降低强膨胀土膨胀率提高抗剪强度的复合改良剂筛选

发布时间：2018-05-03 22:00

本文选题：抗剪强度 + 聚乙烯醇　；参考：《农业工程学报》2017年02期

【摘要】：为减小膨胀土对土木工程设施和农业生态环境的严重危害,该文进行复合改良膨胀土方法的室内试验。利用离子交换、高分子成膜作用,使用不同配比的石灰(CaO)、氯化钾(KCl)、聚乙烯醇(polyvinyl alcohol,PVA)、聚丙烯纤维组合对膨胀性土壤进行复合改良。通过54组自由膨胀率试验筛选出自由膨胀率低于40%且性价比高的改良组合(改良剂以质量分数计,下同):0.8%PVA+5%KCl、0.8%PVA+4%CaO。最后根据2种组合设计5组(天然膨胀土、添加0.6%聚丙烯纤维、0.8%PVA+5%KCl、0.8%PVA+5%KCl+0.6%聚丙烯纤维、0.8%PVA+4%CaO)三轴压缩剪切试验,测定抗剪强度并比较改良效果。自由膨胀率试验、三轴压缩剪切试验结果表明复合改良方法效果显著。经过0.8%PVA+5%KCl的混合溶液改性,并添加0.6%聚丙烯纤维改良后的土样自由膨胀率由130%降至27%,三轴抗剪强度提高15%;经过0.8%PVA+4%CaO的混合溶液改性的土样自由膨胀率由130%降至33%,三轴抗剪强度提高110%。研究表明:PVA的成膜效应能强化KCl、CaO对膨胀土水化膨胀的抑制作用;KCl、PVA对聚丙烯纤维提高抗剪强度有抑制作用;聚丙烯纤维能有效减少膨胀土裂隙的萌生,提高抗剪强度。该文提出的强膨胀土复合改良方法的有效性得到了室内试验的验证,可以为今后工程建设中膨胀土的改良、水土流失防治等提供参考。
[Abstract]:In order to reduce the serious harm of expansive soil to civil engineering facilities and agricultural ecological environment, the laboratory test of compound improved expansive soil method was carried out in this paper. By means of ion exchange and polymer film formation, the expanded soil was improved by the combination of different proportion of lime, potassium chloride, polyvinyl alcohol, polyvinyl alcohol and PVA, and the combination of polypropylene fiber was used to improve the expansive soil. Through 54 groups of free expansion tests, the improved combinations with free expansion rate of less than 40% and high performance-to-price ratio were selected. Finally, according to the two combinations, the triaxial compression shear tests were designed for 5 groups (natural expansive soil, adding 0.6% polypropylene fiber and 0.8PVA / KCl 0.8PVA / 0.8PVA 4O) to determine the shear strength and compare the effect of improvement. The results of free expansion test and triaxial compression shear test show that the improved method is effective. Modified by the mixed solution of 0.8%PVA 5%KCl, After adding 0.6% polypropylene fiber, the free expansion ratio of soil sample decreased from 130% to 27%, and the triaxial shear strength increased by 15%, and the free expansion rate of soil sample modified by 0.8%PVA 4O solution decreased from 130% to 33%, and the triaxial shear strength increased by 110%. The results show that the film-forming effect of% PVA can strengthen the inhibition effect of KCl-CaO on hydration and expansion of expansive soil. KCl-PVA can inhibit the increase of shear strength of polypropylene fiber, and polypropylene fiber can effectively reduce the initiation of cracks and increase the shear strength of expansive soil. The effectiveness of the method proposed in this paper has been verified by laboratory tests and can be used as a reference for the improvement of expansive soil and the prevention and control of soil erosion in engineering construction in the future.
【作者单位】：西南大学工程技术学院;
【基金】：国家自然科学基金项目(11572262) 国家大学生创新创业训练计划项目(201510635052) 中央高校基本科研业务费专项资金项目(XDJK2016B006,XDJK2016D016)
【分类号】：TU443

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