The deep cement mixing(DCM)is used to improve the capacity and reduce the settlement of the soft ground by forming cemented clay columns.The investigation on the mechanical behaviour of the DCM samples is limited to e...The deep cement mixing(DCM)is used to improve the capacity and reduce the settlement of the soft ground by forming cemented clay columns.The investigation on the mechanical behaviour of the DCM samples is limited to either laboratory-prepared samples or in-situ samples under unconfined compression.In this study,a series of drained and undrained triaxial shearing tests was performed on the in-situ cored DCM samples with high cement content to assess their mechanical behaviours.It is found that the drainage condition affects significantly the stiffness,peak and residual strengths of the DCM samples,which is mainly due to the state of excess pore water pressure at different strain levels,i.e.being positive before the peak deviatoric stress and negative after the peak deviatoric stress,in the undrained tests.The slope of the failure envelope changes obviously with the confining pressures,being steeper at lower stress levels and flatter at higher stress levels.The strength parameters,effective cohesion and friction angle obtained from lower stress levels(c′0 andφ′0)are 400 kPa and 58°,respectively,which are deemed to be true for design in most DCM applications where the in-situ stress levels are normally at lower values of 50-200 kPa.Additionally,the computed tomography(CT)scanning system was adopted to visualize the internal structures of DCM samples.It is found that the clay pockets existing inside the DCM samples due to uneven mixing affect markedly their stress-strain behaviour,which is one of the main reasons for the high variability of the DCM samples.展开更多
作者运用 KES 系列织物风格仪和其它测试仪器,对多种苎麻织物的折皱、拉伸、弯曲、剪切和表面摩擦性能进行了测试,并定性地探讨了这些性能的作用机理,以探索苎麻织物的风格特征和改善其机械性能的途径,为合理使用苎麻原料和研制开发苎...作者运用 KES 系列织物风格仪和其它测试仪器,对多种苎麻织物的折皱、拉伸、弯曲、剪切和表面摩擦性能进行了测试,并定性地探讨了这些性能的作用机理,以探索苎麻织物的风格特征和改善其机械性能的途径,为合理使用苎麻原料和研制开发苎麻类产品提供依据。测试结果及分析表明,苎麻织物具有拉伸变形小、抗屈曲性好、折皱回复性盖,手感硬挺、滑爽、活络的风格特征。棉经麻纬交织、麻涤混纺和液氨整理对改善其风格各有独创的优点。展开更多
基金funded by the Environment and Conservation Fund(Grant Nos.2020-170 and 2021-156)the National Natural Science Foundation of China(Grant No.42102327).
文摘The deep cement mixing(DCM)is used to improve the capacity and reduce the settlement of the soft ground by forming cemented clay columns.The investigation on the mechanical behaviour of the DCM samples is limited to either laboratory-prepared samples or in-situ samples under unconfined compression.In this study,a series of drained and undrained triaxial shearing tests was performed on the in-situ cored DCM samples with high cement content to assess their mechanical behaviours.It is found that the drainage condition affects significantly the stiffness,peak and residual strengths of the DCM samples,which is mainly due to the state of excess pore water pressure at different strain levels,i.e.being positive before the peak deviatoric stress and negative after the peak deviatoric stress,in the undrained tests.The slope of the failure envelope changes obviously with the confining pressures,being steeper at lower stress levels and flatter at higher stress levels.The strength parameters,effective cohesion and friction angle obtained from lower stress levels(c′0 andφ′0)are 400 kPa and 58°,respectively,which are deemed to be true for design in most DCM applications where the in-situ stress levels are normally at lower values of 50-200 kPa.Additionally,the computed tomography(CT)scanning system was adopted to visualize the internal structures of DCM samples.It is found that the clay pockets existing inside the DCM samples due to uneven mixing affect markedly their stress-strain behaviour,which is one of the main reasons for the high variability of the DCM samples.
文摘作者运用 KES 系列织物风格仪和其它测试仪器,对多种苎麻织物的折皱、拉伸、弯曲、剪切和表面摩擦性能进行了测试,并定性地探讨了这些性能的作用机理,以探索苎麻织物的风格特征和改善其机械性能的途径,为合理使用苎麻原料和研制开发苎麻类产品提供依据。测试结果及分析表明,苎麻织物具有拉伸变形小、抗屈曲性好、折皱回复性盖,手感硬挺、滑爽、活络的风格特征。棉经麻纬交织、麻涤混纺和液氨整理对改善其风格各有独创的优点。
