In-situ vane shear test is frequently performed to determine shear strength for slope stability analysis in Tianjin New Harbor.However,the soil shear strength varies with the shear plane orientation.A possible means t...In-situ vane shear test is frequently performed to determine shear strength for slope stability analysis in Tianjin New Harbor.However,the soil shear strength varies with the shear plane orientation.A possible means to reduce the effect of directional dependency of shear strength is to convert the in-situ vane shear strength into undrained shear strength parameters.A method of converting in-situ vane shear strength into undrained shear strength parameters is presented.The shear strength parameters determined for all of the in-situ vane shear strengths are subjected to statistical regression analysis to take into consideration the possible effect of non-homogeneity in the soft clay deposit.Using the regressed shear strength parameters,slope stability analyses are performed for five existing soil slopes.The results of stability analyses indicate that the safety factors obtained from the converted parameters reflect the state of the slopes analyzed much better than those obtained from in-situ vane shear strength and laboratory consolidated-undrained and unconsolidated-undrained strength parameters.It is concluded that the presented methsod of determining undrained shear strength parameters for in-situ vane shear strength is effective.展开更多
The volume change and shear strength behaviour of tailings slurry with the changes in gravimetric moisture content is important to effectively utilise the storage volume and analysis of dam failure potential.Consolida...The volume change and shear strength behaviour of tailings slurry with the changes in gravimetric moisture content is important to effectively utilise the storage volume and analysis of dam failure potential.Consolidation testing of tailings from a slurry-like to soil-like state is a critical task,and conventional consolidation apparatus does not have the capability of doing such testing,as the tailings slurries contain high water content.Settling tests conducted on slurries having a 25%solids concentration showed very low efficiency;final sediment was still slurry-like.An intrinsic point was identified based on pore water pressure dissipation during consolidation tests in a slurry consolidometer that can define two states of the tailings i.e.slurry-like and soil-like.In the slurry-like state,the volume change was greater for Slurry 2 than Slurry 1,while the inverse was observed in the soil-like state.The evolution of peak vane shear strength with the changes in moisture content was almost similar for both samples and obeyed the power function.Regression models have been developed and validated to predict the shear strength of materials at any gravimetric moisture content or void ratio.展开更多
The undrained shear strength(s_u) of fine-grained soils that can be measured in situ and in laboratory is one of the key geotechnical parameters.The unconfined compression test(UCT) is widely used in laboratory to mea...The undrained shear strength(s_u) of fine-grained soils that can be measured in situ and in laboratory is one of the key geotechnical parameters.The unconfined compression test(UCT) is widely used in laboratory to measure this parameter due to its simplicity;however,it is severely affected by sample disturbance.The vane shear test(VST) technique that is less sensitive to sample disturbance involves a correction factor against the soil plasticity,commonly known as the Bjerrum's correction factor,μ.This study aims to reevaluate the Bjerrum's correction factor in consideration of a different approach and a relatively new method of testing.Atterberg limits test,miniature VST,and reverse extrusion test(RET)were conducted on 120 remolded samples.The effect of soil plasticity on undrained shear strength was examined using the liquidity index instead of Bjerrum's correction factor.In comparison with the result obatined using the Bjerrum's correction factor,the lindrained shear strength was better represented when s_u values were correlated with the liquidity index.The results were validated by the RET,which was proven to take into account soil plasticity with a reliable degree of accuracy.This study also shows that the RET has strong promise as a new tool for testing undrained shear strength of fine-grained soils.展开更多
文摘In-situ vane shear test is frequently performed to determine shear strength for slope stability analysis in Tianjin New Harbor.However,the soil shear strength varies with the shear plane orientation.A possible means to reduce the effect of directional dependency of shear strength is to convert the in-situ vane shear strength into undrained shear strength parameters.A method of converting in-situ vane shear strength into undrained shear strength parameters is presented.The shear strength parameters determined for all of the in-situ vane shear strengths are subjected to statistical regression analysis to take into consideration the possible effect of non-homogeneity in the soft clay deposit.Using the regressed shear strength parameters,slope stability analyses are performed for five existing soil slopes.The results of stability analyses indicate that the safety factors obtained from the converted parameters reflect the state of the slopes analyzed much better than those obtained from in-situ vane shear strength and laboratory consolidated-undrained and unconsolidated-undrained strength parameters.It is concluded that the presented methsod of determining undrained shear strength parameters for in-situ vane shear strength is effective.
文摘The volume change and shear strength behaviour of tailings slurry with the changes in gravimetric moisture content is important to effectively utilise the storage volume and analysis of dam failure potential.Consolidation testing of tailings from a slurry-like to soil-like state is a critical task,and conventional consolidation apparatus does not have the capability of doing such testing,as the tailings slurries contain high water content.Settling tests conducted on slurries having a 25%solids concentration showed very low efficiency;final sediment was still slurry-like.An intrinsic point was identified based on pore water pressure dissipation during consolidation tests in a slurry consolidometer that can define two states of the tailings i.e.slurry-like and soil-like.In the slurry-like state,the volume change was greater for Slurry 2 than Slurry 1,while the inverse was observed in the soil-like state.The evolution of peak vane shear strength with the changes in moisture content was almost similar for both samples and obeyed the power function.Regression models have been developed and validated to predict the shear strength of materials at any gravimetric moisture content or void ratio.
文摘The undrained shear strength(s_u) of fine-grained soils that can be measured in situ and in laboratory is one of the key geotechnical parameters.The unconfined compression test(UCT) is widely used in laboratory to measure this parameter due to its simplicity;however,it is severely affected by sample disturbance.The vane shear test(VST) technique that is less sensitive to sample disturbance involves a correction factor against the soil plasticity,commonly known as the Bjerrum's correction factor,μ.This study aims to reevaluate the Bjerrum's correction factor in consideration of a different approach and a relatively new method of testing.Atterberg limits test,miniature VST,and reverse extrusion test(RET)were conducted on 120 remolded samples.The effect of soil plasticity on undrained shear strength was examined using the liquidity index instead of Bjerrum's correction factor.In comparison with the result obatined using the Bjerrum's correction factor,the lindrained shear strength was better represented when s_u values were correlated with the liquidity index.The results were validated by the RET,which was proven to take into account soil plasticity with a reliable degree of accuracy.This study also shows that the RET has strong promise as a new tool for testing undrained shear strength of fine-grained soils.
