干湿循环中磷石膏基防渗材料的防渗和剪切特性  

Impermeability and shear strength of phosphogypsum-based impermeable materials under drying-wetting cycles

作　　者：宋牧原 王宜将 杨微 郎丰飞[5] 陈伟 刘雪莹[1,2,3] SONG Muyuan;WANG Yijiang;YANG Wei;LANG Fengfei;CHEN Wei;LIU Xueying(Key Laboratory of Building Safety and Energy Efficiency of Ministry of Education,Hunan University,Changsha 410082,China;National Center for International Research Collaboration in Building Safety and Environment,Hunan University,Changsha 410082,China;College of Civil Engineering,Hunan University,Changsha 410082,China;Chonfar Engineering and Technology Co.Ltd,Changsha 410000,China;Hubei Dayukou Chemical Co.Ltd,Zhongxiang 431911,China)

机构地区：[1]湖南大学建筑安全与节能教育部重点实验室,湖南长沙410082 [2]湖南大学建筑安全与环境国际联合研究中心,湖南长沙410082 [3]湖南大学土木工程学院,湖南长沙410082 [4]中蓝长化工程科技有限公司,湖南长沙410000 [5]湖北大峪口化工有限责任公司,湖北钟祥431911

出　　处：《浙江大学学报（工学版）》2024年第9期1902-1911,共10页Journal of Zhejiang University：Engineering Science

基　　金：国家自然科学基金资助项目(52078207);国家自然科学基金青年科学基金资助项目(41807261);湖南省科技计划资助项目(2022RC1174).

摘　　要：研制新型聚丙烯酸钠改性膨润土-砂-磷石膏(PMB-S-PG)防渗材料,用于磷石膏渣场或路基防渗层,为多途径消纳磷石膏提出新思路.对比PMB-S-PG、钠基膨润土-砂-磷石膏(RB-S-PG)与聚丙烯酸钠改性膨润土-砂(PMB-S)在干湿循环下的防渗及剪切特性,并结合扫描电子显微镜(SEM)及压汞(MIP)试验探明干湿(DW)循环下试样防渗和强度弱化的微观机理.结果表明:试样RB-S-PG、PMB-S-PG及PMB-S的渗透系数在9次循环后分别上升了146.5倍、6.14倍及1.59倍,说明PMB有效提升了试样的抗干湿循环能力.试样抗剪强度的大小关系为PMB-S-PG>RB-S-PG>PMB-S,表明PG和PMB有助于提升试样的抗剪强度.试样的抗剪强度均随干湿循环次数的增加呈先降低后稳定的变化趋势.通过MIP试验发现试样PMB-S-PG中孔隙随循环次数的增加由单峰演变为三峰结构,3个峰相应粒径的孔隙体积和数量不断增加,颗粒间胶结弱化,但试样中孔隙体积增量逐渐减小,可见在干湿循环作用下,试样的防渗及强度特性先弱化而后趋于稳定.New sodium polyacrylate modified bentonite-sand-phosphogypsum(PMB-S-PG)impermeable material was developed for PG slag field or roadbed impermeable layers,which can provide a new idea for multiple ways to dispose PG.The properties of impermeability and shear strength for PMB-S-PG,raw bentonite-sandphospho gypsum(RB-S-PG)and sodium polyacrylate modified bentonite-sand(PMB-S)under the drying-wetting(DW)cycles were compared,and the micro-mechanisms of the impermeability and the strength weakening for the specimens under the action of DW cycles were investigated by scanning electron microscope(SEM)and mercury intrusion porosimetry(MIP)tests.Results showed that the coefficients of permeability for the RB-S-PG,PMB-S-PG and PMB-S specimens increased by 146.50,6.14 and 1.59 times after 9 DW cycles,respectively,indicating that the PMB can effectively improve the resistance of the specimens for DW cycles.The relationship of the shear strength for three specimens was as follows:PMB-S-PG>RB-S-PG>PMB-S,indicating that the PG and the PMB both helped to improve the shear strength of the specimens.The shear strength of the specimens showed a change trend of decreasing first and then stabilizing with the increasing number of DW cycles.By the MIP tests,it was found that the pore structure of the PMB-S-PG specimen changed from single-peak to three-peaks structure with the increasing number of DW cycles.The pore volume and number corresponding to the particle size of the three peaks increased continuously,which led to the weakening of interparticle cementation,but the increment of the pore volume of the specimen decreased gradually.In the effect of DW cycles,the properties of impermeability and strength for the specimen first weakened and then tended to be stable.

关 键 词：磷石膏(PG) 干湿(DW)循环 渗透系数 抗剪强度 孔隙结构 

分 类 号：TU411[建筑科学—岩土工程]