菱镁矿尾矿粉联合EICP加固粉土的试验研究  

Experimental study on reinforcement of silt by magnesite tailings powder combined with EICP

作　　者：原华[1] 丁仕兵 朱紫琪 左可成 韩智光 朱想 YUAN Hua;DING Shibing;ZHU Ziqi;ZUO Kecheng;HAN Zhiguang;ZHU Xiang(School of Civil Engineering and Architecture,Henan University,Kaifeng 475004,China)

机构地区：[1]河南大学建筑工程学院,开封475004

出　　处：《中国有色金属学报》2025年第4期1429-1440,共12页The Chinese Journal of Nonferrous Metals

基　　金：国家自然科学基金资助项目(42177454);河南省2022年本科高校研究性教学改革研究与实践项目(2022SYJXLX010);河南省研究生教育改革与质量提升工程项目(YJS2025XQLH37)。

摘　　要：提出利用废弃菱镁矿尾矿粉联合脲酶诱导碳酸盐沉淀(EICP)胶结粉土的方法,通过试样尺度的宏观测试和基于扫描电子显微镜、X射线衍射的微观测试,分析菱镁矿尾矿粉掺量和固化时间对固化土体力学性能、成分组成、微观结构的影响,以及菱镁矿尾矿粉联合EICP固化粉土的机理。结果表明:与常规EICP相比,菱镁矿尾矿粉联合EICP处理粉土的无侧限抗压强度、黏聚力、内摩擦角和碳酸钙含量,分别提高了14.22%~56.86%、27.42%~59.68%、0.882%~10.29%和6.79%~14.71%。当菱镁尾矿粉的掺量为12%时,被固化粉土具有较好的强度、刚度和韧性以及较高的碳酸钙含量,故粉土中菱镁矿尾矿粉的掺量宜为12%;土体强度的提高,不仅仅与碳酸钙含量的增大有关,还与所沉淀碳酸钙晶体结构的优化有关。掺入菱镁矿尾矿粉后,除常规EICP过程中的化学反应外,Ca^(2+)与MgCO_(3)反应析出CaCO_(3)和Mg^(2+),碳酸钙沉淀量和沉淀率增大;且Mg^(2+)促使碳酸钙主要以文石和方解石晶型形式存在,增强了固化土体的力学性能。Utilizing waste magnesite tailings powder in combination with urease-induced carbonate precipitation(EICP)was proposed to consolidate silt.Macroscopic tests at the sample scale and microscopic analyses using scanning electron microscopy(SEM)and X-ray diffraction(XRD)were conducted to investigate the effects of magnesite tailings powder content and curing time on the mechanical properties,composition,and microstructure of the solidified soil,as well as the mechanism by which magnesite tailings powder enhances EICP-mediated silt consolidation.The results indicate that,compared with conventional EICP treatment,the unconfined compressive strength,cohesion,internal friction angle,and calcium carbonate content of silt treated with magnesite tailings powder combined with EICP increased by 14.22%-56.86%,27.42%-59.68%,0.882%-10.29%,and 6.79%-14.71%,respectively.When the content of magnesite tailings powder is 12%,the solidified silt has optimal strength,stiffness,toughness and high calcium carbonate content.Therefore,the recommended magnesite tailings powder content in silt should be 12%.The improvement in soil strength is not only related to the increased calcium carbonate content,but also closely relate to the optimization of calcium carbonate crystal structure precipitated inside the silt.Upon addition of magnesite tailings powder,in addition to the chemical reactions typical of conventional EICP,Ca^(2+)reacts with MgCO_(3) to precipitate CaCO_(3) and release Mg^(2+),thereby increasing both the quantity and proportion of calcium carbonate precipitation.Moreover,Mg^(2+)promotes a higher proportion of calcium carbonate to crystallize as aragonite and calcite,enhancing the mechanical properties of the solidified soil.

关 键 词：菱镁矿尾矿粉 粉土 脲酶诱导碳酸盐沉淀 固化效果 晶体结构 微观机制 

分 类 号：TU472[建筑科学—结构工程]