Abstract:

We explored shear failure resistance mechanisms of terraced fields in mountainous and hilly areas under natural forces. We measured critical shear force of soil using laboratory tests, analyzed the effect of dry-wet alternations on critical shear force of soil, and determined the relationship between critical shear force of soil and soil cohesion following different dry-wet alternation treatments. The results showed (1) during 1-7 dry-wet alternations, the water head difference per unit soil mass was positively correlated with seepage velocity and the soil permeability coefficient increased exponentially with increasing number of dry-wet alternations. (2) With the increasing number of dry-wet alternations, the critical shear force was not significantly affected by 1-3 dry-wet alternations, but increased slightly and stabilized after 4-7 dry-wet alternations. The results show that different dry-wet alternation levels can significantly affect critical shear soil stress and highlights a positive correlation. (3) With increasing critical shear stress, soil cohesion gradually increased, which was significantly correlated. This experiment includes compaction test, dry-wet alternation test and critical shear test. Firstly, the experimental soil was compacted, and then the soil that reached the volume mass set in the experiment was treated with different times (0-7 times) of dry-wet alternation. The critical shear force experiment was carried out for the soil treated with different dry-wet alternation times. The soil head difference per unit height, the permeability coefficient and the critical shear force of the soil were measured, and the relationship between the critical shear force and the soil cohesion was analyzed. The results of this study provide theoretical support for relevant experimental research and engineering practices of terraced fields.

Key words: dry-wet alternation, soil critical shear stress, cohesion, coefficient of soil infiltration