MICP技术改性膨胀土试验研究

Experimental Study on Modifying Expansive Soil by MICP Technology

为了探究膨胀土新型改良技术,引进微生物诱导碳酸钙沉淀(MICP)新型环保的土体加固技术,利用巴氏芽孢八叠球菌开展MICP压力灌浆改性膨胀土室内试验,研究了胶结液浓度对膨胀土力学性能、微观结构及水理特性的影响,揭示了MICP技术改性膨胀土的作用机理,评价了MICP压力灌浆改性膨胀土试验的效果。试验结果表明:灌浆处理后试样的无侧限抗压强度最大增加了379.4%,土体刚度也有所提高;试样的膨胀性、渗透性均有明显改善,膨胀力最高可减少25.3 kPa,渗透系数最大减少3个数量级;试验改性效果随着胶结液浓度的增大而提高,但当胶结液浓度增大到一定程度后,改性效果不再显著。研究成果验证了MICP技术用于改性膨胀土的有效性和可行性。

Microbial induced calcium carbonate precipitation is a new kind of environmental-friendly soil reinforcement technology.Through laboratory MICP grouting test of expansive soil modification using Sporosarcina pasteurii,we investigated into the influences of cementing fluid concentration on the mechanical properties,microstructure and hydraulic characteristics of expansive soil.Moreover,we also revealed the mechanism and effect of modifying expansive soil by MICP technology.Test results demonstrate that MICP is effective in modifying expansive soil.After grouting,the unconfined compressive strength of soil samples increased by 379.4%at most,and the stiffness of soil was also improved.The expansibility and permeability of the samples reduced by up to 25.3 kPa and by three orders of magnitude,respectively.The modification effect ameliorated with the increase of cement concentration;but when the cement concentration reached a certain extent,the modification effect was no longer significant.The research findings verified the effectiveness and feasibility of MICP technology in modifying expansive soil.