水玻璃-聚丙烯纤维改良膨胀土的强度及裂隙特性  

Sodium silicate solution and polypropylene fiber modified expansive soil strength and crack characteristics

作　　者：肖桂元[1,2] 王浩鹏 邓杰 刘星 杨帅 XIAO Guiyuan;WANG Haopeng;DENG Jie;LIU Xing;YANG Shuai(School of Civil Engineering,Guilin University of Technology,Guilin 541004,China;Guangxi Key Laboratory of Geomechanics and Engineering,Guilin University of Technology,Guilin 541004,China)

机构地区：[1]桂林理工大学土木工程学院,广西桂林541004 [2]桂林理工大学广西岩土力学与工程重点实验室,广西桂林541004

出　　处：《铁道科学与工程学报》2025年第3期1074-1086,共13页Journal of Railway Science and Engineering

基　　金：国家自然科学基金资助项目(52169022)。

摘　　要：为探究在路基工程中应用水玻璃−聚丙烯纤维复合改良膨胀土的效果,将质量比为0、0.5%、1.0%、1.5%、2.5%的水玻璃和0、0.1%、0.2%、0.3%、0.4%、0.5%的聚丙烯纤维掺入膨胀土内。通过无侧限抗压强度试验、干湿循环直剪试验、裂隙试验和扫描电子显微镜(Scanning Eelectron Microscope,SEM)微观试验,研究改良膨胀土的强度及裂隙特性。使用IPP软件对裂隙图像进行处理,探究改良膨胀土的裂隙发育趋势,并结合SEM微观试验,分析水玻璃和聚丙烯纤维在改良膨胀土中的作用机制,探讨其对膨胀土强度和裂隙特性的改进机理。结果表明,水玻璃和聚丙烯纤维均能增强膨胀土的强度,两者复合后土体强度达到峰值且裂隙抑制效果最佳,其最佳配比为水玻璃1%、聚丙烯纤维0.4%。同时,经过1~5次干湿循环后,复合改良土的抗剪强度明显大于素膨胀土,抵抗干湿循环的能力显著。其次,在干湿循环过程中,膨胀土的裂隙发育最快,出现贯穿土体的大裂隙;水玻璃改良土的裂隙发育密集,将土体分割成多个区域;复合改良土裂隙发育程度小且发育缓慢。通过对膨胀土的裂隙面积率、裂隙数目、裂隙平均宽度和裂隙总长度进行定量分析,并结合不同循环次数和单次脱湿过程中的裂隙形态变化,推测出土体的裂隙发育轨迹。最后,通过对SEM图像及裂隙发育图的分析,阐明了裂隙产生的原因,揭示了水玻璃、聚丙烯纤维联合改良膨胀土的内在机理。聚丙烯纤维与水玻璃在土体中生成的硅酸凝胶黏结膜穿插在一起,和土颗粒三者形成纤维硅酸凝胶黏结体系,增加了土颗粒之间的黏结强度,减少了孔隙的连通,从而抑制了裂隙的产生和扩散。研究结果为土体改良技术的选择和评估提供科学依据。To investigate the effectiveness of using sodium silicate-polypropylene fiber composite to improve expansive soil in subgrade engineering,expansive soil samples were mixed with varying mass ratios of sodium silicate(0.0%,0.5%,1%,1.5%,2.5%)and polypropylene fiber(0.0%,0.1%,0.2%,0.3%,0.4%,0.5%).The unconfined compressive strength tests,wet-dry cycle direct shear tests,fissure tests,and SEM(scanning electron microscope)microanalysis were conducted to study the strength and fissure characteristics of the modified expansive soil.IPP software was used to process fissure images,exploring the fissure development trend in the modified soil.The mechanisms of sodium silicate and polypropylene fiber in improving expansive soil were analyzed,focusing on their impact on soil strength and fissure characteristics.The results are as follows.Both sodium silicate and polypropylene fiber enhance the strength of expansive soil.When combined,the soil strength peaked,and fissure inhibition is optimal at a ratio of 1% sodium silicate and 0.4% polypropylene fiber.After 1 to 5 wet-dry cycles,the composite improved soil can exhibite significantly higher shear strength compared to untreated expansive soil,demonstrating enhanced resistance to wet-dry cycles.Furthermore,during the wet-dry cycles,untreated expansive soil can develope extensive fissures.Sodium silicate-modified soils show dense fissure development,dividing the soil into multiple sections.The composite-modified soil can exhibite less and slower fissure development.Quantitative analysis of the fissure area ratio,fissure number,average fissure width,and total fissure length,combined with observations of fissure morphology changes during different cycles and single drying processes,allowed for the prediction of fissure development trajectories.SEM image analysis and fissure development diagrams can elucidate the causes of fissure formation,revealing the internal mechanism of sodium silicate and polypropylene fiber in improving expansive soil.The intertwining of silicon gel adhesive

关 键 词：膨胀土 水玻璃 聚丙烯纤维 干湿循环 裂隙发育 

分 类 号：TU443[建筑科学—岩土工程]