为了探究木质素对新乡地区弱膨胀土的作用效果，通过室内试验、ESEM（环境扫描电子显微镜）试验研究了不同掺量木质素改良新乡地区弱膨胀土的物理性质及力学特性，对不同掺量改良土体微观结构特征及其孔隙形态特征进行定性描述与量化表征，并基于XRD（X射线衍射）试验结果探讨了改良土体中矿物成分的变化，从而揭示木质素与土体间的相互作用机理。试验结果表明：采用木质素改良膨胀土时，3%木质素抑制膨胀土膨胀性效果最好，且此时土体抗压强度最高，超过最优掺量后，土体抗压强度反而降低。土体中孔隙结构复杂，孔隙排列混乱无秩序、定向性较差，木质素胶结物可以填充土体孔隙使其微观结构更加密实。木质素在膨胀土中起胶结作用，并不能与膨胀土反应生成新的矿物成分，与土作用时稳定性较好，属于物理改良。木质素作为一种高效、环保的改良剂，可有效改善膨胀土的基本工程特性，值得深入研究。

In order to explore the effect of lignin on weak expansive soil in Xinxiang area, the physical and mechanical properties of weak expansive soil in Xinxiang area with different lignin contents were examined by laboratory test and ESEM (Environmental Scanning Electron Microscope) test. The microstructure characteristics and pore morphology characteristics of the improved soil with different lignin contents were qualitatively described and quantitatively characterized. Based on the XRD ( X-Ray Diffraction ) testing results, the changes of mineral composition in the improved soil were discussed, so as to reveal the interaction mechanism between lignin and soil. The test results show that when lignin is used to improve expansive soil, 3% lignin has the optimal effect on inhibiting the expansion, and simultaneously the compressive strength reaches the maximum, while the compressive strength of soil decreases after exceeding the optimal dosage. The pore structure in the soil is complex, the pore arrangement is disordered and the orientation is less satisfactory. The lignin cement can fill the soil pores to make its microstructure more dense. Lignin plays a cementing role in expansive soil, and cannot react with expansive soil to form new mineral components. It has satisfactory stability when interacting with soil, which belongs to physical improvement. As an efficient and environmentally friendly modifier, lignin can effectively improve the basic engineering properties of expansive soil, of which further study is promising.

TU443

河南省高等学校重点科研项目（18A580002）；开封市科技发展计划项目（1801004）；甘肃省交通运输厅科研项目（2013-07）