Experimental Study on Influence Factors and Empirical Formula of K0 for Coarse Grained Soil

The earth pressure coefficient at rest K 0 is a key mechanical parameter of soil, so studying K 0 of coarse grained soil has important theoretical value and practical significance in geotechnical engineering works. To investigate the influence factors of K 0 for coarse grained soil, a series of K 0 compression tests for a sandy gravel and a rockfill were conducted by utilizing a newly-developed large-scale K 0 device. The test data show that there is a negative linear correlation between K 0 and initial relative density D r 0 . The data also show that the increasing vertical effective stress σ′ v , will decrease the K 0 value, and the effect of low σ′ v , on the K 0 is more obvious. Large-scale consolidated drained (CD) triaxial tests for soils used for K 0 compression test were carried out, and according to the data of CD triaxial tests and K 0 compression tests the correlation between K 0 and effective internal friction angle ϕ ′ is established. Based on the result, an empirical equation is presented. This equation can be used to predict the K 0 value of the coarse grained soil under a random consolidation condition and stress condition according to the value of ϕ ′. Furthermore, this empirical formula is verified by K 0 compression tested data.