A study on the enhancement of the mechanical properties of weak structural planes based on microbiologically induced cal
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ORIGINAL PAPER
A study on the enhancement of the mechanical properties of weak structural planes based on microbiologically induced calcium carbonate precipitation Dong Liu 1 & Anlin Shao 2 & Hao Li 1 & Changyu Jin 2 & Yunlong Li 1 Received: 25 August 2019 / Accepted: 24 April 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The advantages of outstanding economic efficiency and green environmental protection have positioned microbially induced technologies among the most promising reinforcement methods for structural planes. In this work, the enhanced mechanical properties of a weak structural plane at Baihetan Hydropower Station in China are investigated after microbially induced calcium carbonate precipitation. Sporosarcina pasteurii is actively cultured, and a standard curve relating bacteria concentration and optical density is developed. The curves of bacterial growth and urease activity are then investigated. Microbial reinforcement of weak structural plane specimens is conducted. The mechanical properties of weak structural planes are tested after reinforcement, and effects of bacteria concentration on the uniaxial compressive, shear, and triaxial compressive strengths are discussed. Based on XRD, EDS, and SEM analyses, the product of the microbially induced process is found to be calcium carbonate crystals, which measure approximately 5~10 μm. It is observed that the crystals are well grown and distributed around particles in the weak interlayers. These particles are gradually encapsulated by induced crystals and finally cemented with interfaces of the tuff. The results also reveal that maximum increments of 148, 130, 192, and 114% of the uniaxial compressive strength, triaxial compressive strength, cohesion, and friction angle of the rock mass, respectively, can be obtained by adopting the microbially induced reinforcement method. It is expected that this paper can provide theoretical support for the reinforcement of structural planes of rock masses via ecologically green methods that save energy and reduce emissions. Keywords Rock mass . Weak structural plane . Microbial . Reinforcement . Calcium carbonate
Introduction Weak structural planes are gradually formed and extended in natural rock masses over time. Based on the large number of geological engineering accidents, the integrity and mechanical properties of rock masses are greatly weakened by weak structural planes, leading to sidewall cracking, dislocation of upper and lower rock masses, roof arch collapsing, landslides, etc.
Based on the statistical data from the International Consortium on Landslides (ICL) Association, in the period of 1974–2003, shown in Fig. 1, disastrous landslide accidents induced by the deformation and failure of the structural planes of rock masses are globally distributed. To solve engineering problems of geological accidents induced by weak structural planes of rock masses, global geotechnical researchers devoted to study reinforcement methods
* Yunlong Li [email protected]
Changyu Jin jc
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