The curves of crack relative length lib and crack growth time t of granite were gained under compressive stresses state according to subcritical crack growth parameters and crack stability growth equation by double-to...The curves of crack relative length lib and crack growth time t of granite were gained under compressive stresses state according to subcritical crack growth parameters and crack stability growth equation by double-torsion constant displacement load relaxa- tion method.The relations between crack relative length and the crack growth time were discussed under different stresses and different crack lengths.The results show that there is a turning point on curve of crack relative length//b and crack growth time of granite.The slope of curve is small when crack relative length is less than the vertical coordinate of the point,and crack grows stably in this case.Cracks grow,encounter and integrate catastro- phically when crack relative length is more than the vertical coordinate of the point,and there is not a gradual stage from crack stability growth to crack instability growth,i.e.rock mass instability is sudden.The curves of crack relative length lib and crack growth time t of granite move to right with decrease of stress σ_1 or crack length a,which implies that limit time increases consequently.The results correspond to practicality.展开更多
The soil samples were collected from a shallow landslide hazard site of the Rangamati Sadar in Bangladesh to determine the shear strength properties of the soil. Multistage triaxial consolidation undrained test has be...The soil samples were collected from a shallow landslide hazard site of the Rangamati Sadar in Bangladesh to determine the shear strength properties of the soil. Multistage triaxial consolidation undrained test has become worldwide more accepted to determine the shear strength parameters. Multistage triaxial undrained tests were performed on five samples taken from five different depths of boreholes. Samples were evaluated under two natural conditions and three remolded situations. Samples were consolidated before shearing at confining pressures from 50 kPa to 1200 kPa. All the test results are discussed in terms of deviator stress versus axial strain, mean effective stress versus deviator curves, stress ratio versus axial strain, and excess p. w. p. versus axial strain curves. The samples consolidated at low effective stress first displayed peak positive values of excess p. w. p., followed by increased strains due to sample bulging failure, and only a few samples formed a shear surface failure. The strength parameters were estimated using the maximum deviator stress as the failure criterion i.e. the overall value of the cohesion is 20 kPa and the friction angle is 34°. Hence, the critical state line has been constructed and the critical state parameters have been calculated. The critical state stress ratio M was calculated to be 0.036. The shear strength of soil is one of the significant mechanical properties that are thoroughly used to assess the landslide and liquefaction potentiality of the soil.展开更多
基金China Postdoctoral Science Foundation(20060400264)CSU Postdoctoral Science Foundationthe National Nature Science Foundation of China(50490274)
文摘The curves of crack relative length lib and crack growth time t of granite were gained under compressive stresses state according to subcritical crack growth parameters and crack stability growth equation by double-torsion constant displacement load relaxa- tion method.The relations between crack relative length and the crack growth time were discussed under different stresses and different crack lengths.The results show that there is a turning point on curve of crack relative length//b and crack growth time of granite.The slope of curve is small when crack relative length is less than the vertical coordinate of the point,and crack grows stably in this case.Cracks grow,encounter and integrate catastro- phically when crack relative length is more than the vertical coordinate of the point,and there is not a gradual stage from crack stability growth to crack instability growth,i.e.rock mass instability is sudden.The curves of crack relative length lib and crack growth time t of granite move to right with decrease of stress σ_1 or crack length a,which implies that limit time increases consequently.The results correspond to practicality.
基金Projects (RDF18-01-23,PGRS1906002,REF-20-01-01) supported by Xi’an Jiaotong-Liverpool University,ChinaProject (KSF-E-19) supported by the Key Program Special Fund。
文摘The soil samples were collected from a shallow landslide hazard site of the Rangamati Sadar in Bangladesh to determine the shear strength properties of the soil. Multistage triaxial consolidation undrained test has become worldwide more accepted to determine the shear strength parameters. Multistage triaxial undrained tests were performed on five samples taken from five different depths of boreholes. Samples were evaluated under two natural conditions and three remolded situations. Samples were consolidated before shearing at confining pressures from 50 kPa to 1200 kPa. All the test results are discussed in terms of deviator stress versus axial strain, mean effective stress versus deviator curves, stress ratio versus axial strain, and excess p. w. p. versus axial strain curves. The samples consolidated at low effective stress first displayed peak positive values of excess p. w. p., followed by increased strains due to sample bulging failure, and only a few samples formed a shear surface failure. The strength parameters were estimated using the maximum deviator stress as the failure criterion i.e. the overall value of the cohesion is 20 kPa and the friction angle is 34°. Hence, the critical state line has been constructed and the critical state parameters have been calculated. The critical state stress ratio M was calculated to be 0.036. The shear strength of soil is one of the significant mechanical properties that are thoroughly used to assess the landslide and liquefaction potentiality of the soil.
