稻壳灰-矿渣固化膨胀土力学与微观特性研究  

Study on mechanical and microscopic characterization of expansive soil solidified by rice husk ash-granulated blast furnace slag

作　　者：李丽华 黄畅[1,2] 李文涛 李孜健 叶治 LI Li-hua;HUANG Chang;LI Wen-tao;LI Zi-jian;YE Zhi(School of Civil Engineering,Architecture and Environment,Hubei University of Technology,Wuhan,Hubei 430068,China;Ecological Road Engineering Research Center,Hubei University of Technology,Wuhan,Hubei 430068,China)

机构地区：[1]湖北工业大学土木建筑与环境学院,湖北武汉430068 [2]湖北工业大学湖北省生态道路工程研究中心,湖北武汉430068

出　　处：《岩土力学》2023年第10期2821-2832,2842,共13页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.52278347,No.U22A20232);湖北省重点研发计划(No.2022BCA059);湖北工业大学杰出人才基金项目(No.XJ2021000501)。

摘　　要：膨胀土具有强胀缩性,吸水极易膨胀软化,失水急剧收缩硬裂,这种胀缩性给工程结构造成很大危害。采用稻壳灰(rice husk ash,RHA)和高炉矿渣(ground granulated blast-furnace slag,GGBS)作为固化剂对膨胀土进行稳定化,通过击实试验、无侧限抗压强度试验、直剪试验、加州承载比(California bearing ratio,CBR)试验、膨胀试验、扫描电镜试验和X射线衍射(X-ray diffraction,XRD)试验,研究了固化后膨胀土的力学强度、膨胀特性变化规律及微观机制。试验结果表明:在不同配比和掺量的固化土中,稻壳灰-矿渣为6:4配比和10%掺量固化土无侧限抗压强度最大;稻壳灰-矿渣(RHA-GGBS,RG)可降低膨胀土轴向变形,提高抗剪强度,随着固化剂掺量增加,固化土黏聚力先增大后减小,内摩擦角逐渐增大;与未处理的膨胀土相比,掺稻壳灰-矿渣固化土CBR值最高可提高至7.9倍,路基土的力学强度得到了显著改善。稻壳灰-矿渣可明显改善膨胀土的膨胀率,减小膨胀力,无荷膨胀率最多可从11.4%下降到0.5%,有荷膨胀率最多可从1.1%趋于0%,膨胀力降幅介于12.1%~62.8%之间。稻壳灰-矿渣可以促进团聚体、无定型水化产物和极少量钙矾石(AFt)的形成,分布在土体表面并填充孔隙,同时可明显减少土中蒙脱石和伊利石亲水矿物成分,增强颗粒之间的胶结作用,从而提高路基土的力学强度,降低固化土膨胀性能。Expansive soil has strong swelling-shrinkage behavior.It swells and softens after absorbing water,and shrinks and cracks after losing water.These swelling-shrinkage behavior will seriously threaten engineering structures.In this study,the expansive soil was stabilized by rice husk ash(RHA)and ground granulated blast-furnace slag(GGBS).Through compaction test,unconfined compressive strength test,direct shear test,California bearing ratio(CBR)test,swelling test,scanning electron microscope test and X-ray diffraction(XRD)test,the mechanical strength,expansion characteristics and microscopic mechanism of solidified expansive soil were studied.Testing results show that the unconfined compressive strength of the stabilized soil with a ratio of RHA to GGBS of 6:4 and a 10%curing agent dosage is the highest among all stabilized soils.The mixture of rice husk ash-ground granulated blast furnace slag(RG)can reduce axial deformation and improve shear strength.With the increase of curing agent content,the cohesion of stabilized soil increases first and then decreases,and the internal friction angle increases gradually.Compared with the untreated expansive soil,the CBR value of the stabilized soil with RG can be increased to 7.9 times,and the mechanical strength of the soil has been significantly improved.RG can significantly reduce the swelling rate of expansive soil and the swelling force.The free swelling rate can be reduced from 11.4%to 0.5%,and the swelling rate with loading can be reduced from 1.1%to 0%.Additionally,the swelling force decreases between 12.1%and 62.8%.RG can promote the formation of flocculation,amorphous hydration products and a very small amount of ettringite(AFt),which are distributed on the surface of the soil and fill the pores so as to improve the strength of the soil and reduce the expansion of the soil.Meanwhile,RG can significantly diminish the hydrophilic minerals such as montmorillonite and illite in the soil and thus enhance the cementation between particles,thereby improving the strength and

关 键 词：稻壳灰 高炉矿渣 膨胀土 无侧限抗压强度 膨胀特性 固化机制 

分 类 号：TU443[建筑科学—岩土工程]