摘要
蠕变特性和长期强度是红砂岩地区岩体工程安全评价的关键要素,饱水软化效应对红砂岩蠕变特性和长期强度具有重要影响.采用全自动岩石三轴压缩伺服流变仪,开展天然与饱水红砂岩的三轴压缩试验和三轴压缩蠕变试验.试验结果表明:峰值强度、弹性模量和蠕变破坏应力因饱水软化效应而降低,围压对其降幅有削弱作用,蠕变破坏应力与峰值强度的比值在0.75~0.98之间;饱水软化效应能增强蠕变瞬时变形,减弱蠕变变形及蠕变应变速率;环向应变比轴向应变更早进入稳态蠕变阶段和加速蠕变阶段;稳态蠕变速率与偏压的变化关系符合指数函数关系;长期强度因饱水软化作用而降低,却因围压增加而增大,长期强度与峰值强度的比值在0.62~0.92之间;裂纹损伤应力与长期强度相差较大,裂纹损伤应力视为长期强度有待进一步考究.
Creep mechanical properties as well as long-term strength are considered as the crucial ingredient in the safety evaluation of rock mass engineering in the region of red sandstone.Saturation softening effect plays an important role in creep mechanical properties and long-term strength of red sandstone.Taking red sandstone situating in the site of a dam foundation in Hunan province as the research object,both conventional triaxial compression tests and triaxial creep tests are conducted on natural and saturated red sandstone by the triaxial rock servo-controlling seepage and rheological system V3.The results show peak strength,elastic modulus and creep failure stress decrease due to saturation softening effect,but the degree of their reduction is suppressed by confining pressure.The ratio of creep failure stress to peak strength ranges from 0.75 to 0.98.Instantaneous deformation developed in triaxial creep test is enhanced by saturation softening effect,whereas creep deformation and creep strain rate are weakened.However,the influences of confining pressure on instantaneous deformation,creep deformation and creep strain rate are completely opposite to that of saturation softening effect.The circumstantial strain enters the stable creeping stage and acceleration creeping stage earlier than the axial strain.The relationship of strain rate in stable creeping stage with deviatoric stress can be well described by an exponential function.The long-term strength decreases due to saturation softening effect,but the degree of reduction of long-term strength become small with increasing of confining pressure.The rate of long-term strength to peak strength varies from 0.62 to 0.92.As the crack damage stress is obviously smaller than the long-term strength,it needs further study on the relationship between the crack damage stress and the long-term strength of the red sandstone.
作者
刘桃根
胡凯
李玲
王伟
LIU Taogen;HU Kai;LI Ling;WANG Wei(College of Civil and Construction Engineering,Hunan Institute of Technology,Hengyang 421002,China;Geotechnical Research Institute of Hohai University,Nanjing 210098,China;School of Civil Engineering and Architecture,Jiangxi Polytechnic University,Jiujiang 332007,China)
出处
《三峡大学学报（自然科学版）》
CAS
北大核心
2025年第1期9-15,共7页
Journal of China Three Gorges University：Natural Sciences
基金
江西省青年科学基金资助项目(20202BAB214028)
江西省教育厅科技项目(GJJ190979,GJJ211937)。
关键词
红砂岩
蠕变特性
长期强度
饱水软化效应
裂纹损伤应力
red sandstone
creep properties
long-term strength
saturation softening effect
crack damage stress
