多孔材料的孔结构对其力学性能及破裂机制的影响

针对多孔材料的孔结构对其宏观力学性能及其破裂机制与耐久性的影响，对两种不同孔结构的多孔材料进行了单轴压缩和冻融循环试验，建立了能反映材料内部孔隙结构的三维非均匀数值模型，对两种多孔材料在单轴压缩下的破裂机制进行了分析.实验结果表明:孔结构对于金尾矿多孔材料的力学性能有显著影响.较大的孔隙率除会显著降低材料的抗压强度外，吸能性能会显著增加;在±25℃范围内冻融循环10次条件下的试验结果表明，当金尾矿多孔材料的孔隙率较小且为闭孔结构时，孔洞因冻融造成的孔壁颗粒脱落填塞而造成材料的抗冻性能有所提高;孔隙率较小时，金尾矿多孔材料在单轴压缩下的裂纹扩展主要从试件两端向试件中部扩展贯通为一条连续主拉裂纹，次生裂纹较少;而孔隙率较大时，压缩过程会出现大量微裂纹，最终主裂纹附近会伴随大量次生裂纹.

Effect of Pore Structure on Mechanical Properties and Fracture Mechanism of Porous Materials

In order to study the effect of pore structure on the mechanical properties， fracture mechanism and durability of altered rock porous materials， the uniaxial compression and freeze-thaw cycle experiments were carried out on two types of porous materials with different pore structures. Meanwhile， numerical simulation was conducted to analyze the failure process and failure mechanism of the two porous materials under uniaxial compression. The results show that the pore structure has a significant effect on the mechanical properties of porous materials. The larger the porosity， the lower the compressive strength and the higher the energy absorption. The 10-cycle freeze-thaw experiments in the range of ±25℃ show that when the porosity is small and closed， the frost resistance of the material increases due to the particle falling and filling of the pore wall by the freeze-thaw effect， and when the porosity is small， the crack propagation under uniaxial compression mainly extends from both ends of the specimen to the middle of the specimen， forming a continuous main tensile crack with few secondary cracks; when the porosity is large， a large number of microcracks will appear under compression with many secondary cracks.