Influencing factors for shear strength of Malan and Lishi compacted loess in Lanzhou

The shear strength is the most important mechanical index of loess, which strongly depends on the degree of compaction and moisture content. To investigate the performance of Malan and Lishi loess, direct shear tests are conducted on the samples taken from undisturbed loess site in Qingbaishi, Lanzhou. The shear strength indexes including the cohesion and internal friction angle under different degrees of compaction and moisture contents are obtained. The effects of compaction and moisture content of Lishi and Malan compacted loess are studied. The results show that the cohesion increase with the increase of compaction, and that of Lishi loess has greater increase than that of Malan loess. The cohesion increases slightly with the increase of moisture content when it is less than optimum water, while the cohesion decreases sharply with the increase of moisture content when it is greater than the optimum moisture content. The internal friction angle increases with the increase of compaction and slightly decreases with the increase of water content of compacted Lishi and Malan loess.