Effects of activated carbon on liquefaction resistance of calcareous sand treated with microbially induced calcium carbonate precipitation
Effects of activated carbon on liquefaction resistance of calcareous sand treated with microbially induced calcium carbonate precipitation
复制标题
活性炭对微生物诱导碳酸钙沉淀处理钙质砂抗液化性能的影响
DOI：
10.1016/j.soildyn.2022.107419
复制
发表时间：
2022-07-19
影响因子：
4
通讯作者：
Li, Yuanyuan
中科院分区：
文献类型：
--
作者：
Shan, Yi;Zhao, Jitong;Li, Yuanyuan
微生物诱导碳酸钙沉淀法（Microbially induced CaCO_3 Decomposition，MICP）是一种新型的、天然的、环保的地基处理方法，可以提高钙质砂地基的抗渗能力。在地震或海浪等事件引起的动态载荷下，容易发生液化。活性炭是一种多孔物质，也提供吸附性能。本研究利用活性炭的吸附能力，提高微生物絮凝沉淀处理过程中细菌的截留率。通过细菌滞留试验、动三轴试验和微观扫描试验，研究了活性炭含量（相对于砂重为0%、0.25%、0.75%、0.50%、1.00%和1.25%）对经MICP处理的钙质砂抗液化性能的影响。结果表明，随着活性炭掺量的增加，试件累积阶段超静孔隙水压力循环次数增加，轴向应变幅值减小。随着活性炭含量的增加，细菌截留率，循环强度，和割线模量的样品被发现大大提高。在检查显微镜扫描图像时，观察到过量的活性炭在砂粒之间的分布导致其占据细菌成核位点并对砂粒之间的连接造成障碍。活性炭添加量为0.75%时，钙质砂的抗液化性能最好。研究结果表明，微生物对钙质砂的加固作用有利于提高钙质砂的微生物滞留率和抗液化能力。
Microbially induced calcium carbonate precipitation (MICP) is a new, natural, environmentally friendly treat-ment method for soil foundations, which can improve the resistance of calcareous sand foundations to lique-faction. Liquefaction is prone to occur under dynamic loading caused by events such as earthquakes or sea waves. Activated carbon is a porous substance that also offers the property of adsorption. In this study, the adsorption capacity of activated carbon was used to improve the retention ratio of bacteria during MICP treatment. Bacterial retention tests, cyclic triaxial (CTX) tests, and microscopic scanning tests were carried out to investigate the effects of variable activated carbon contents (namely 0%, 0.25%, 0.75%, 0.50%, 1.00%, and 1.25%, relative to the weight of the sand) on the liquefaction resistance of MICP-treated calcareous sand. The results showed that with the increasing activated carbon, the number of cycles of excess pore water pressure in the cumulative stage of the samples was increased, and the amplitude of axial strain was decreased. As the activated carbon content was increased, the bacterial retention ratio, cyclic strength, and secant modulus of the samples were found to improve considerably. On examination of microscopic scanning images, it was observed that the distribution of excessive activated carbon between the sand particles had resulted in it occupying the bacterial nucleation site and creating an obstacle to the connection between sand particles. The test using 0.75% activated carbon content best enhanced the resistance to liquefaction of calcareous sand. The outcome of this study may in the authors' view prove beneficial in improving the bacterial retention ratio and liquefaction resistance of calcareous sand when it is reinforced by microorganisms.