土壤加固剂可改善土体理化特性。选择改性钠羧甲基纤维素(M-CMC)为加固剂,以粉砂土为加固对象,研究M-CMC加固粉砂土水稳性及稳定机理。开展不同加固剂掺量下加固土湿化崩解试验进行崩解状态监测和完全崩解系数(CR)测试,结果显示:随加固剂掺量的增加,试样开始崩解的时间延时、崩解产物中粗粒含量增加、悬浮粒减少,CR快速降低,当掺量达0.9%时,加固土样无崩解。进一步对试样的渗透性、基质吸力、抗剪强度、化学组分及微观结构进行测试,结果显示:随加固剂掺量的增加,加固土样团聚体粒径增大、渗透性减小、基质吸力增大、抗剪强度提高。研究成果表明:M-CMC在土颗粒表面产生“包裹效应”、相邻土颗粒间产生“吸附效应”、相隔土颗粒间产生“连接效应”,使得土颗粒由镶嵌点接触转变为面式接触和链式连接,形成网状胶结结构团聚体,从而提高加固土水稳性。
Abstract
Soil stabilizer can be used to improve the properties of soil. In this study, the water stability and stabilization mechanism of silty sand stabilized by modified carboxymethylcellulose (M-CMC) were investigated via disintegration test of stabilized silty sand dosed with varying content of M-CMC. Monitoring of disintegration and measurement of complete disintegration coefficient (CR) of soil samples suggest that with the augment of M-CMC dosage, the incipient time of disintegration delayed, the content of coarse particles increased, sediment in suspension decreased and the value of CR dropped sharply; no disintegration was observed when the content of M-CMC reached 0.9%. Furthermore, results of infiltration, matric suction, shear strength, chemical composition and microstructure showed that the size of aggregates increased, infiltration coefficient reduced, suction and shear strength both enhanced together with the increasing of M-CMC content, thereby revealing “membrane effect” on the surface of soil particles, “absorption effect” between adjoining particles, and “bonding effect” between aggregates from M-CMC. As a result, the cementation between particles transformed from point contact to line and plane contact, and single particles changed to aggregates with net cementation, which modified the water stability of soil.
关键词
粉砂土 /
改性钠羧甲基纤维素 /
加固剂 /
胶结作用 /
结构团聚体 /
水稳性 /
稳定机理
Key words
silty sand /
modified carboxymethylcellulose /
reinforcement agent /
cementation /
structural aggregate /
water stability /
stabilization mechanism
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基金
国家重点基础研究发展计划(973)项目(2014CB744703);四川省国土资源厅“8·8”九寨沟地震灾区生态化地质灾害防治重大科技支撑研究课题(KJ-2018-20);新疆交通建设集团股份有限公司资助项目(2016010)
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