Sun Yongshuai, Zhong Xinyan, Lv Jianguo, Wang Guihe
College of Water Resources & Civil Engineering, China Agricultural University, Beijing 100083, China.
School of Engineering and Technology, China University of Geosciences, Beijing 100083, China.
Microorganisms. 2023 Jan 20;11(2):281. doi: 10.3390/microorganisms11020281.
At present, in the field of geotechnical engineering and agricultural production, with increasingly serious pollution an environmentally friendly and efficient means is urgently needed to improve the soil mass. This paper mainly studied the microbial induced calcium carbonate precipitation (MICP) technology and the combined effect of MICP technology and lignin on the improvement of silt in the Beijing area. Through unconfined compressive strength and dynamic triaxial test methods, samples improved by microorganisms were studied to obtain the optimal values of cement concentration and lignin under these two test schemes. The results show that after the incubation time of reached 24 h, the OD600 value was 1.7-2.0 and the activity value (U) was 930-1000 mM ms/min. In the unconfined static pressure strength test, after MICP treatment the optimal concentration of cementitious solution for constant temperature and humidity samples and constant-temperature immersion samples was 1.25 mol/L. The compressive strength of the constant temperature and humidity sample was 1.73 MPa, and the compressive strength of the constant-temperature immersion sample was 3.62 Mpa. At the concentration of 1.25 mol/L of cement solution, MICP technology combined with lignin could improve the constant temperature and humidity silt sample. The optimal addition ratio of lignin was 4%, and its compressive strength was 1.9 MPa. The optimal lignin addition ratio of the sample soaked at a constant temperature was 3%, and the compressive strength was 4.84 MPa. In the dynamic triaxial multi-stage cyclic load test, the optimal concentration of cementation solution for the constant temperature and humidity sample after MICP treatment was 1.0 mol/L, and the failure was mainly inclined cracks. However, in the condition of joint improvement of MICP and lignin, the sample mainly had a drum-shaped deformation, the optimal lignin addition ratio was 4%, and the maximum axial load that the sample could bear was 306.08 N. When the axial dynamic load reached 300 N, the strain accumulation of the 4% group was only 2.3 mm. In this paper, lignin, an ecofriendly material, was introduced on the basis of MICP technology. According to the failure shape and relevant results of the sample, the addition of lignin was beneficial for the improvement of the compressive strength of the sample.
目前，在岩土工程和农业生产领域，随着污染日益严重，迫切需要一种环保高效的方法来改良土体。本文主要研究了微生物诱导碳酸钙沉淀（MICP）技术以及MICP技术与木质素联合作用对北京地区粉土的改良效果。通过无侧限抗压强度试验和动三轴试验方法，对微生物改良后的试样进行研究，得出这两种试验方案下水泥浓度和木质素的最优值。结果表明，培养24 h后，OD600值为1.7 - 2.0，活性值（U）为930 - 1000 mM ms/min。在无侧限静压强度试验中，经MICP处理后，恒温恒湿试样和恒温浸泡试样的最优胶结液浓度均为1.25 mol/L。恒温恒湿试样的抗压强度为1.73 MPa，恒温浸泡试样的抗压强度为3.62 MPa。在水泥溶液浓度为1.25 mol/L时，MICP技术与木质素联合作用可改良恒温恒湿粉土试样。木质素的最优添加比例为4%，其抗压强度为1.9 MPa。恒温浸泡试样的木质素最优添加比例为3%，抗压强度为4.84 MPa。在动三轴多级循环加载试验中，经MICP处理后，恒温恒湿试样的最优胶结液浓度为1.0 mol/L，破坏形式主要为斜向裂缝。然而，在MICP与木质素联合改良条件下，试样主要呈鼓形变形，木质素最优添加比例为4%，试样所能承受的最大轴向荷载为306.08 N。当轴向动荷载达到300 N时，4%组的应变累积仅为2.3 mm。本文在MICP技术的基础上引入了环保材料木质素。根据试样的破坏形态和相关结果，木质素的添加有利于提高试样的抗压强度。
