孟令超, 朴淼, 张鸿秋, 等. 2023. 干湿循环条件下木质素改良膨胀土胀缩特性[J]. 工程地质学报, 31(2): 386-396. doi: 10.13544/j.cnki.jeg.2022-0196.
    引用本文: 孟令超, 朴淼, 张鸿秋, 等. 2023. 干湿循环条件下木质素改良膨胀土胀缩特性[J]. 工程地质学报, 31(2): 386-396. doi: 10.13544/j.cnki.jeg.2022-0196.
    shu
    Meng Lingchao, Piao Miao, Zhang Hongqiu, et al. 2023. Swelling and shrinkage behaviour of expansive soil ameliorated by calcium lignosulphonate dur-ing wetting-drying cycles[J]. Journal of Engineering Geology, 31(2): 386-396. doi: 10.13544/j.cnki.jeg.2022-0196.
    Citation: Meng Lingchao, Piao Miao, Zhang Hongqiu, et al. 2023. Swelling and shrinkage behaviour of expansive soil ameliorated by calcium lignosulphonate dur-ing wetting-drying cycles[J]. Journal of Engineering Geology, 31(2): 386-396. doi: 10.13544/j.cnki.jeg.2022-0196.
    shu

    干湿循环条件下木质素改良膨胀土胀缩特性

    SWELLING AND SHRINKAGE BEHAVIOUR OF EXPANSIVE SOIL AMELIORATED BY CALCIUM LIGNOSULPHONATE DURING WETTING-DRYING CYCLES

      摘要
    • 摘要: 实地调查发现河南省南阳市南阳盆地周边受持续降雨、干旱极端气候影响，出现了房屋破坏、边坡失稳等膨胀土灾害问题，危害人民财产生命安全。以南阳盆地弱膨胀土为研究对象，通过自由膨胀率试验，研究木质素磺酸钙改良弱膨胀土的最佳掺量问题，并在最佳掺量的基础上对试样进行无荷膨胀和收缩试验，进一步研究干湿循环条件下木质素磺酸钙对弱膨胀土胀缩特性的影响，结合试验过程中试样的裂隙发展规律，探究干湿循环条件木质素磺酸钙改良弱膨胀土胀缩特性的原因。试验结果表明对于弱膨胀土，木质素磺酸钙掺量在0.75%、养护天数14 d时改良效果最佳，此时改良土自由膨胀率最低。干湿循环条件下的无荷膨胀和收缩试验数据显示改良前后弱膨胀土绝对膨胀率最高由29%降至3%，绝对收缩率最高由17%降至2%，改良土相对膨胀率与相对收缩率基本不随干湿循环次数发生变化，说明木质素磺酸钙可以有效降低干湿循环过程中弱膨胀土的胀缩形变，保持干湿循环过程中弱膨胀土胀缩特性的稳定，且木质素磺酸钙的改良效果不受干湿循环次数的影响。对比未改良土与改良土裂隙发展规律，木质素磺酸钙在弱膨胀土中主要起到抑制裂隙发育，提高土体胶结能力的作用，使土体形成更致密的结构，改善弱膨胀土胀缩特性。

       

      Abstract: According to a field investigation,expansive soil disasters such as building damage and slope failure happened in the area of Nanyang Basin in Henan Province as a result of extreme climate condition—persistent rains and drought,threatening people's property and lives. This paper aims to study the effect of calcium lignosulphonate for improving the swelling and shrinkage characteristics of weak expansive soil. The soil specimens mixed with calcium lignosulphonate at various percentages(0.5%,0.75%,1%,1.25%) by dry weight,and the free swell test were performed after specimens cured for 0,3,7,11,14,and 28 days to explore the optimum value of calcium lignosulphonate. The laboratory test results indicate that the specimen mixed with 0.75% calcium lignosulphonate and cured for 14 days has the lowest free swelling ratio. Based on the optimum values of calcium lignosulphonate(0.75%),unloaded expansion test and shrinkage test were conducted under cyclic drying and wetting condition. The results show that the addition of calcium lignosulfonate can effectively reduce the absolute expansion rate and the absolute shrinkage rate of weak expansive soil during the wetting-drying cycle. The maximum absolute expansion rate decreases from 29% to 3%,and the maximum absolute shrinkage rate decreases from 17% to 2%. The relative expansion rate and shrinkage rate of ameliorated soils keep steady with the increase of the wetting-drying cycle,which indicates that calcium lignosulfonate can effectively ameliorate the stability of swelling and shrinkage property of weak expansive soil during wetting and drying cycles. The increased drying-wetting cycle has no effect on the improved effectiveness of calcium lignosulphonate. By analyzing the crack development pattern of test specimens,calcium lignosulfonate primarily inhibits crack development,improves soil cementation ability,and causes the soil to form a more compact structure,allowing weak expansive soil to maintain its swelling and shrinkage characteristics stability during the drying-wetting cycle.

       

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