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膨润土掺量对重塑黄土抗拉强度的影响
王宝仲1, 孟敏强1, 杨秀娟,等1
西北农林科技大学 水利与建筑工程学院
摘要:
【目的】探讨膨润土掺量、含水率和干密度对重塑黄土抗拉强度的影响,为西北地区黄土丘陵沟壑区沟道及坡面治理工程回填黄土拉张裂缝、滑塌等灾害的防治提供参考。【方法】以杨凌黄土为研究对象,制作不同膨润土掺量(0,30,60和90 g/kg)、不同含水率(15%,19%和23%)和不同干密度(1.47,1.57和1.67 g/cm3)共计20组重塑黄土试样,通过拉伸试验仪测定试样的单轴抗拉强度,并以膨润土掺量、含水率和干密度为变量分析试样抗拉强度的变化规律,然后通过压汞试验和扫描电镜试验测定试样内部孔隙大小、孔隙分布规律、土体颗粒结构、接触关系和孔隙内胶体形态,并对单轴抗拉强度的变化规律进行分析。【结果】含水率由15%提高至23%时,试样抗拉强度下降61.54%~71.35%;干密度由1.47提升至1.67 g/cm3时,试样抗拉强度提高115.81%~179.93%;膨润土掺量由0 g/kg提升至90 g/kg时,试样抗拉强度呈先上升后下降的变化趋势,在膨润土掺量为60 g/kg时抗拉强度达到最大,对应增幅为25.74%~57.03%;膨润土掺量为60 g/kg时,颗粒间大孔隙(直径大于5 000 nm)孔径分布密度最低,约为0.01 mL/g。【结论】含水率和干密度是影响重塑黄土抗拉强度的重要因素,膨润土对重塑黄土的抗拉强度有一定改良作用,在掺量为60 g/kg时改良效果最为明显。
关键词:  重塑黄土  膨润土  抗拉强度
DOI:
分类号:
基金项目:陕西省博士后科研资助项目(2018BSHEDZZ23);陕西省自然科学基础研究计划项目(2020JQ-278);中央高校基本科研业务费专项(2452019062)
Effect of bentonite content on tensile strength of remolded loess
WANG Baozhong,MENG Minqiang,YANG Xiujuan,et al
Abstract:
【Objective】This study discussed the influences of bentonite content, moisture content and dry density on the tensile strength of remolded loess to provide reference for the improvement of tensile strength of loess in Northwest China.【Method】A total of 20 groups of remolded loess samples were collected in Yangling with different bentonite contents (0,30,60 and 90 g/kg),moisture contents (15%,19% and 23%) and dry densities (1.47,1.57 and 1.67 g/cm3).The uniaxial tensile strength of samples was measured by the tensile tester,and the variation of tensile strength was analyzed using bentonite content,moisture content and dry density as variables.The pore size,pore distribution,soil particle structure,contact relationship and colloid morphology in the pores of samples were measured by mercury injection test and scanning electron microscope test to analyze the variations of uniaxial tensile strength.【Result】When the moisture content increased from 15% to 23%,the tensile strength of the sample decreased by 61.54%-71.35%. When the dry density increased from 1.47 g/cm3 to 1.67 g/cm3,the tensile strength increased by 115.81%-179.93%.When the content of bentonite increased from 0 g/kg to 90 g/kg,the tensile strength of the sample increased first and then decreased.The tensile strength reached the largest when bentonite content was 60 g/kg and the corresponding increase range was 25.74%-57.03%.The pore size distribution density of macropores (diameter greater than 5 000 nm) between particles was also the lowest of 0.01 mL/g when bentonite content was 60 g/kg.【Conclusion】Moisture content and dry density were the main factors affecting the uniaxial tensile strength of remodeled loess.Bentonite improved the tensile strength of remolded loess and the optimal content was 60 g/kg.
Key words:  remolded loess  bentonite  tensile strength