冻融循环作用下CMC改良黄土的强度与渗透性研究  

Experimental Study on Strength and Permeability of CMC Improved Loess under Freeze-Thaw Cycles

作　　者：陈孝勇 CHEN Xiao-yong(Qinghai Transportation Planning And Design Institute CO.LTD,Xining 810000,Qinghai Province,China)

机构地区：[1]青海省交通规划设计研究院有限公司,青海西宁810000

出　　处：《中国农村水利水电》2025年第4期117-122,129,共7页China Rural Water and Hydropower

摘　　要：为了探究冻融循环作用下羧甲基纤维素钠(CMC)对渠道垫层重塑黄土的改良效果,在确定最优掺量的基础上,对不同冻融循环次数下的CMC改良黄土和重塑黄土开展渗透试验和三轴剪切试验,对比分析了冻融作用下改良黄土和重塑黄土渗透性和强度特性的变化规律,并根据电镜扫描图像从微观角度讨论了CMC改良黄土的加固机理。结果表明:CMC改良黄土时的最优掺入量为0.5%;冻融循环会导致黄土渗透系数增加,破坏强度减小,黏聚力和内摩擦角衰减,且第1次冻融作用对土样的影响最为显著;CMC掺入能够明显弱化冻融作用对黄土的影响,提高其抗渗性和强度,使得改良黄土的渗透系数显著低于重塑黄土,破坏强度、黏聚力、内摩擦角均大于重塑黄土;CMC掺入黄土能增强土颗粒间的胶结作用,增加摩擦强度,稳定土体结构,显著提高黄土的抗渗性、抗剪强度和抗冻融性能。In order to explore the improvement effect of sodium carboxymethyl cellulose(CMC)on remolded loess of channel cushion under the action of freeze-thaw cycle,based on determining the optimal dosage,permeability tests and triaxial shear tests were carried out on the CMC-modified and remodeled loess under different freeze-thaw cycles,and the changes of permeability and strength characteristics of the improved and remodeled loess under the action of freeze-thaw were compared and analyzed.The strengthening mechanism of CMC-improved loess was discussed from the microscopic point of view according to the scanning images of electron microscope.The results show that the optimal blending amount of CMC is 0.5%.The freeze-thaw cycle can increase the permeability coefficient of loess,decrease the failure strength,decrease the cohesion and internal friction angle,and the first freeze-thaw action has the most significant effect on the soil sample.The addition of CMC can significantly weaken the influence of freeze-thaw on loess,improve its permeability and strength,and make the permeability coefficient of improved loess significantly lower than that of remolded loess,while the failure strength,cohesion and internal friction angle are greater than that of remolded loess.The incorporation of CMC into loess can enhance the cementation between soil particles,increase the friction strength,stabilize the soil structure,and significantly improve the permeability,shear strength and freeze-thaw resistance of loess.

关 键 词：冻融循环 羧甲基纤维素钠 冻融循环 改良黄土 强度 渗透性 

分 类 号：TV41[水利工程—水工结构工程] TU444[建筑科学—岩土工程]