不同加载速率下软硬互层类岩石力学及声发射特性

Mechanical Properties and Acoustic Emission Characteristics of Soft-Hard Interbedded Rocks Under Different Loading Rates

基于三峡库区砂泥岩互层岩体实测数据,制作软硬互层类岩石试样,在单轴压缩条件下,探究不同静态加载速率对不同厚度比、不同岩层组合方式岩样的力学及声发射特性的影响.研究结果表明:加载速率和硬软岩体积比是影响峰值强度的主要因素,而加载速率和硬软岩岩层厚度比是影响最终破坏特征的主要因素.一方面,随着加载速率的增大,软硬互层类岩石峰值强度先减小后增大;硬岩占比与岩样抗压强度呈正相关;另一方面,低加载速率下岩样最终破坏模式为材料充分破坏,较高加载速率下岩样最终形成1~2条贯穿软硬岩层的主破裂面;软岩体积占比越少,软岩受到的破坏程度越剧烈;此外,可以把AF值突增、b值骤降作为软硬互层岩体大面积破坏的预警信号.

Based on the measured data of sandstone mudstone interbedded rock mass in the Three Gorges Reservoir area,the soft-hard interbedded rock samples were made.Under uniaxial compression,the effects of different static loading rates on the mechanical and acoustic emission characteristics of rock samples with different thickness ratios and different rock formation combinations were explored.The results show that the loading rate and the volume ratio of hard and soft rock are the main factors affecting the peak strength,while the loading rate and the thickness ratio of hard and soft rock are the main factors affecting the final failure characteristics.On the one hand,with the increase of loading rate,the peak strength of the soft-hard interbedded rocks decreases first and then increases;The proportion of hard rock is positively correlated with the compressive strength of rock samples.On the other hand,the ultimate failure mode of rock samples at low loading rate is complete failure of materials,and at high loading rate,1~2 main fracture surfaces penetrating soft and hard rock layers are finally formed.The less the volume proportion of soft rock,the more severe the damage to soft rock.In addition,the sudden increase of AF value and the sudden decrease of b value can be taken as early warning signals of large-scale damage of the soft-hard interbedded rock mass.