含水状态下弱风化泥质粉砂岩冲击破碎的分形规律研究

摘要

水对岩石的物理力学性质影响较大，研究不同含水状态下岩石受冲击荷载后破碎物的分形规律具有较强的现实意义。借助于分离式霍普金森杆（SHPB）实验装置，开展不同含水状态的泥质粉砂岩的冲击试验，然后对破碎物的块度分布进行深入分析，并基于尺寸－频率分析方法，重点对破碎物颗粒粒径分布的分形规律进行探讨。结果表明，随着加载速率的提高，泥质粉砂岩冲击破碎物单块体积普遍减小，残留碎块的数量越多，破碎的程度也越高，此时分形维数越小；含水率越大，小颗粒比例越大，岩样破碎程度越高，饱水状态岩样的分形维数较其他两种状态大，天然含水状态和自然吸水状态岩样冲击破碎的分形维数较为接近；当冲击速度较大时其将成为影响分形维数的主要因素，含水率的影响相对较小。%Water has a great influence on the physical and mechanical properties of the rock.It is very important to investigate the fractal law of rock crushed under impact load at different moisture contents.Using the Split Hopkinson Pressure Bar(SHPB),the impact tests of argillaceous siltstone with different water contents are carried out.The fragmentation distribution of the broken rock is thoroughly presented.According to the method of Size-Frequency,the fractal law of particle size distribution is analyzed.It shows that,the higher the impact velocity,the larger the volume of the singe fragments,the more the amount of the fragments of argillaceous siltstone,the smaller the fractal dimension.The greater the moisture content,the greater the proportion of small particles,the higher the degree of crushing.The fractal dimension of water-saturated rock is bigger than the samples in other two states.The fractal dimensions both in the natural moisture state and natural water absorbing state are almost the same.When the impact velocity is higher,it can become the main factor that affects the fractal dimension,and the influence of the moisture content is smaller.