Experimental Study on the Influence of Microbial Content on Engineering Characteristics of Improved Expansive Soil

Ouyang, Qianwen; Xiao, Hongbin; Li, Zhenyu; Jiang, Weichang; Su, Huanyu; Tian, Xuwen; Ouyang, Mi

doi:10.3389/feart.2022.863357

Cited by 10 publications

(4 citation statements)

References 38 publications

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“…However, actinomycetes have not played a role in improving the cohesion of expansive soils [174]. Microbially induced calcite precipitation (MICP) has attracted more attention as a new soil modification method, as the swelling-shrinkage, compressibility, hydrophilicity, and soil strength of expansive soils can be improved using this technology [176][177][178][179]. Nevertheless, research is still needed regarding the required nutrition of strains in engineering applications and the long-term effects of soil modification.…”

Section: Biological Modification Methodsmentioning

confidence: 99%

Failure Mechanisms and Protection Measures for Expansive Soil Slopes: A Review

Luo,

2024

Sustainability

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Due to the significant hydrophilicity and cracking properties of expansive soils, expansive soil slopes are prone to destabilization and landslides after rainfall, seriously threatening the safety of buildings, highways, and railroads. Substantial economic losses often accompany the occurrence of expansive soil slope disasters; thus, it is of great significance to understand the slope failure mechanisms experienced by expansive soil slopes and to prevent expansive soil slope disasters. In this paper, the current research status of the landslide failure mechanism of expansive soil slopes is systematically reviewed based on three research methods: field test, model test, and numerical simulation. The failure mechanisms of expansive soil slopes and the main influencing factors are summarized. Based on the failure mechanisms, three protection principles (waterproofing and water blocking, swelling–shrinkage deformation limitation, and crack inhibition and strength enhancement) that can be followed for disaster prevention of expansive soil slopes are proposed. The research status and advantages and disadvantages of these protection methods are reviewed, and future researchable directions of the stability of expansive soil slopes and slope protection methods are explored. Based on the previous work, a new flexible ecological slope protection system with a double waterproof layer is proposed for expansive soil slopes to realize ecological, efficient, and long-term protection. This paper thus aims to provide technical reference for the prevention and control of slope engineering disasters in expansive soil areas.

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Section: Biological Modification Methodsmentioning

confidence: 99%

Failure Mechanisms and Protection Measures for Expansive Soil Slopes: A Review

Luo,

2024

Sustainability

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“…The experimental study of using microorganisms to improve unfavorable soil makes it possible to apply this method to engineering. Scholars have used MICP technology to improve unfavorable soil to varying degrees, including sand [ 40 , 41 , 42 ], silt [ 43 , 44 , 45 ], loess [ 46 , 47 , 48 , 49 , 50 ], expansive soil [ 51 , 52 , 53 , 54 ], and mucky soil [ 55 , 56 ], using this method, and the unconfined compressive strength and cohesion of the soil are significantly improved, which can be used in engineering practice. In the field of geotechnical engineering, the research results of MICP on soil improvement can be used for foundation reinforcement [ 57 , 58 , 59 ], earth dam reinforcement [ 60 ], wind prevention, sand fixation [ 61 ], reservoir bottom anti-seepage, and anti-seepage curtains [ 42 ].…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on Silt Soil Improved by Microbial Solidification with the Use of Lignin

Sun

Zhong

et al. 2023

Microorganisms

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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 Sporosarcina pasteurii 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.

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“…The carbonate ions combine with calcium ions in the soil to form calcium carbonate precipitates adsorbed on the surface of the bacteria (Liu et al, 2017). Relevant literature have shown that the MICP method can effectively reduce the expansion and contraction of expansive soils (Tiwari et al, 2021;Li et al, 2021) and improve their strength (Jiang et al, 2021;Ouyang et al, 2022). However, most of the studies on the improvement of expansive soils using the MICP method have focused on the physical properties, strength properties, and deformation properties of the improved expansive soils under short-term loading.…”

Section: Introductionmentioning

confidence: 99%

A Fractional Order Creep Damage Model for Microbially Improved Expansive Soils

Tian

Xiao

et al. 2022

Front. Earth Sci.

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Microbial Induced Calcite Precipitation method was used to improve the expansive soils of Nanning, Guangxi. The nonlinear shear creep behavior of microbially improved expansive soil was studied by triaxial consolidation drainage shear test. The results show that when the expansive soil was applied a small partial stress, the creep curve of soil exhibits transient deformation and decay creep. When the partial stress reaches a certain value, there is decay creep, steady-state creep and accelerated creep successively showed on the creep curve. The stress-strain isochronous curves reflect there are obvious nonlinear characteristics in the creep process of improved expansive soils. The degree of this nonlinearity is related to the creep time and stress level. The longer the creep time as well as the higher the stress level, the higher the degree of nonlinearity. Based on the fractional calculus theory and statistical damage theory, the probability density function of Weibull distribution was introduced, and the damage degradation of soft component viscosity coefficient was considered. As a result, a fractional-order damage creep model which can describe the shear creep evolution of microbially improved expansive soils is established. Compared with the Kelvin creep model of integer order and the Burgers creep model of fractional order, the fractional order damage creep model has not only better comparative evaluation results but also more higher computational accuracy. It indicates that the fractional-order damage creep model can better describe the whole process of shear creep in microbially improved expansive soils. The above findings provide a theoretical basis for the study of deformation analysis of microbially improved expansive soils under long-term loading.

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Experimental Study on the Influence of Microbial Content on Engineering Characteristics of Improved Expansive Soil

Cited by 10 publications

References 38 publications

Failure Mechanisms and Protection Measures for Expansive Soil Slopes: A Review

Failure Mechanisms and Protection Measures for Expansive Soil Slopes: A Review

Experimental Study on Silt Soil Improved by Microbial Solidification with the Use of Lignin

A Fractional Order Creep Damage Model for Microbially Improved Expansive Soils

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