微生物诱导固结疏浚底泥填料路用力学性能  

Mechanical Properties of Microbial-induced Calcite Precipitation-improved Dredged Sediment as Road Subgrade Filling Material

作　　者：方明镜 林芝阳 党云 刘政伟 易毅 姚永胜 FANG Ming-jing;LIN Zhi-yang;DANG yun;LIU Zheng-wei;YI Yi;YAO Yong-sheng(School of Civil Engineering and Architecture,Wuhan University of Technology,Wuhan 430074,Hubei,China;Hubei Provincial Communications Planning and Design Institute Co.Ltd.,Wuhan 430051,Hubei,China;College of Traffic&Transportation,Chongqing Jiaotong University,Chongqing 400074,China)

机构地区：[1]武汉理工大学土木工程与建筑学院,湖北武汉430074 [2]湖北省交通规划设计院股份有限公司,湖北武汉430051 [3]重庆交通大学交通运输学院,重庆400074

出　　处：《中国公路学报》2024年第7期100-111,共12页China Journal of Highway and Transport

基　　金：湖北省交通运输厅科技项目(2020-186-1-3);2021年度交通运输行业重点科技清单项目(2021-MS5-127)。

摘　　要：为探究基于微生物诱导碳酸钙沉淀(MICP)的疏浚底泥路基填料改良过程优化与路用性能提升可行性,采用混拌法对疏浚底泥进行改良并制备试件,通过无侧限抗压强度(UCS)、抗剪强度(DSS)和加州承载比(CBR)试验研究了改良疏浚底泥的路用基本力学特性,并采用X射线衍射(XRD)和扫描电镜(SEM)辨析了典型土样的物质成分与微观形貌,揭示了不同养护环境、养护时间、菌液掺配比例及胶结物质浓度对微生物固化疏浚底泥力学性能的影响规律。研究发现:混拌MICP法可以用于疏浚底泥的强化处理,30℃且通风良好的养护环境更有利于试件强度的增长;试件强度随着胶结物质浓度的增大呈现先增加后减小的趋势,剪切性能由应变软化逐渐过渡为应变硬化;经过MICP改良后的试件在菌液掺量为100%、胶结水平为1.0 mol·L^(-1),环境温度为30℃且保持良好通风的条件下养护14 d,其UCS由0.16 MPa提升至0.96 MPa,剪切模量E50及黏聚力c、内摩擦角φ也表现出不同程度的提高,常用于表征填料路用性能的CBR提升了5.0%。XRD和SEM分析表明:土颗粒间方解石结晶是试件力学性能提升的原因。采用混拌法基于MICP改良后的疏浚底泥路用性能提升明显,满足路基上路床填料最低要求,可以用于高速公路路基填筑。Basic mechanical properties of microbial-induced calcite precipitation(MICP)-improved dredged sediment soil specimens made using a mixing method were investigated using various test techniques to investigate the feasibility of optimizing the improvement process and improving the road performance of a dredging sediment subgrade filler improved using MICP.Unconfined compressive strength(UCS),direct shear strength,and California bearing ratio(CBR)tests,and X-ray diffraction(XRD)and scanning electron microscopy(SEM)were employed to analyze the material composition and microscopic morphology of typical samples.The effects of different curing environments,curing times,percentages of bacterial solution dosing,and concentrations of cementing substance dosing on the mechanical properties of the MICP-improved dredged sediments were revealed.The results indicate that the mixed MICP method can be used for dredged sediment reinforcement,and the curing condition in a sound ventilation environment at 30℃is more conducive for increasing the sample strength,which first increases and then decreases with an increase in cementing substance concentration.The shear performance gradually transitions from strain softening to strain hardening,and the UCS of the MICP-treated specimens increases from 0.16 to 0.96 MPa.The shear modulus E50,cohesion c,and internal friction angleφalso improve after curing for 14 d under the conditions of a 100%bacterial solution,1.0 mol·L^(-1) cementation level,30℃ambient temperature,and favorable ventilation.The CBR,which typically characterizes the performance of road-filling materials,is improved by 5.0%.XRD and SEM analyses indicate that calcite crystallization formed between soil particles improves the mechanical properties of the specimens.The performance of the dredged sediment is significantly improved using the MICP-based mixing method,which satisfies the minimum requirements for roadbed fillers.Therefore,the improved dredged sediment soil can be used for roadbed filling.

关 键 词：路基工程 微生物诱导碳酸钙沉淀 混拌法 力学性能 疏浚底泥 

分 类 号：U416.1[交通运输工程—道路与铁道工程]