Biogeotechnics最新文献

Soil liquefaction is a major geo-hazard. As liquefaction could occur anywhere in a sand layer and result in large-scale lateral spreading, treatment for liquefaction needs to be carried out over a large extent. The cost-effectiveness of the treatment then becomes a major consideration. With the development of microbial geotechnologies, some new approaches for liquefaction mitigation have been developed. Some of the methods offer more advantages over the existing methods. This paper gives an overview of the recent progress in bio related soil liquefaction mitigation methods. These include both bio-cementation and biogas desaturation. The mechanisms of bio-cementation and biogas desaturation are discussed. Recent up-scaled model tests and field trials are also reviewed. The studies so far have demonstrated that there is a great potential for some of liquefaction mitigation methods to be adopted in practice, although there are still challenges that need to be studied further. These include treatment efficiency, long-term sustainability, and biosafety. A brief introduction to some emerging technologies for liquefaction mitigation such as bio-gelation and use of fungi are also introduced.

Enzyme-induced carbonate precipitation (EICP) is an environment-friendly method for improving soil mechanical properties. The extraction and application of plant crude urease reduces the treatment cost. However, in terms of the efficiency of calcium carbonate production and cementation, crude urease is considered inferior to pure urease or urease bacteria. In this paper, urease extracted from soybean was used to explore the effects of urease activity, treatment method, number of treatments (NTs), injection rate, and curing time on the unconfined compressive strength and calcium carbonate distribution characteristics of EICP-treated sand. The results showed that, compared with the pre-mixing method and the two-phase method, the one-phase method produced higher strength and a more uniform distribution of calcium carbonate. The cementation efficiency decreased with the increase of urease activity. The high-rate injection can improve the treatment effect of high-activity urease. Under the same cementation level, high strength and calcium carbonate cementation efficiency can be achieved by one-phase-low-activity EICP treatment.

Data Availability Statement

All data, models, and code generated or used during the study appear in the submitted article.

Geotechnical research has been yearning for revolutionary innovations that could bring breakthroughs to conventional practices, especially at a time when energy efficiency and environmental sustainability are of unprecedented importance in the field. Recently, exciting opportunities emerged utilising microorganisms, the ubiquitous soil dwellers, to provide solutions to many geotechnical problems, prompting the development of the new, multidisciplinary subject of biogeotechnics. Research interest has been centred on the use of microbially induced carbonate precipitation (MICP) to improve the engineering properties of soils. The present work aims to comprehensively review the progress of more than a decade of research on the application of MICP in soil strengthening. Through elucidation of underlying mechanisms, compilation and interpretation of experimental findings, and in-depth discussion on pivotal aspects, with reference made to key published studies, a holistic picture of the state of the art of MICP-based soil strengthening is drawn. Current knowledge gaps are identified, and suggestions for future research are given, along with the opportunities and challenges that lie ahead of practically implementing this technique in real-world geotechnical applications.