颗粒级配对微生物固化砂土力学性能的影响

土体的颗粒级配不同，其微生物固化效果也可能存在一定的差别。将颗粒粒径范围为0.074~2.000 mm的砂土分成颗粒级配良好与颗粒级配不良4组，分别测试了固化后砂样的无侧限抗压强度、渗透系数、孔隙率，碳酸钙沉淀量，从宏观角度对比了颗粒级配对微生物固化砂土的物理力学性质影响。同时，结合电镜扫描，从微观角度分析了颗粒级配对微生物固化砂土的影响机制。研究结果表明：相比于颗粒级配不良的砂土，颗粒级配良好的砂土碳酸钙沉淀量与均匀性更好，孔隙率与渗透系数更小，从而增加了试样的无侧限抗压强度。这是因为级配良好的砂土自身含有更优的粗细颗粒组，可提供更多有利于生成碳酸钙的沉积位置，生成的碳酸钙更加致密，强度更高。

Influence of particle gradation on mechanical properties of MICP-treated sand

The particle gradation of soil is different, and the MICP-treated effect may be different. In this paper，the sand with particle size range of 0.074-2.0 mm was divided into four groups with good particle gradation and poor particle gradation. The unconfined compressive strength, permeability coefficient, porosity, calcium carbonate precipitation of the sand samples after curing were tested respectively. So the effects of particle gradation on mechanical properties of MICP-treated sand were compared from the macroscopic point of view. At the same time, combined with electron microscope scanning, the influence mechanism was analyzed from the microscopic point of view. The results showed that the sand of good particle gradation is better than the sand of poor particle gradation, because its amount and uniformity of calcium carbonate precipitation is better, and the porosity and permeability coefficient are smaller, thus increasing the unconfined compressive strength of the sample. This can be explained that the well-graded sand contains a better group of coarse and fine particles, which can provide more favorable deposition sites for calcium carbonate, and the silting calcium carbonate is denser and stronger.