磷石膏稳定土临界动应力及累积变形特性研究  

Study on critical dynamic stress and cumulative deformation characteristics of phosphogypsum stabilized soil

作　　者：陈开圣[1] 张坤 胡兴[1] 王磊[1] CHEN Kaisheng;ZHANG Kun;HU Xing;WANG Lei(College of Civil Engineering,Guizhou University,Guiyang 550025,Guizhou,China)

机构地区：[1]贵州大学土木工程学院,贵州贵阳550025

出　　处：《建筑科学与工程学报》2023年第6期170-180,共11页Journal of Architecture and Civil Engineering

基　　金：贵州省科技计划项目(黔科合基础-ZK[2023]重点016,黔科合支撑[2020]4Y038号)。

摘　　要：针对磷石膏的资源浪费和红黏土的特殊工程特性,以水泥(石灰)为固化剂,采用SDT-20动三轴试验研究了磷石膏稳定土的疲劳特性和改良机理,建立了累积变形模型和临界动应力模型,得到了混合料动强度指标。结果表明:随着动应力幅值与围压提高,累积变形特征显著增大,且素红黏土与磷石膏稳定土变形均经历稳定型、临界型与破坏型三阶段;临界动应力随围压的增大而线性增大,降低动应力水平和提高围压可提升路基抵抗失稳的能力;石灰磷石膏稳定土和水泥磷石膏稳定土动抗剪强度相比素红黏土有大幅提升,且水泥磷石膏稳定土的动抗剪强度增加值比石灰磷石膏稳定土更大;磷石膏稳定土强度提升是由水泥(石灰)和磷石膏共同作用引起的,水泥(石灰)反应生成水化硅酸钙(C—S—H凝胶),磷石膏反应生成钙矾石,两者相互交织形成空间网状结构。In view of the resource waste of phosphogypsum and the special engineering characteristics of red clay,the fatigue characteristics and improvement mechanism of phosphogypsum stabilized soil were studied by SDT-20 dynamic triaxial test with cement(lime)as curing agent.The cumulative deformation model and critical dynamic stress model were established,and the dynamic strength index of the mixture was obtained.The results show that the cumulative deformation characteristics increase significantly with the increase of dynamic stress amplitude and confining pressure,and the deformation of plain red clay and phosphogypsum stabilized soil experiences three stages including stable type,critical type and failure type.The critical dynamic stress increases linearly with the increase of confining pressure.Reducing the level of dynamic stress and increasing confining pressure can improve the ability of subgrade to resist instability.The dynamic shear strengths of lime phosphogypsum stabilized soil and cement phosphogypsum stabilized soil is significantly higher than that of plain red clay,and the increase value of dynamic shear strength of cement phosphogypsum stabilized soi is greater than that of lime phosphogypsum stabilized soil.The strength enhancement of phosphogypsum stabilized soil is the joint action of cement(lime)and phosphogypsum.The cement(lime)reacts to form calcium silicate hydrate(C—S—H gel),the phosphogypsum reacts to form ettringite AFt,and the two are intertwined to form a spatial network structure.

关 键 词：磷石膏稳定土 改良机理 临界动应力 累积变形 动强度 

分 类 号：TU446[建筑科学—岩土工程]