Analysis of Dispersibility and Mechanical Properties of Lignin Modified Dispersive Soil

Dispersive soil is a kind of special soil with water sensitivity, which is easy to produce ravages such as gully and piping when encountering water in engineering. In order to improve the poor engineering properties of dispersive soil, a kind of lignin was selected to improve the dispersibility and mechanical properties of dispersive soil in western Jilin Province. Pinhole test, fragment test, unconfined compressive strength test and resistivity test were carried out on the improved soil samples with different lignin content. The results showed that lignin could significantly reduce the dispersibility of dispersive soil. With the increasing of curing time, the unconfined compressive strength of the improved soil samples increased gradually. With the increase of lignin content, the unconfined compressive strength of the improved soil first increased and then decreased, and the peak strength appeared when the lignin content was 3%. In the resistivity test, the resistivity of the improved soil decreased gradually with the increase of lignin content. Through microscopic analysis of lignin improved soil samples, it can be concluded that lignin fibers play a stereograin-like bridging role in soil, which promotes the formation of larger aggregates, weakens the dispersion of single soil particles, and thus reduces the dispersion of soil mass and improves the strength of soil mass. This study can provide a basis for the improvement of dispersive soil in seasonal freezing area and has practical engineering significance.