灰岩单轴压缩实验室尺度效应研究

尺度效应广泛存在于缺陷材料中，尺度效应根源于材料的非均匀性。而目前尺度效应研究大都沿用混凝土材料强度负幂率尺度效应研究成果。通过细观结构分析发现，岩石材料和混凝土材料存在较大差别。以灰岩为试验材料，通过单轴压缩试验，获得岩石材料的单轴抗压强度与应力–应变曲线等试验数据，进而分析研究岩石材料的尺度效应及其影响因素，得到与混凝土材料不同的尺度效应规律。研究结果表明：灰岩材料内部的缺陷层次直接决定岩样的强度、变形破坏方式等力学性质；每种非均匀岩石材料都存在一个明显的特征尺度，它与岩石材料内部微缺陷的构造层次(微缺陷自身尺度大小及其相对于岩样尺度的大小)密切相关；岩石材料的尺度效应根源于材料的非均匀性，而并非试件与加载端头之间的端部摩擦效应所造成。

STUDY OF LABORATORY SCALE EFFECT OF LIMESTONE UNDER UNIAXIAL COMPRESSION

Scale effect is widely shown in defective materials while scale effect is mainly originated from material heterogeneity. However，most of the scale effect study followed the research results of negative power law of concrete strength. Through microstructure analysis，much difference exists between rock and concrete materials. Limestone was selected for experimental materials. The experiment data about uniaxial compressive strength and stress-strain curves，etc.，were obtained through uniaxial compressive tests. Based on these data，the scale effect and its influential factors for rock materials are analyzed and studied，which are different from the scaling laws of concrete materials. The research results show that the defect levels in limestone materials influence rock strength，its deformation and failure characteristics heavily. An evident representative scale exists in every heterogeneous rock materials and it is closely related with the defect structural level(defect scale itself and the ratio of defect scale to rock samples scale). Scale effect of rock materials is originated from its heterogeneity，not from the friction effect between the ends of rock sample and loading plate.