低pH值下微生物诱导碳酸盐沉淀加固尾矿砂试验研究  

Experimental study on reinforcement of tailings sand by microbially induced carbonate precipitation at low pH

作　　者：赖永明 俞缙[1] 刘士雨[1] 蔡燕燕[1] 涂兵雄[1] 刘谦[2] LAI Yong-ming;YU Jin;LIU Shi-yu;CAI Yan-yan;TU Bing-xiong;LIU Qian(College of Civil Engineering,Huaqiao University,Xiamen,Fujian 361021,China;College of Resource Engineering,Longyan University,Longyan,Fujian 364000,China)

机构地区：[1]华侨大学土木工程学院,福建厦门361021 [2]龙岩学院资源工程学院,福建龙岩364000

出　　处：《岩土力学》2024年第6期1583-1596,共14页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.52278351,No.52178334);福建省自然科学基金(No.2023J01963,No.2021J011085);龙岩市科技计划项目(No.2023LYF9001);新罗区产学研科技联合创新项目(No.2022XLXYY015);福厦泉国家自主创新示范区协同创新平台项目(No.3502ZCQXT2022002)。

摘　　要：开展低pH值下微生物诱导碳酸盐沉淀(microbially induced carbonate precipitation,简称MICP)加固尾矿砂试验,研究了菌液浓度、pH值对碳酸钙生成量和絮凝滞后期的影响。采用渗透性、保水性、抗雨滴侵蚀、抗风蚀、贯入度试验评价该方法加固尾矿砂效果。通过分析pH值对脲酶活性和碳酸盐体系平衡的影响,结合扫描电子显微镜和X射线衍射试验观察尾矿砂微观结构,揭示低pH值下MICP加固尾矿砂机制。结果表明,低pH值下MICP方法可以显著提高尾矿砂力学性能,一轮喷淋处理后尾矿砂的风蚀质量为0,渗透系数最大可降低一个数量级,pH值为4的高浓度菌液处理后的尾矿砂风雨侵蚀质量也为0。低pH值暂时抑制了脲酶活性,打破了碳酸盐体系的平衡,延缓了碳酸钙的生成,使得方解石均匀填充于粒间孔隙,将尾矿砂颗粒胶结为整体。提出的尾矿库加固及尾矿砂治理新技术及其加固机制,为低pH值下MICP加固尾矿砂应用提供了理论与试验依据。Experiments were conducted to investigate the effects of bacterial solution concentration and pH on calcium carbonate production and the bioflocculation lag period during microbially induced carbonate precipitation(MICP)reinforcement of tailings sand.The effectiveness of this method in reinforcing tailings sand was evaluated using tests for permeability,water retention,resistance to raindrop erosion,wind erosion resistance and penetration.By analyzing the influence of pH on urease activity and the equilibrium of the carbonate system,and observing the microstructure of tailings sand through scanning electron microscope and X-ray diffraction tests,the mechanism of MICP reinforcement of tailings sand at low pH was revealed.Results showed that the MICP method at low pH significantly improved the mechanical properties of tailings sand.After a single spray treatment,the wind erosion mass of tailings sand was reduced to zero,and the permeability coefficient decreased by an order of magnitude.Additionally,the raindrop and wind erosion mass of tailings sand treated with a high-concentration bacterial solution at pH=4 was also reduced to zero.Low pH temporarily inhibited urease activity and disrupted the carbonate system equilibrium,delaying calcium carbonate precipitation.This allowed calcite to uniformly fill the intergranular pores of tailings sand,cementing the sand particles together.This research presents a novel approach to tailings dam reinforcement and tailings sand treatment,elucidating its reinforcement mechanism and offering theoretical and experimental support for the application of low-pH MICP reinforcement of tailings sand.

关 键 词：低PH值 微生物诱导碳酸盐沉淀(MICP) 尾矿砂 脲酶活性 碳酸盐体系平衡 

分 类 号：TU411[建筑科学—岩土工程]