Microscopic parameters of SJCM.

This study utilized synthetic rock mass technology based on the discrete element method implemented in PFC to develop multi-scale limestone-concrete composite (LCC) models in order to examine the size effect of jointed rock-concrete composites (RCC) and assess the impact of joint distribution characteristics on the composite. The variation patterns of the strength properties, deformation characteristics, and failure features with size were analyzed using uniaxial compression tests. Additionally, the impact of the joint dip angle on the size effect of the composite was explored by altering the dip angle range. The results demonstrate that both the uniaxial compressive strength (UCS) and compressive modulus of the LCC exhibit a significant size effect. The calculated difference ratios revealed that the UCS stabilized at dimensions of 600 mm × 1200 mm, whereas the compression modulus decreases by less than 10% and gradually stabilizes. Overall, the deformation characteristics of the composite are less sensitive to size variations than its strength characteristics. During failure, the energy release in the LCC became more dispersed with increasing dimensions. The failure mode transitions from global failure to dispersed localized failure, with crack propagation and stress transfer becoming more dispersed and complex. The range of joint dip angles significantly influences the size effect of the composite. Calculations of the corresponding Δ values indicated that the size effects on UCS and compressive modulus were most pronounced at joint dip angles of 75°–80° and 30°–35°, respectively. Overall, variations in the dip angle range exerted a greater impact on the size effect of UCS than on that of the compressive modulus. These findings provide valuable reference for subsequent research on RCC and related engineering projects.本研究采用基于离散元法（discrete element method）、在PFC中实现的合成岩体技术，构建多尺度石灰岩-混凝土复合材料（limestone-concrete composite, LCC）模型，旨在探究节理岩体-混凝土复合材料（jointed rock-concrete composites, RCC）的尺寸效应，并评估节理分布特征对该复合材料的影响。通过单轴压缩试验，分析了复合材料的强度特性、变形特性与破坏特征随尺寸的变化规律。此外，通过调整节理倾角范围，探究了节理倾角对该复合材料尺寸效应的影响。研究结果表明，LCC的单轴抗压强度（uniaxial compressive strength, UCS）与压缩模量均表现出显著的尺寸效应。计算得到的差值比显示，UCS在尺寸为600mm×1200mm时趋于稳定，而压缩模量的降幅不足10%并逐渐趋于平稳。总体而言，该复合材料的变形特性相较于强度特性，对尺寸变化的敏感性更低。在破坏过程中，LCC内部的能量释放随尺寸增大愈发分散；破坏模式从整体破坏转变为分散的局部破坏，裂纹扩展与应力传递也愈发分散且复杂。节理倾角范围对该复合材料的尺寸效应具有显著影响。对应Δ值的计算结果显示，节理倾角在75°~80°与30°~35°区间时，尺寸效应对UCS与压缩模量的影响最为显著。总体而言，倾角范围的变化对UCS尺寸效应的影响大于其对压缩模量尺寸效应的影响。上述研究结果可为后续RCC相关研究及相关工程实践提供重要参考。