超硫酸盐渍土固化强度及冻融特性试验研究  

Experimental Study on Curing Strength and Freeze-thaw Characteristics of Supersulphate Saline Soil

作　　者：李宏波[1,2,3] 李盛 于广云 丁永发 张轩硕 LI Hongbo;LI Sheng;YU Guangyun;DING Yongfa;ZHANG Xuanshuo(College of Civil and Hydraulic Engineering,Ningxia University,Yinchuan 750021,China;Ningxia Research Center of Technology on Water-saving Irrigation and Water Resources Regulation,Yinchuan 750021,China;Engineering Research Center for Efficient Utilization of Water Resources in Modern Agriculture in Arid Regions,Yinchuan 750021,China;School of Mechanics and Civil Engineering,China University of Mining and Technology,Xuzhou 221116,China)

机构地区：[1]宁夏大学土木与水利工程学院,宁夏回族自治区银川750021 [2]宁夏节水灌溉与水资源调控工程技术研究中心,宁夏回族自治区银川750021 [3]旱区现代农业水资源高效利用教育部工程研究中心,宁夏回族自治区银川750021 [4]中国矿业大学力学与土木工程学院,江苏徐州221116

出　　处：《工程科学与技术》2024年第6期147-160,共14页Advanced Engineering Sciences

基　　金：国家自然科学基金项目(52069025);宁夏自然科学基金重点项目(2023AAC02025);宁夏高等学校一流学科(水利工程学科)项目(NXYLXK2021A03)。

摘　　要：地基强度不足和盐–冻胀破坏是导致盐渍土地区渠道衬砌结构发生破坏的主要原因。为解决盐渍土强度不足的问题,降低盐渍土对环境温度的敏感性,首先,开展联合固化剂对超硫酸盐渍土强度的影响研究,并结合微观测试结果分析,构建联合固化剂掺量与强度之间的关系,对固化效果作出评价;其次,借助压汞试验对微观孔结构进行分析;最后,通过冻融循环试验揭示盐–冻胀力及盐–冻胀量的变化规律。结果表明:固化盐渍土强度增长效果显著,水化产物增强了盐渍土颗粒间的胶结作用。当联合固化剂掺量从0增加至30%时,固化盐渍土的孔隙率逐渐降低,孔径从超大孔向中小微孔演变;模型计算得到的分形维数逐渐增大,其中,Menger海绵模型与Neimark模型表现为多尺度分形,在中孔隙(0.1μm≤孔径<1.0μm)范围分形特征不明显,由热力学模型计算得到的分形维数DT在合理区间2.824~2.849变化,很好地表征了孔隙表面的分形特征。冻融循环10次后,相较未固化盐渍土,固化盐渍土盐–冻胀量削减了117%;盐渍土盐–冻胀力波动范围随冻融次数的增加而逐渐增加,固化盐渍土盐–冻胀力转变为周期性衰减,掺入的联合固化剂有效弱化了盐渍土盐–冻胀力。结合工程实际,建议渠道地基加固中水泥∶粉煤灰∶硅灰∶脱硫石膏质量比为1.00∶1.67∶0.83∶1.00,联合固化剂掺量为30%。Insufficient strength and salt–frost heave failure are the primary causes of channel lining structure failure in saline soil areas.This study conducts strength and microscopic analysis of the supersulphate saline soil treated with a combined curing agent to address the problem of inadequate strength of saline soil and reduce its sensitivity to environmental temperature.The relationship between the curing agent’s dosage and the strength is established to assess the curing effect,and the microscopic pore structure is examined using a mercury injection test.The variation law of frost heave force and quantity is revealed through freeze-thaw cycle testing.The results demonstrated that the strength of solidified saline soil significantly increases,and the hydration products enhance the cementation between particles.As the curing agent’s dosage increases from 0 to 30%,the porosity decreases gradually,the pore size transitions from super-large pore to micro-small pore,and the fractal dimension of the calculation model increases incrementally.The Menger and Neimark model shows multiscale fractal characteristics.In the range of 0.1~1.0μm,the fractal characteristics are not obvious.The fractal dimension(DT)of the thermodynamic model varies within a reasonable range of 2.824 to 2.849,accurately representing the fractal characteristics of the pore surface.After 10 freeze-thaw cycles,the salt–frost heave capacity of solidified saline soil decreased by 117%compared to uncured saline soil.The fluctuation range of salt–frost heave force in solidified saline soil gradually increased with the number of freeze-thaw cycles.The salt–frost heave force of solidified saline soil exhibited periodic attenuation.According to engineering practice,it is recommended that the proportions of cement,fly ash,silica fume,and desulfurized gypsum should be 1.00∶1.67∶0.83∶1.00 and that the dosage of the curing agent should be 30%.

关 键 词：超硫酸盐渍土 固化强度 孔隙分形特征 盐–冻胀量 盐–冻胀力 

分 类 号：TU411.7[建筑科学—岩土工程]