粗粒土初始结构效应对颗粒破碎的影响研究

Study on the initial structural effects of particle breakagein coarse-grained soils

为研究粗粒土的初始结构综合特征对其颗粒破碎程度的影响,采用一种改进的直剪试验,获得不同初始结构条件下粗粒土剪切破坏参数,结合图像识别技术,获取直剪过程中粗粒土的结构特征。通过主成分分析法,建立了初始结构综合参数Y 0,以此对不同初始结构粗粒土的结构特征进行定量描述。最终,构建了一种离散元数值模型,该模型真实地反映了颗粒破碎过程。研究结果表明:(1)不同粒径组的颗粒自身破碎程度受其质量分数影响,且整体破碎程度主要由粗颗粒质量分数决定;(2)颗粒破碎程度随法向应力增大呈现线性变化规律,而加权裂离率B d与初始结构综合参数Y 0则呈指数函数关系;(3)在相同法向应力条件下,当颗粒特征强度越大时,不同初始结构间颗粒破碎差异越小,并根据颗粒特征强度σc与加权裂离率B d曲线建立了二者的函数关系式;(4)结合试验结果,最终构建了考虑初始结构效应的粗粒土破碎程度预测模型,并通过相关文献验证了该模型的适用性。

Improved directshear test to determine the parameters of coarse-grained soil under initial structural conditions.The aim to investigate the impact of the comprehensive initial structural characteristics Y 0 of coarse-grained soil on the extent of particle breakage.The structural characteristics of coarse-grained soil direct shear were obtained using image recognition technology initial structures.,discrete element numerical model that accurately represent the particle break.The results:(1)degree of different particle size influenced by their content,the overall degree mainly determined by the presence of coarse particles(2)degree of particle breakage increase linearly with normal stress,while relationship between the weighted separation(B d)and the comprehensive parameter(Y 0).(3)The greater the characteristic strength under the same normal stress,the smaller the difference between different initial structures.A functional relationship established between the characteristic strength of the particles(σc)and the curve of the weighted cleavage(B d).(4)the test resultsa predict the degree of coarse-grained soil the initial verified literature.