Investigation of dynamic behaviour of stabilized loose sand by microbially induced carbonate precipitation

Authors

1 Department of Civil Engineering, Qazvin Branch, Qazvin Islamic Azad University, Iran

2 Department of Civil Engineering, Qazvin Branch, Islamic Azad University, Qazvin, Iran

3 Department of Civil and Environmental Engineering, University of New Hampshire, USA and Department of Civil Engineering, Qazvin Branch, Islamic Azad University, Qazvin, Iran

Abstract

Due to the increasing number of construction projects, various methods, including more environmentally friendly methods, are used to increase the strength and bearing capacity of soil. Bio-cementation method is one of the newest methods that uses bacteria to form calcium carbonate crystals to make high-strength metamorphic products. This process can stabilize soil without breaking the original structure. In this research, the effect of microbially induced carbonate precipitation (MICP) on the cyclic properties (liquefaction resistance, secant shear modulus and damping ratio) of loose sand is investigated via performing cyclic triaxial tests. Results revealed that carbonate precipitation could significantly increase the liquefaction resistance of Kuhin sand. So that the required cycles to reach the liquefaction criteria was increased from 6 for unstabilized sand to 97 (at cyclic stress ratio (CSR) of 0.2) for 4 times grouted carbonate precipitated sand. Also, this value was increased to 127 for 6 times grouted carbonate precipitated sand. Moreover, test findings show that CSR has an important effect on liquefaction resistance such that, the number of cycles leading to liquefaction decreased from 127 to 46 with the increase of CSR from 0.2 to 0.3 for 6 times grouted carbonate precipitated sand. Due to the carbonate precipitation, the secant shear modulus of sand increased by up to 67%, and also the damping ratio of sand increased by up to 50%

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Journal of Civil and Environmental Engineering

Articles in Press, Accepted Manuscript
Available Online from 22 October 2022

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