摘要
为了研究人工冻结法对围岩卸荷变形损伤的影响,模拟围岩应力变化路径,并对不同条件下砂岩进行侧向卸荷力学试验和声发射信号监测。研究表明:不同条件下砂岩侧向卸荷总裂纹数和拉伸裂纹数、总累计振铃计数和拉伸裂纹累计振铃计数的时间序列特征基本一致。岩样侧向卸荷变形速率加速增大处(A点)可以作为断裂预警。砂岩冻结后侧向卸荷峰值应力提高了2.3~3倍。冻结岩样初始围压增大,拉伸作用增强,侧向卸荷速率增大,拉伸裂纹减少。冻结岩样初始围压和侧向卸荷速率增大,峰值应力提高,破坏更剧烈。相同条件下岩样侧向卸荷占三轴压缩承载能力的52%~72%。根据侧向卸荷拉伸裂纹数建立的损伤模型,模型结果与试验结果在峰值应力前十分接近,可以表征冻结砂岩侧向卸荷损伤断裂特性。
In order to study the influence of artificial freezing method on the deformation and damage of surrounding rock unloading,the stress change path of surrounding rock is simulated,and the lateral unloading mechanical test and acoustic emission signal monitoring are carried out under different conditions.The results show that the characteristics of total crack number,tensile crack number,cumulative AE count and cumulative AE count of tensile crack are basically the same with time for sandstone under different lateral unloading conditions.The increasing point(point A)of lateral unloading deformation rate of rock sample can be used as fracture warning.The peak stress of lateral unloading of sandstone after freezing is increased by 2.3-3 times.With the increase of initial confining pressure,the tensile action of frozen rock sample is enhanced,the lateral unloading rate is increased,and the tensile crack is reduced.The initial confining pressure and lateral unloading rate of frozen rock sample increase,the peak stress increases,and the failure becomes more severe.Under the same conditions,lateral unloading of rock samples accounts for 52%-72%of the triaxial compression capacity.The damage model is established according to the number of lateral unloading tensile cracks.The model results are very close to the test results before the peak stress,which can characterize the damage fracture characteristics of frozen sandstone under lateral unloading.
作者
刘帅
杨更社
LIU Shuai;YANG Gengshe(College of Architecture and Civil Engineering,Xi'an University of Science and Technology,Xi'an,Shaanxi 710054,China)
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2023年第S02期4237-4247,共11页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金资助项目(42177144)
关键词
岩石力学
冻结砂岩
侧向卸荷
初始围压
卸荷速率
声发射
损伤
rock mechanics
frozen sandstone
lateral unloading
initial confining pressure
unloading rate
acoustic emission
damage
