粒状材料临界状态的颗粒级配效应

采用理想颗粒材料（DEM理想球体）、人工颗粒材料（玻璃球）和天然颗粒材料（Hostun砂）,通过数值和室内常规三轴排水试验研究了颗粒材料级配对其应力-应变响应和临界状态的影响规律。试验结果表明：在相同加载初始条件下（e₀ = 0.574,p₀' = 400 kPa）,随着不均匀系数C_u（d₆₀/d₁₀）的增大,试样在q-ε₁平面上从剪胀变为剪缩,在ε_v-ε₁平面上表现出由应变软化转变为应变硬化的特性。通过不同围压下的三轴排水试验,在e-p'和q-p'平面上分别对不同级配的颗粒材料集合体绘制了临界状态线,e-p'平面随着C_u的增大临界状态线往下偏移,而在q-p'平面上临界状态线不随C_u的改变而改变。

Grading effect on critical state behavior of granular materials

By adopting the idealized granular materials (DEM sphere), artificial materials (glass bead) and natural materials (Hostun sand), the grading effect on the stress-strain and the critical state behavior of granular materials is investigated through numerical and conventional drained triaxial tests. The results reveal that for the samples with the same initial loading conditions (e₀ = 0.574, p'₀ = 400 kPa), granular materials with a wider particle distribution display more contractive behavior and also strain hardening upon shearing. Furthermore it is found that the critical state line in the e-p' plane shifts downward as grading broadens with an increase of the coefficient of uniformity C_u, whereas the critical state line in the q-p' plane appears to be independent of the coefficient of uniformity C_u.