Currently,the application of the Yellow River silt in subgrade,especially in expressway subgrade,has not been widely promoted.The main reason is that the research on the mechanical characteristics of the Yellow River ...Currently,the application of the Yellow River silt in subgrade,especially in expressway subgrade,has not been widely promoted.The main reason is that the research on the mechanical characteristics of the Yellow River silt used for subgrade filling is extremely limited.In this study,the static shear test of the Yellow River silt under drained condition was carried out using Global Digital Systems(GDS)triaxial apparatus,and the effects of confining pressure,relative density and shear rate on the strength and deformation behavior of the Yellow River silt were investigated.The cohesive force of the Yellow River silt is low,and the friction angle is the main factor determining the shear strength.Friction angle at phase transformation stateφpt,friction angle at peak stateφps,friction angle at critical stateφcs,were obtained via the observation on the evolution law of mobilized friction angle during the whole shearing process.The friction angles corresponding to three different characteristic states have the following magnitude relationship,namelyφps>φcs>φpt.The strength parameters for low-grade subgrade and highgrade subgrade were chosen to be 29.33°and 33.75°.The critical state line(CSL),envelop of phase transformation(EOP),and envelop of dilatancy(EOD)for three different characteristic states were determined.The critical stress ratio M,the phase transformation stress ratio Mptand the dilatancy stress ratio Mdof the Yellow River silt are 1.199,1.235,1.152,respectively.These results provide a basis for the mechanical analysis of the Yellow River silt subgrades and the subsequent establishment of dynamic constitutive model of the Yellow River silt.展开更多
A chain event of the 2016 Kumamoto earthquakes caused considerable geotechnical damage related to liquefaction in many places around Kumamoto plain. Many low-rise houses and traditional Japanese style houses, which we...A chain event of the 2016 Kumamoto earthquakes caused considerable geotechnical damage related to liquefaction in many places around Kumamoto plain. Many low-rise houses and traditional Japanese style houses, which were constructed on <span style="font-family:Verdana;">shallow</span><span style="font-family:Verdana;"> foundation, suffered differential settlement and tilting due to liquefaction. To mitigate the building damages due to the liquefaction</span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">, a new countermeasure method of jet grout grid form with a horizontal slab is introduced in this study.</span></span></span><span><span><span><span style="font-family:""><span style="font-family:Verdana;"> The effectiveness of the proposed technique was evaluated through physical </span><span style="font-family:Verdana;">modelling</span><span style="font-family:Verdana;"> and numerical </span><span style="font-family:Verdana;">modelling</span><span style="font-family:Verdana;">. As </span></span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">a </span></span></span></span><span><span><span><span style="font-family:""><span style="font-family:Verdana;">part of the physical </span><span style="font-family:Verdana;">modelling</span><span style="font-family:Verdana;">, a set of 1 g shaking table tests for </span><span style="font-family:Verdana;">unimproved</span><span style="font-family:Verdana;"> case and improved case were performed, in which the mitigation effects of the grid form with a horizontal reinforcing slab were examined based on the acceleration, excess pore water pressure ratio as well as ground settlement. Numerical simulation was also performed for assessing the effect of </span><span style="font-family:Verdana;">improved</span><span style="font-family:Verdana;"> method on soil-structure interaction and building </span><span style="font-family:Verdana;">settlement</span><span style="font-family:Verdana;"> during the earthquake. </span></span></span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">The physical and numerical results confirmed that the grid form with </span><span style="font-family:Verdana;">horizontal</span><span style="font-family:Verdana;"> slab reinforced method is effective in settlement control and offers favorable contribution </span><span style="font-family:Verdana;">in</span><span style="font-family:Verdana;"> liquefaction mitigation.</span></span></span></span>展开更多
The number of marine landfills in Japan has increased over the past decade due to the lack of suitable land. For marine landfills, protection of the alluvium clay layer and improvement of the drainage performance in w...The number of marine landfills in Japan has increased over the past decade due to the lack of suitable land. For marine landfills, protection of the alluvium clay layer and improvement of the drainage performance in waste inflow are important aspects. In this paper, an economical construction method for these problems is proposed using gravel-tire chips mixture (GTCM) as the horizontal reinforcement and drainage medium beneath the waste. The content and particle size of tire chips mixed with gravel are essential factors that affect the bearing capacity and permeability of the reinforcement layer. Therefore, a series of permeability tests are conducted using newly developed large-scale triaxial compression and permeability test apparatus to investigate the effect of tire chips particle size, the mass proportion of tire chips (MPTC), and triaxial stress on the permeability of GTCM. In addition, the effectiveness of this technique is evaluated by numerical simulations. The experimental results confirm that the shear strength of GTCM is influenced by tire chips content. Furthermore, permeability coefficient of GTCM is on the order of 0.02 cm/s to 0.08 cm/s, which is higher than the tolerable level of permeability of drainage layer in landfills. GTCM sample shows excellent permeability even on higher compression. Moreover, the Non-Darcy flow properties of GTCM (non-linear) are introduced in this study, and an approximate power function relationship between the permeability coefficient and the non-Darcy flow coefficient is developed. The numerical results confirm that GTCM performs better than the sand, a traditional reinforcement material.展开更多
基金National Natural Science Foundation of China(Grant Nos.5217836952109140)+4 种基金Key Projects of High Schools of Henan province of China(20A560021)Natural Science Foundation of Henan Province of China(202300410424)Youth Talent Promotion Project of Henan Province of China(2021HYTP016)Key Specialized Research and Development Breakthrough in Henan Province of China(212102310977)China Postdoctoral Science Foundation(2019M662533)。
文摘Currently,the application of the Yellow River silt in subgrade,especially in expressway subgrade,has not been widely promoted.The main reason is that the research on the mechanical characteristics of the Yellow River silt used for subgrade filling is extremely limited.In this study,the static shear test of the Yellow River silt under drained condition was carried out using Global Digital Systems(GDS)triaxial apparatus,and the effects of confining pressure,relative density and shear rate on the strength and deformation behavior of the Yellow River silt were investigated.The cohesive force of the Yellow River silt is low,and the friction angle is the main factor determining the shear strength.Friction angle at phase transformation stateφpt,friction angle at peak stateφps,friction angle at critical stateφcs,were obtained via the observation on the evolution law of mobilized friction angle during the whole shearing process.The friction angles corresponding to three different characteristic states have the following magnitude relationship,namelyφps>φcs>φpt.The strength parameters for low-grade subgrade and highgrade subgrade were chosen to be 29.33°and 33.75°.The critical state line(CSL),envelop of phase transformation(EOP),and envelop of dilatancy(EOD)for three different characteristic states were determined.The critical stress ratio M,the phase transformation stress ratio Mptand the dilatancy stress ratio Mdof the Yellow River silt are 1.199,1.235,1.152,respectively.These results provide a basis for the mechanical analysis of the Yellow River silt subgrades and the subsequent establishment of dynamic constitutive model of the Yellow River silt.
文摘A chain event of the 2016 Kumamoto earthquakes caused considerable geotechnical damage related to liquefaction in many places around Kumamoto plain. Many low-rise houses and traditional Japanese style houses, which were constructed on <span style="font-family:Verdana;">shallow</span><span style="font-family:Verdana;"> foundation, suffered differential settlement and tilting due to liquefaction. To mitigate the building damages due to the liquefaction</span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">, a new countermeasure method of jet grout grid form with a horizontal slab is introduced in this study.</span></span></span><span><span><span><span style="font-family:""><span style="font-family:Verdana;"> The effectiveness of the proposed technique was evaluated through physical </span><span style="font-family:Verdana;">modelling</span><span style="font-family:Verdana;"> and numerical </span><span style="font-family:Verdana;">modelling</span><span style="font-family:Verdana;">. As </span></span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">a </span></span></span></span><span><span><span><span style="font-family:""><span style="font-family:Verdana;">part of the physical </span><span style="font-family:Verdana;">modelling</span><span style="font-family:Verdana;">, a set of 1 g shaking table tests for </span><span style="font-family:Verdana;">unimproved</span><span style="font-family:Verdana;"> case and improved case were performed, in which the mitigation effects of the grid form with a horizontal reinforcing slab were examined based on the acceleration, excess pore water pressure ratio as well as ground settlement. Numerical simulation was also performed for assessing the effect of </span><span style="font-family:Verdana;">improved</span><span style="font-family:Verdana;"> method on soil-structure interaction and building </span><span style="font-family:Verdana;">settlement</span><span style="font-family:Verdana;"> during the earthquake. </span></span></span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">The physical and numerical results confirmed that the grid form with </span><span style="font-family:Verdana;">horizontal</span><span style="font-family:Verdana;"> slab reinforced method is effective in settlement control and offers favorable contribution </span><span style="font-family:Verdana;">in</span><span style="font-family:Verdana;"> liquefaction mitigation.</span></span></span></span>
文摘The number of marine landfills in Japan has increased over the past decade due to the lack of suitable land. For marine landfills, protection of the alluvium clay layer and improvement of the drainage performance in waste inflow are important aspects. In this paper, an economical construction method for these problems is proposed using gravel-tire chips mixture (GTCM) as the horizontal reinforcement and drainage medium beneath the waste. The content and particle size of tire chips mixed with gravel are essential factors that affect the bearing capacity and permeability of the reinforcement layer. Therefore, a series of permeability tests are conducted using newly developed large-scale triaxial compression and permeability test apparatus to investigate the effect of tire chips particle size, the mass proportion of tire chips (MPTC), and triaxial stress on the permeability of GTCM. In addition, the effectiveness of this technique is evaluated by numerical simulations. The experimental results confirm that the shear strength of GTCM is influenced by tire chips content. Furthermore, permeability coefficient of GTCM is on the order of 0.02 cm/s to 0.08 cm/s, which is higher than the tolerable level of permeability of drainage layer in landfills. GTCM sample shows excellent permeability even on higher compression. Moreover, the Non-Darcy flow properties of GTCM (non-linear) are introduced in this study, and an approximate power function relationship between the permeability coefficient and the non-Darcy flow coefficient is developed. The numerical results confirm that GTCM performs better than the sand, a traditional reinforcement material.