初始相对密实度对粗颗粒土K0影响试验研究

The at-rest earth pressure coefficient is an important mechanical parameter of soil, so the study of the at-rest earth pressure coefficient of coarse grained soil has important theoretical value and practical significance. The relevant research about the influence of initial relative density on at-rest earth pressure coefficient of coarse grained soil is almost blank. To study the at-rest earth pressure coefficient behavior of coarse grained soil with different initial relative density, by changing initial relative density of a sandy gravel and a rockfill with the same gradation, a number of tests to obtain the at-rest earth pressure coefficient behavior of these test specimens were performed using a new-developed large-size apparatus. The test data showed that the at-rest earth pressure coefficient decreases with increasing effective vertical stress, and the tendency of decreasing at-rest earth pressure coefficient trends to weaken with increasing effective vertical stress. There exists a linear negative correlation between the values of at-rest earth pressure coefficient and initial relative density for coarse grained soil. The at-rest earth pressure coefficient is influenced by soil type. During the loading the at-rest earth pressure coefficient of sandy gravel is 4.0%~7.5% greater than that of rockfill, and during the unloading the at-rest earth pressure coefficient of sandy gravel is 0~12.4% greater than that of rockfill. The analysis of the test data of rockfill showed that the relation between at-rest earth pressure coefficient and effective vertical stress, developed by the authors, is appropriate for coarse grained soil with initial relative density that is not zero. Based on the relation, an empirical formula, which can describe well the relationship of effective vertical stress and initial relative density to at-rest earth pressure coefficient for coarse grained soil, was obtained. Furthermore，this empirical formula was verified by test data of sandy gravel.