藏东南砂土改良加固力学性能及干湿循环试验研究  

Mechanical Properties and Wet and Dry Cycling Tests of Reinforced Sandy Soil Improvement in Southeast Xizang

作　　者：桑鼎 牛欢 李超 赵哲苇 王培清[1,2] 仉文岗 SANG Ding;NIU Huan;LI Chao;ZHAO Zhe-wei;WANG Pei-qing;ZHANG Wen-gang(Research Center of Civil,Hydraulic and Power Engineering of Xizang,Xizang Agriculture and Animal Husbandry University,Linzhi 860000,China;College of Water Conservancy and Civil Engineering,Xizang Agriculture and Animal Husbandry University,Linzhi 860000,China;School of Civil Engineering,Chongqing University,Chongqing 400045,China)

机构地区：[1]西藏农牧学院,西藏土木水利电力工程技术研究中心,林芝860000 [2]西藏农牧学院水利土木工程学院,林芝860000 [3]重庆大学土木工程学院,重庆400045

出　　处：《科学技术与工程》2025年第3期1188-1196,共9页Science Technology and Engineering

基　　金：国家自然科学基金区域创新发展联合基金重点项目(U22A20594);西藏自治区科技厅自然科学基金重点项目(XZ202201ZR0068G);西藏农牧学院研究生教育创新计划项目(YJS2024-45)。

摘　　要：为研究高分子聚合物聚乙烯醇(polyvinyl alcohol,PVA)和聚丙烯纤维对藏东南松散堆积砂土复合改良效果,在室内开展无侧限抗压强度试验及直接剪切试验,研究改良砂土效果,并确定最佳改良材料掺配比例;分析干湿循环后改良砂土在水分侵蚀下强度变化,并对其加固机理进行分析。研究结果表明:PVA与聚丙烯纤维掺量对无侧限抗压强度均有明显影响,当掺比为12%PVA+0.25%聚丙烯纤维时改良效果最优,其无侧限抗压强度可达1716 kPa,与砂土无侧限抗压强度25.46 kPa相比,强度增长达67倍。不同纤维含量的改良试样其抗剪强度随PVA掺量的增加而增加。在经历10次干湿循环过程后,12%PVA+0.25%聚丙烯纤维试样其无侧限抗压强度约为748.66 kPa,仍有7 d强度的91.8%。同龄养护期28 d的1.47倍。聚乙烯醇溶液形成高分子膜黏附包裹砂土,聚丙烯纤维缠绕填充砂土,两者相结合提高了砂土的稳定性,有效改善了土颗粒之间的黏结强度,提高了土体的抗压强度。To investigate the impact of polymer polyvinyl alcohol(PVA)and polypropylene fiber on the composite enhancement of loosely piled sandy soil in Southeast Xizang,unconfined compressive strength tests and direct shear tests were conducted.The the effects of the improved sandy soil was understood and the optimal mixing ratio of the improved materials was determined.Additionally,the change in the strength of the improved sandy soil under water erosion after dry and wet cycles was analyzed,and the reinforcement mechanism was investigated.The results demonstrate that the dosage of PVA and polypropylene fibers has a significant effect on the un-confined compressive strength.The best improvement effect is achieved with a dosage ratio of 12%PVA+0.25%polypropylene fi-bers,resulting in an unconfined compressive strength of 1716 kPa.This is 67 times higher than that of sandy soil with an unconfined compressive strength of 25.46 kPa.The shear strength of the improved specimens with different fiber contents increased with the in-crease of PVA doping.After 10 dry and wet cycling processes,the 12%PVA+0.25%polypropylene fiber specimen exhibited an unconfined compressive strength of about 748.66 kPa,which was still 91.8%of the strength at 7 days and 1.47 times that of the same age maintenance period of 28 days.Polyvinyl alcohol solution formed a polymer film that adhered to and wrapped the sandy soil,while polypropylene fiber wound and filled the sandy soil.The combination of these two materials improved the stability of the sandy soil,ef-fectively enhancing the bonding strength between soil particles and increasing the compressive strength of the soil body.

关 键 词：砂土 无侧限抗压强度 直剪试验 干湿循环 机理分析 

分 类 号：TU411[建筑科学—岩土工程]