To assess the effectiveness of vacuum preloading combined electroosmotic strengthening of ultra-soft soil and study the mechanism of the process,a comprehensive experimental investigation was performed.A laboratory te...To assess the effectiveness of vacuum preloading combined electroosmotic strengthening of ultra-soft soil and study the mechanism of the process,a comprehensive experimental investigation was performed.A laboratory test cell was designed and applied to evaluate the vacuum preloading combined electroosmosis.Several factors were taken into consideration,including the directions of the electroosmotic current and water induced by vacuum preloading and the replenishment of groundwater from the surrounding area.The results indicate that electroosmosis together with vacuum preloading improve the soil strength greatly,with an increase of approximately 60%,and reduce the water content of the soil on the basis of consolidation of vacuum preloading,however,further settlement is not obvious with only 1.7 mm.The reinforcement effect of vacuum preloading combined electroosmosis is better than that of electroosmosis after vacuum preloading.Elemental analysis using X-ray fluorescence proves that the soil strengthening during electroosmotic period in this work is mainly caused by electroosmosis-induced electrochemical reactions,the concentrations of Al2O3in the VPCEO region increase by 2.2%,1.5%,and 0.9%at the anode,the midpoint between the electrodes,and the cathode,respectively.展开更多
The characterization of ultra-soft clayey soil exhibits extreme challenges due to low shear strength of such material.Hence,inspecting the non-destructive electrical impedance behavior of untreated and treated ultra-s...The characterization of ultra-soft clayey soil exhibits extreme challenges due to low shear strength of such material.Hence,inspecting the non-destructive electrical impedance behavior of untreated and treated ultra-soft clayey soils gains more attention.Both shear strength and electrical impedance were measured experimentally for both untreated and treated ultra-soft clayey soils.The shear strength of untreated ultra-soft clayey soil reached 0.17 kPa for 10% bentonite content,while the shear strengths increased to 0.27 kPa and 6.7 kPa for 10% bentonite content treated with 2% lime and 10% polymer,respectively.The electrical impedance of the ultra-soft clayey soil has shown a significant decrease from 1.6 kΩ to 0.607 kΩ when the bentonite content increased from 2% to 10% at a frequency of 300 kHz.The10%lime and 10% polymer treatments have decreased the electrical impedances of ultra-soft clayey soil with 10%bentonite from 0.607 kΩ to 0.12 kΩ and 0.176 kΩ,respectively,at a frequency of 300 kHz.A new mathematical model has been accordingly proposed to model the non-destructive electrical impedancefrequency relationship for both untreated and treated ultra-soft clayey soils.The new model has shown a good agreement with experimental data with coefficient of determination（R;）up to 0.99 and root mean square error（RMSE） of 0.007 kΩ.展开更多
海底表层的结构物在使用中可能受到动荷载作用,为保证其的长期稳定性,有必要对海床表层的深海超软土动力学特性展开研究。使用Anton Paar MCR302流变仪,采用应变控制模式,对含水率高于液限的深海超软土进行动态剪切测试,研究动态流变参...海底表层的结构物在使用中可能受到动荷载作用,为保证其的长期稳定性,有必要对海床表层的深海超软土动力学特性展开研究。使用Anton Paar MCR302流变仪,采用应变控制模式,对含水率高于液限的深海超软土进行动态剪切测试,研究动态流变参数、动剪切模量G和阻尼比λ的变化规律。结果表明,随着剪切应变的增大,深海超软土的变形由可恢复的弹性变形主导逐渐过渡为不可恢复的黏性变形主导。通过建立动态流变参数与动剪切模量G和阻尼比λ的关系,探讨了深海超软土的动力特性。根据深海超软土动剪切模量G的变化特征,提出了峰值参考应变的概念,建立了最大动剪模量G_(max)与归一化含水率w/w_(p)(w为含水率,w_(p)为塑性含水率)的关系。结果还显示,相较于常规黏土,深海超软土的G/G_(max-γ)(γ为剪切应变)曲线衰减较快,且受塑性指数影响较小。深海超软土的阻尼比整体偏高,并随剪切应变的增大快速上升。根据试验结果,给出描述深海超软土G/G_(max-γ)、λ-γ曲线的数学模型。展开更多
基金Project(2009B13014) supported by the Fundamental Research Funds for the Central Universities of ChinaProject(IRT1125) supported by the Program for Changjiang Scholars and Innovative Research Team in University,China
文摘To assess the effectiveness of vacuum preloading combined electroosmotic strengthening of ultra-soft soil and study the mechanism of the process,a comprehensive experimental investigation was performed.A laboratory test cell was designed and applied to evaluate the vacuum preloading combined electroosmosis.Several factors were taken into consideration,including the directions of the electroosmotic current and water induced by vacuum preloading and the replenishment of groundwater from the surrounding area.The results indicate that electroosmosis together with vacuum preloading improve the soil strength greatly,with an increase of approximately 60%,and reduce the water content of the soil on the basis of consolidation of vacuum preloading,however,further settlement is not obvious with only 1.7 mm.The reinforcement effect of vacuum preloading combined electroosmosis is better than that of electroosmosis after vacuum preloading.Elemental analysis using X-ray fluorescence proves that the soil strengthening during electroosmotic period in this work is mainly caused by electroosmosis-induced electrochemical reactions,the concentrations of Al2O3in the VPCEO region increase by 2.2%,1.5%,and 0.9%at the anode,the midpoint between the electrodes,and the cathode,respectively.
基金supported by the Center for Innovative Grouting Materials and Technology (CIGMAT) at the University of Houston, Texas, USA
文摘The characterization of ultra-soft clayey soil exhibits extreme challenges due to low shear strength of such material.Hence,inspecting the non-destructive electrical impedance behavior of untreated and treated ultra-soft clayey soils gains more attention.Both shear strength and electrical impedance were measured experimentally for both untreated and treated ultra-soft clayey soils.The shear strength of untreated ultra-soft clayey soil reached 0.17 kPa for 10% bentonite content,while the shear strengths increased to 0.27 kPa and 6.7 kPa for 10% bentonite content treated with 2% lime and 10% polymer,respectively.The electrical impedance of the ultra-soft clayey soil has shown a significant decrease from 1.6 kΩ to 0.607 kΩ when the bentonite content increased from 2% to 10% at a frequency of 300 kHz.The10%lime and 10% polymer treatments have decreased the electrical impedances of ultra-soft clayey soil with 10%bentonite from 0.607 kΩ to 0.12 kΩ and 0.176 kΩ,respectively,at a frequency of 300 kHz.A new mathematical model has been accordingly proposed to model the non-destructive electrical impedancefrequency relationship for both untreated and treated ultra-soft clayey soils.The new model has shown a good agreement with experimental data with coefficient of determination（R;）up to 0.99 and root mean square error（RMSE） of 0.007 kΩ.
文摘海底表层的结构物在使用中可能受到动荷载作用,为保证其的长期稳定性,有必要对海床表层的深海超软土动力学特性展开研究。使用Anton Paar MCR302流变仪,采用应变控制模式,对含水率高于液限的深海超软土进行动态剪切测试,研究动态流变参数、动剪切模量G和阻尼比λ的变化规律。结果表明,随着剪切应变的增大,深海超软土的变形由可恢复的弹性变形主导逐渐过渡为不可恢复的黏性变形主导。通过建立动态流变参数与动剪切模量G和阻尼比λ的关系,探讨了深海超软土的动力特性。根据深海超软土动剪切模量G的变化特征,提出了峰值参考应变的概念,建立了最大动剪模量G_(max)与归一化含水率w/w_(p)(w为含水率,w_(p)为塑性含水率)的关系。结果还显示,相较于常规黏土,深海超软土的G/G_(max-γ)(γ为剪切应变)曲线衰减较快,且受塑性指数影响较小。深海超软土的阻尼比整体偏高,并随剪切应变的增大快速上升。根据试验结果,给出描述深海超软土G/G_(max-γ)、λ-γ曲线的数学模型。
