱和砂土液化振动台试验,对比分析不同加固类型下的抗液化性能,重点剖析包裹碎石桩加固的砂土液化机理。试验表明:振动加载过程中,包裹碎石桩始终保持桩体的完整性与良好的排水性能且其加固模型地基的总沉降量相较于未加固模型地基减少了50%,相较于碎石桩加固模型地基减少了31.8%。包裹碎石桩加固模型排出水量较未加固模型地基提高了33.3%,较碎石桩加固模型地基提高了16.6%;包裹碎石桩加固模型地基的超静孔压值下降显著且地基下层砂土出现未液化的现象;并进一步发现包裹碎石桩的排水加固作用沿土层竖向深度呈递增趋势。因此,可以发现包裹碎石桩加固砂土液化的抗震性能优于碎石桩。

Experimental Study on the Liquefaction Mechanism of SandySoil Enforced by Geo-encased Stone Columns

Geo-encased stone columns are novel types of columns wrapped in layers of geosynthetics. They retain the excellent performance of stone columns and fully exploit the tensile properties of geosynthetics, which can improve the rigidity, shear resistance, and drainage effect of stone columns. However, few studies have focused on the liquefaction of sandy soil reinforced by geo-encased stone columns. In this work, shaking table tests on the liquefaction of sandy soil without reinforcement, reinforced with geosynthetic-encased stone columns, or reinforced with stone columns are carried out to investigate and compare the anti-liquefaction performances of the reinforcements. Results show that during vibration loading, the geo-encased stone columns consistently maintained their integrity and good drainage performance. Compared with those of the non-reinforced foundation and the foundation reinforced with stone columns, the total settlement values of the foundation reinforced with geosynthetic-encased stone columns decreased by 50% and 31.8%, respectively. Moreover, the amount of discharged water of the foundation reinforced with geosynthetic-encased stone columns increased by 33.3% and 16.6%, respectively, relative to those of the non-reinforced foundation and the foundation reinforced with stone columns. Excess pore water pressure in the foundation reinforced with geo-encased stone columns has drastically reduced, and sand liquefaction does not occur in lower portion of the foundation. The drainage performance of the foundation reinforced with geo-encased stone column tends to improve as the vertical depth of the soil increases. The seismic performance of geo-encased stone columns is better than that of stone columns.