An adjustable bio-sealing method for rock fracture leakage mitigation  

作　　者：Zhihao Dong Xiaohua Pan Chaosheng Tang Chao Lv Bin Shi 

机构地区：[1]School of Earth Sciences and Engineering,Nanjing University,Nanjing,210023,China [2]State Key Laboratory for GeoMechanics and Deep Underground Engineering,China University of Mining and Technology,Xuzhou,221116,China

出　　处：《Journal of Rock Mechanics and Geotechnical Engineering》2025年第1期220-232,共13页岩石力学与岩土工程学报(英文)

基　　金：supported by the National Natural Science Foundation of China(Grant No.41925012);Key task project for joint research and development of the Yangtze River Delta Science and Technology Innovation Community(Grant No.2022CSJGG1200);State Key Laboratory for GeoMechanics and Deep Underground Engineering(Grant No.SKLGDUEK2214).

摘　　要：This study proposed a repeated adjustable mixture injection strategy(RAM)based microbial induced carbonate precipitation(MICP)for efficient mitigation of rock fracture leakage.Granite fractures with small apertures were investigated,and bio-sealing experiments were conducted using five different cementation solution(CS)concentrations(0.25−2 M).The results showed that the RAM-based bio-sealing method can seal and bond the small aperture rock fractures with high efficiency and uniform precipitation by adjusting the CS concentration.The RAM-based bio-sealing mechanism is attributed to the following four stages:(1)fixation of bacterial flocs onto the fracture surfaces,(2)precipitation of CaCO3 onto the fracture surfaces,(3)growth of pre-precipitated CaCO3 and adhesion of new-suspended CaCO3,and(4)bridging and clogging processes.The optimal CS concentration of 1 M resulted in a fracture filling rate up to 85%,a transmissivity reduction of 4 orders of magnitude,and a shear strength ranging from 512 kPa to 688 kPa.The bio-sealing effect was found to be influenced by the CS concentration on bacterial attachment,calcium carbonate yield and calcium carbonate bulk density.The CS concentration of 1 M promoted bacterial attachment,and increased calcium carbonate yield as well as calcium carbonate bulk density,while concentrations above 1 M had the opposite effect.The bulk density of calcium carbonate played a crucial role in the sealing and bonding performance of bio-sealed fractures,particularly at comparable filling ratios and bridging areas.The bulk density was regulated by the size of calcium carbonate crystals and was determined by Ca2+concentration in the CS.This study provides valuable insights into the RAM-based bio-sealing method,highlighting its potential for efficient rock fracture leakage mitigation through precise control of CS concentration and understanding the underlying mechanisms.

关 键 词：MICP Rock fracture Hydraulic and mechanical performance Bio-sealing 

分 类 号：TU452[建筑科学—岩土工程]