A new triaxial apparatus was designed and manufactured. It is able to applysurcharge and combined vacuum-surcharge pressures on soil samples, and allows for monitoring ofexcess pore-water pressure, axial strain or set...A new triaxial apparatus was designed and manufactured. It is able to applysurcharge and combined vacuum-surcharge pressures on soil samples, and allows for monitoring ofexcess pore-water pressure, axial strain or settlement, and volumetric strain during the process ofconsolidation. Tests were performed using the apparatus on undisturbed soft clayey soil samples,which were collected from Wenzhou, Zhejiang Province, China, at average natural water content 72. 5%. The consolidation behavior of theclay has no rigorous difference, whether it is consolidatedunder the vacuum, surcharge, or combined vacuum-surcharge preloading. The study shows that somephysical properties of the soft clayey soils are changed and mechanical properties are improved tosupport excessive loads transferred to the soil foundation due to construction.展开更多
客车制动缸膜板的稳定工作对制动系统的安全性和可靠性具有决定性意义。制动缸膜板直径较大,密封圈处螺栓数量较多且工况复杂,分析表明其安装方式及温度对密封性能影响显著。文中采用有限元分析方法研究顺次加载、ASME PCC-1加载、JIS B...客车制动缸膜板的稳定工作对制动系统的安全性和可靠性具有决定性意义。制动缸膜板直径较大,密封圈处螺栓数量较多且工况复杂,分析表明其安装方式及温度对密封性能影响显著。文中采用有限元分析方法研究顺次加载、ASME PCC-1加载、JIS B 2251加载方式对螺栓预紧力的影响。同时分析了温度变化对螺栓预紧力以及膜板密封面应力分布的影响,并且对制动缸进行了不同温度下的密封性能试验。结果表明,3种加载方式最后都能得到较为均匀的载荷,其中JIS B 2251加载方式最接近目标载荷,加载过程最简易;随着温度的升高,螺栓预紧力上升,密封面上的接触应力增大;低温状态下制动缸内压力下降最快,高温次之,常温最慢。展开更多
This paper presents model tests(macro aspect)and microstructure tests(micro aspect)for investigating the consolidation behavior of Tianjin dredged clay using the prefabricated vertical drain air-booster vacuum preload...This paper presents model tests(macro aspect)and microstructure tests(micro aspect)for investigating the consolidation behavior of Tianjin dredged clay using the prefabricated vertical drain air-booster vacuum preloading(PAVP)and tube air-booster vacuum preloading(TAVP)methods.The mechanism of air-booster vacuum preloading(AVP)using a spring-like system is explained.The main difference between these two methods is the air-boosting equipment.A new anticlogging air-booster prefabricated vertical drain(PVD)is used in the PAVP technique and a self-designed air-booster tube is used in the TAVP technique.In the model tests,a comparison of the variables that are monitored during reinforcement(vacuum pressure,surface settlement,water discharge,and pore-water pressure)and after reinforcement(water content,dry density,and vane shear strength)is conducted.The results indicate that the consolidation behavior of Tianjin dredged clay using the PAVP method is better than that using the TAVP method.PAVP more efficiently mitigates the issue of water-draining PVD clogging and significantly accelerates drainage consolidation.In addition,in the microstructure tests,a comparison of the variables that are monitored after reinforcement(via scanning electron microscopy(SEM)and mercury intrusion porosimetry(MIP))is conducted,and the results further explain the model test results.展开更多
文摘A new triaxial apparatus was designed and manufactured. It is able to applysurcharge and combined vacuum-surcharge pressures on soil samples, and allows for monitoring ofexcess pore-water pressure, axial strain or settlement, and volumetric strain during the process ofconsolidation. Tests were performed using the apparatus on undisturbed soft clayey soil samples,which were collected from Wenzhou, Zhejiang Province, China, at average natural water content 72. 5%. The consolidation behavior of theclay has no rigorous difference, whether it is consolidatedunder the vacuum, surcharge, or combined vacuum-surcharge preloading. The study shows that somephysical properties of the soft clayey soils are changed and mechanical properties are improved tosupport excessive loads transferred to the soil foundation due to construction.
文摘客车制动缸膜板的稳定工作对制动系统的安全性和可靠性具有决定性意义。制动缸膜板直径较大,密封圈处螺栓数量较多且工况复杂,分析表明其安装方式及温度对密封性能影响显著。文中采用有限元分析方法研究顺次加载、ASME PCC-1加载、JIS B 2251加载方式对螺栓预紧力的影响。同时分析了温度变化对螺栓预紧力以及膜板密封面应力分布的影响,并且对制动缸进行了不同温度下的密封性能试验。结果表明,3种加载方式最后都能得到较为均匀的载荷,其中JIS B 2251加载方式最接近目标载荷,加载过程最简易;随着温度的升高,螺栓预紧力上升,密封面上的接触应力增大;低温状态下制动缸内压力下降最快,高温次之,常温最慢。
基金Project supported by the National Key Research and Development Program of China(No.2017YFC0805402)the Open Project of the State Key Laboratory of Disaster Reduction in Civil Engineering(No.SLDRCE17-01),Chinathe National Natural Science Foundation of China(No.51908406)。
文摘This paper presents model tests(macro aspect)and microstructure tests(micro aspect)for investigating the consolidation behavior of Tianjin dredged clay using the prefabricated vertical drain air-booster vacuum preloading(PAVP)and tube air-booster vacuum preloading(TAVP)methods.The mechanism of air-booster vacuum preloading(AVP)using a spring-like system is explained.The main difference between these two methods is the air-boosting equipment.A new anticlogging air-booster prefabricated vertical drain(PVD)is used in the PAVP technique and a self-designed air-booster tube is used in the TAVP technique.In the model tests,a comparison of the variables that are monitored during reinforcement(vacuum pressure,surface settlement,water discharge,and pore-water pressure)and after reinforcement(water content,dry density,and vane shear strength)is conducted.The results indicate that the consolidation behavior of Tianjin dredged clay using the PAVP method is better than that using the TAVP method.PAVP more efficiently mitigates the issue of water-draining PVD clogging and significantly accelerates drainage consolidation.In addition,in the microstructure tests,a comparison of the variables that are monitored after reinforcement(via scanning electron microscopy(SEM)and mercury intrusion porosimetry(MIP))is conducted,and the results further explain the model test results.
