钙质砂颗粒破碎强度及破碎形式研究

Study on Strength and Particle Shape of Calcareous Sand Particle

单颗粒的强度很大程度上决定了岩土体的抗剪强度。通过自制的单颗粒单轴压缩测试仪,对三组平均粒径不同的钙质砂颗粒进行单轴压缩试验,获得垂直载荷与加载位移关系曲线。采用装有高清相机的显微镜拍照以获取单颗粒轮廓图片,用图像处理软件提取颗粒形状参数,研究不同颗粒形状下颗粒破碎形式,得到与颗粒形状参数对应的三种破碎类型,以Weibull分布理论对强度进行统计,得到了平均粒径为1.79mm、3.63mm和8.15mm的颗粒对应的特征应力σ分别为11.23MPa、7.31MPa和4.62MPa,表明粒径越大其破碎强度越低,表现出明显的尺度效应。

It is necessary to study the strength of a single particle since its individual strength might govern the shear strength of the soil or rock mass.The uniaxial compression tests on the individual grain with three different average particle sizes was performed on three different average calcareous sand particle sizes using a house made single particle strength testing device to evaluate the relationship between the vertical load and the correspondent displacement.An optical microscope was used to obtain single particle contour images and an image processing software was used to extract shape parameters.Particle shape parameters were used to evaluate the particle breakage forms under different particle shapes.Three types of breakage models corresponding to the particle shape parameters were derived.The Weibull distribution theory was used to calculate the particle strength.The average particle sizes are 1.79 mm,3.63 mm,and 8.15 mm.The corresponding characteristic stress of the particles are 11.23 MPa,7.31 MPa and 4.62 MPa,respectively.The characteristic strength of the particles decreases with increasing particle size with a strong size effect demonstrated.