MICP restoration law of coal mining induced ground fissures and its influencing factors

Authors

LI Tao, School of Mining and Mechanical Engineering, Liupanshui Normal University, Liupanshui 553004, China; College of Geology and Environment, Xi’an University of Science and Technology, Xi’an 710065, China; College of Resource and Environmental Engineering, Guizhou University, Guiyang 550025, ChinaFollow
GAO Ying, School of Mining and Mechanical Engineering, Liupanshui Normal University, Liupanshui 553004, China
YAN Jingwang, Shenmu Ningtiaota Mining Co., Ltd. of Shaanxi Coal Group, Shenmu 719300, China
ZHANG Jiarui, College of Geology and Environment, Xi’an University of Science and Technology, Xi’an 710065, China
KOU Guigui, Shenmu Ningtiaota Mining Co., Ltd. of Shaanxi Coal Group, Shenmu 719300, China
MA Tengfei, School of Mining and Mechanical Engineering, Liupanshui Normal University, Liupanshui 553004, China
MEI Aoran, College of Resource and Environmental Engineering, Guizhou University, Guiyang 550025, China

Abstract

The coal mining induced ground fissures in the loess covered area of northwest China cause shallow groundwater resource leakage and soil instability. Therefore, the experimental study was conducted on Microbial Induced Carbonate Precipitation (MICP) restoration of coal mining induced ground fissures in the loess covered area. Specifically, the characteristics of mining induced ground fissures were observed and their development characteristics were revealed based on Ningtiaota Coal Mine in northern Shaanxi. The coal mining induced ground fissures in loess were classified with consideration to the observed mine pressure. Based on the classification and characteristics of coal mining induced ground fractures, the mechanical and hydraulic parameters of two types of MICP-treated loess fissure samples were compared and tested using the unconfined compression tests, triaxial compression tests, variable head permeability tests and triaxial permeability tests. In addition, the influencing factors of MICP restoration for coal mining induced ground fissures were analyzed based on the pH value of the restoration body, MICP calcium carbonate production, and scanning electron microscopy test results. The results indicate that coal mining induced ground fissures in loess covered areas can be divided into two types: boundary ground fissures and internal ground fissures. In terms of boundary ground fissures, the optimal ratio of bacterial solution to cementitious fluid is 1.2∶1.0. For the internal ground fissures, the optimal ratio of wind-blown sand and loess to fill the fissures is 1∶1, and the optimal ratio of bacterial solution and cementitious fluid is 1∶1. The difference in the opening of different types of coal mining induced ground fissures in loess covered areas results in a 31.2% difference in the yield of calcium carbonate. Therefore, the optimal MICP restoration solution for boundary ground fissures has a larger proportion of cementitious fluid compared to internal ground fissures. When the ratio of wind-blown sand and loess in the filling material is 1∶1, the pH value of the mixture of filling material and restoration fluid is 9.2, and the yield of calcium carbonate in such pH value environment can reach 88%, promoting the efficient operation of MICP. The research results provide a reference for the restoration of coal mining induced ground fissures in loess covered areas.

Keywords

coal mining, loess, ground fissures, microbial induced carbonate precipitation (MICP), physical property

DOI

10.12363/issn.1001-1986.23.04.0200

Recommended Citation

LI Tao, GAO Ying, YAN Jingwang, et al. (2023) "MICP restoration law of coal mining induced ground fissures and its influencing factors," Coal Geology & Exploration: Vol. 51: Iss. 11, Article 12.
DOI: 10.12363/issn.1001-1986.23.04.0200
Available at: https://cge.researchcommons.org/journal/vol51/iss11/12

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