Direct shear tests were conducted to obtain both the shear strength ofcompacted clay liners (CCLs) specimens and the interface shear strength between compacted clay linerand base soil. These experiments were conducted...Direct shear tests were conducted to obtain both the shear strength ofcompacted clay liners (CCLs) specimens and the interface shear strength between compacted clay linerand base soil. These experiments were conducted under the conditions of five different watercontents. The experimental results show that shear strength of both CCLs and CCLs/base interfacedecreases with the increase in the water content of CCLs and base soil. In addition, the considerateconcentration of NaCl in leachate has no deteriorating effect on the shear strength of liners.Triaxial shear tests were also conducted on clay liner specimens to obtain total and effective shearstrength under a fast compression. The shear strength parameters with total stress are φ=18. 5°and c=30 kPa for clay-bentonite, and φ=48. 5° and c=90 kPa for sand-bentonite and those witheffective stress are φ'= 27. 2° and c'=25 kPa for clay-bentonite, and φ'=35° and c'=100 kPa forsand-bentonite, respectively. These results indicate that the compacted clay-bentonite shows normalconsolidation, but that the compacted sand-bentonite exhibits over-consolidation.展开更多
The red clay in Chenzhou, Hunan province is mostly in unsaturated state. Simply applying the mechanical properties that derived from classic saturated soil mechanics often leads to slope failures in this region. In or...The red clay in Chenzhou, Hunan province is mostly in unsaturated state. Simply applying the mechanical properties that derived from classic saturated soil mechanics often leads to slope failures in this region. In order to study the shear strength characteristic of unsaturated red clay in Chenzhou and to explore a shear strength equation that can be easily applied in engineering practice, a series of triaxial tests of saturated and unsaturated red clay samples were performed using the regular triaxial testing apparatus. The testing results show that the peak strength of red clay drops slightly before the moisture content of 30% but decreases sharply after that. The friction angle of red clay under unsaturated state is basically equal to the effective friction angle under saturated state, while the cohesion of unsaturated red clay is far much bigger than that of saturated one, which indicates that the matric suction makes a great contribution to the cohesion. By fitting the testing results with appropriate curves, the relationships between total strength parameters and with moisture content were obtained. The total increases logarithmically before the moisture content of 35% then decreases linearly, while decreases cubically with increasing moisture content.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
文摘Direct shear tests were conducted to obtain both the shear strength ofcompacted clay liners (CCLs) specimens and the interface shear strength between compacted clay linerand base soil. These experiments were conducted under the conditions of five different watercontents. The experimental results show that shear strength of both CCLs and CCLs/base interfacedecreases with the increase in the water content of CCLs and base soil. In addition, the considerateconcentration of NaCl in leachate has no deteriorating effect on the shear strength of liners.Triaxial shear tests were also conducted on clay liner specimens to obtain total and effective shearstrength under a fast compression. The shear strength parameters with total stress are φ=18. 5°and c=30 kPa for clay-bentonite, and φ=48. 5° and c=90 kPa for sand-bentonite and those witheffective stress are φ'= 27. 2° and c'=25 kPa for clay-bentonite, and φ'=35° and c'=100 kPa forsand-bentonite, respectively. These results indicate that the compacted clay-bentonite shows normalconsolidation, but that the compacted sand-bentonite exhibits over-consolidation.
文摘The red clay in Chenzhou, Hunan province is mostly in unsaturated state. Simply applying the mechanical properties that derived from classic saturated soil mechanics often leads to slope failures in this region. In order to study the shear strength characteristic of unsaturated red clay in Chenzhou and to explore a shear strength equation that can be easily applied in engineering practice, a series of triaxial tests of saturated and unsaturated red clay samples were performed using the regular triaxial testing apparatus. The testing results show that the peak strength of red clay drops slightly before the moisture content of 30% but decreases sharply after that. The friction angle of red clay under unsaturated state is basically equal to the effective friction angle under saturated state, while the cohesion of unsaturated red clay is far much bigger than that of saturated one, which indicates that the matric suction makes a great contribution to the cohesion. By fitting the testing results with appropriate curves, the relationships between total strength parameters and with moisture content were obtained. The total increases logarithmically before the moisture content of 35% then decreases linearly, while decreases cubically with increasing moisture content.
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.
