Research of Shear Strength Characteristics of Compacted Kunming laterite

The compaction characteristics and shear strength characteristics are studied by compaction tests and direct shear tests considering the influence of the moisture contents and hits for Kunming laterite. The results show that the maximum dry density of laterite is increased and the optimum moisture content is reduced with increasing hits,while the dry density is decreased with increasing hits for drier or wetter laterite,which is adverse for compaction of laterite. The features of shear strength of compaction laterite are expressed that,with increasing moisture content,the shear strength and cohesion of drier laterite are increased and the shear strength and cohesion of wetter laterite are decreased; with increasing hits,the shear strength of compaction laterite and cohesion of looser laterite are increased and cohesion of denser laterite is decreased; the shear strength of compaction laterite reaches maximum with an optimum water 3% ~ 5% and 25 hits; and the internal friction angles of compaction laterite are decreased with increasing moisture content and are increased with increasing hits. When the laterite is backfilled,the moisture content and compaction energy of laterite should be carefully controlled in order to ensure its quality.