The creep-slip behavior of creeping landslides is closely related to the creep characteristics of slope rock.This study analyzed the creep behavior of ultra-soft mudstone from the Gaomiao landslide in Haidong City,Qin...The creep-slip behavior of creeping landslides is closely related to the creep characteristics of slope rock.This study analyzed the creep behavior of ultra-soft mudstone from the Gaomiao landslide in Haidong City,Qinghai Province,China.Uniaxial creep tests were carried out on ultra-soft mudstone with various moisture contents.The test results indicated that the creep duration of the rock sample with a natural moisture content of 9%is 2400 times longer than that of the sample with a natural moisture content of 13%,while its accumulated strain is 70%of the latter.For the rock sample with a natural moisture content of 9.80%,the creep duration under 0.5 MPa load is 80%of that under 0.25 MPa load,yet the accumulated strain is 1.4 times greater.Additionally,porosity significantly influences the creep behavior of mudstone.Analysis of the cause of the Gaomiao landslide and field monitoring data indicates that the instability of the Gaomiao landslide is related to the moisture content of the landslip mass and external forces.The creep-slip curves of landslides and the creep deformation curves of rocks share a common trend.Precisely identifying the moment when the shift occurs from steady state creep to accelerated creep is critical for comprehending slope instability and rock failure.Moreover,this study delves deeper into the issue of the consistency between landslide creep and rock deformation.展开更多
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 ...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, howeve~ 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 Al2O3 in 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
以1,4-丁二醇(BDO)、聚己二酸丁二醇酯二醇PBA-2000、聚氧化丙烯三醇PPT-3000、聚氧化丙烯二醇PPG-2000、聚氧化丙烯二醇PPG-1000、聚己二酸新戊二醇酯二醇PNA-1000、N,N-二甲基甲酰胺(DMF)、甲苯二异氰酸酯(TDI-80)以及丁酮肟(MEKO)为...以1,4-丁二醇(BDO)、聚己二酸丁二醇酯二醇PBA-2000、聚氧化丙烯三醇PPT-3000、聚氧化丙烯二醇PPG-2000、聚氧化丙烯二醇PPG-1000、聚己二酸新戊二醇酯二醇PNA-1000、N,N-二甲基甲酰胺(DMF)、甲苯二异氰酸酯(TDI-80)以及丁酮肟(MEKO)为原料合成了高固含量封闭型聚氨酯预聚体树脂。以胺类固化剂固化上述封闭型预聚体,得到聚氨酯膜。研究了二乙烯三胺(DETA)、DETA+4,4′-二氨基二环己基甲烷(HMDA)和DETA+HMDA+聚醚胺(D-400)复配固化剂对固化物性能的影响。结果表明,DETA固化所需温度最低,HMDA部分替代DETA后固化时间缩短,这3种固化剂与树脂体系在125℃以下都可实现充分固化,145℃下能实现快速固化。制备超软聚氨酯革树脂的最优工艺条件:100.0 g树脂+0.26 g DETA/0.25 g HMDA/0.6 g D-400+30.0 g DMF+1.0 g BYK-L9565,50℃下初始黏度为3500 mPa·s,得到聚氨酯膜弹性模量为0.49 MPa,伸长率为812%,拉伸强度为8.2 MPa,70℃/RH95%湿热老化试验条件下拉伸强度保留率不低于80%的时间为3周。展开更多
基金The work described in this paper is partially supported by the Second Tibetan Plateau Scientific Expedition and Research Grant(2019QZKK0708)ARC Discovery Project grants(DP210100437,DP230100126),for which the authors are very grateful.
文摘The creep-slip behavior of creeping landslides is closely related to the creep characteristics of slope rock.This study analyzed the creep behavior of ultra-soft mudstone from the Gaomiao landslide in Haidong City,Qinghai Province,China.Uniaxial creep tests were carried out on ultra-soft mudstone with various moisture contents.The test results indicated that the creep duration of the rock sample with a natural moisture content of 9%is 2400 times longer than that of the sample with a natural moisture content of 13%,while its accumulated strain is 70%of the latter.For the rock sample with a natural moisture content of 9.80%,the creep duration under 0.5 MPa load is 80%of that under 0.25 MPa load,yet the accumulated strain is 1.4 times greater.Additionally,porosity significantly influences the creep behavior of mudstone.Analysis of the cause of the Gaomiao landslide and field monitoring data indicates that the instability of the Gaomiao landslide is related to the moisture content of the landslip mass and external forces.The creep-slip curves of landslides and the creep deformation curves of rocks share a common trend.Precisely identifying the moment when the shift occurs from steady state creep to accelerated creep is critical for comprehending slope instability and rock failure.Moreover,this study delves deeper into the issue of the consistency between landslide creep and rock deformation.
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, howeve~ 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 Al2O3 in 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.
文摘以1,4-丁二醇(BDO)、聚己二酸丁二醇酯二醇PBA-2000、聚氧化丙烯三醇PPT-3000、聚氧化丙烯二醇PPG-2000、聚氧化丙烯二醇PPG-1000、聚己二酸新戊二醇酯二醇PNA-1000、N,N-二甲基甲酰胺(DMF)、甲苯二异氰酸酯(TDI-80)以及丁酮肟(MEKO)为原料合成了高固含量封闭型聚氨酯预聚体树脂。以胺类固化剂固化上述封闭型预聚体,得到聚氨酯膜。研究了二乙烯三胺(DETA)、DETA+4,4′-二氨基二环己基甲烷(HMDA)和DETA+HMDA+聚醚胺(D-400)复配固化剂对固化物性能的影响。结果表明,DETA固化所需温度最低,HMDA部分替代DETA后固化时间缩短,这3种固化剂与树脂体系在125℃以下都可实现充分固化,145℃下能实现快速固化。制备超软聚氨酯革树脂的最优工艺条件:100.0 g树脂+0.26 g DETA/0.25 g HMDA/0.6 g D-400+30.0 g DMF+1.0 g BYK-L9565,50℃下初始黏度为3500 mPa·s,得到聚氨酯膜弹性模量为0.49 MPa,伸长率为812%,拉伸强度为8.2 MPa,70℃/RH95%湿热老化试验条件下拉伸强度保留率不低于80%的时间为3周。
