木质素抑制黄土湿陷性试验研究

Collapsibility test on the loess inhibited by lignin

摘要:

黄土湿陷性常引发黄土地区构筑物基础发生沉降甚至破坏,给黄土地区基础设施建设造成了严重的威胁。通过改良黄土可减轻和降低湿陷性的危害,拟采用绿色可降解工业废料木质素对湿陷性黄土进行改良,发现木质素改性黄土可显著减轻黄土湿陷性的危害,并从形变机制和微结构两方面对改良机制进行解释。研究结果表明:2%木质素掺量的黄土试样,其原有的强烈湿陷性已基本消除,改良效果在4%木质素掺量达到峰值;从形变机制看,木质素的加入改变了其结构特征,原本由湿陷性导致的结构失稳在加压期间被释放,致使改良土受湿陷影响降低;从微结构角度看,木质素会使黄土颗粒之间产生新的胶结物,使颗粒之间的联结力增强,从而提升其改良效果。通过室内试验验证木质素在抑制湿陷方面的有效性,2%木质素掺量即可达到改良效果且具有量省效宏的优点,同时符合绿色施工理念并提高工业副产品木质素的利用率,为实际工程解决湿陷问题提供新参考。

Abstract:

Subsidence or even destruction of the foundation of structures in the loess area is often caused by the collapsibility of loess, which poses a serious threat to the infrastructure construction in these areas. Improving loess can help alleviate and reduce the harmful effects of collapsibility. Therefore, this paper investigates the collapsible loess improved by the environmental-friendly degradable industrial waste, that is, lignin. Lignin-modified loess can substantially reduce collapsibility, and the improvement mechanism is explained from the perspective of the deformation mechanism and microstructure. Research results show that 2% lignin content eliminated the collapsibility of the loess sample, and 4% lignin content yielded the best improvement effect. From the perspective of the deformation mechanism, the addition of lignin changes the loess structure. Therefore, the structural instability induced by the collapsibility is released during the pre-pressurization period. From the viewpoint of microstructure, lignin generates new cements between loess particles, which enhances the bonding force between particles. Overall, laboratory experiment results verified the effectiveness of lignin in inhibiting collapsibility. A satisfactory improvement effect is realized by 2% lignin content. The use of lignin conforms to the concept of green construction, improves the utilization rate of industrial byproduct lignin, and provides a new reference for solving the collapsible problem in practical projects.