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
Effects of Zn, Zn-Al and Zn-P additions on melting points, microstructures, tensile properties, and oxidation behaviors of Sn-40 Bi lead-free solder were investigated. The experimental results show that the addition o...Effects of Zn, Zn-Al and Zn-P additions on melting points, microstructures, tensile properties, and oxidation behaviors of Sn-40 Bi lead-free solder were investigated. The experimental results show that the addition of these three types of elements can refine the microstructures and improve the ultimate tensile strength（UTS） of solder alloys. The fractographic analysis illustrates that ductile fracture is the dominant failure mode in tensile tests of Sn-40Bi-2Zn（SBZ）and Sn-40Bi-2Zn-0.005Al（SBZA） specimens, while brittle fracture is the controlled manner in Sn-40Bi-2Zn-0.005P（SBZP） and Sn-58 Bi solders. XPS analysis indicates that trace amounts of both Al and P additives in solder can improve the antioxidant capacity, whereas only the additive of Al in solder can reduce the thickness of oxidation film.展开更多
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.
基金financially supported by the Natural Science Fund for Colleges and Universities in Jiangsu Province (Nos. 11KJB460003 and 12KJB460003)Jiangsu Planning Project of Science and Technology (No. SBK201241936)National Natural Science Foundation of China (No. 51201072)
文摘Effects of Zn, Zn-Al and Zn-P additions on melting points, microstructures, tensile properties, and oxidation behaviors of Sn-40 Bi lead-free solder were investigated. The experimental results show that the addition of these three types of elements can refine the microstructures and improve the ultimate tensile strength（UTS） of solder alloys. The fractographic analysis illustrates that ductile fracture is the dominant failure mode in tensile tests of Sn-40Bi-2Zn（SBZ）and Sn-40Bi-2Zn-0.005Al（SBZA） specimens, while brittle fracture is the controlled manner in Sn-40Bi-2Zn-0.005P（SBZP） and Sn-58 Bi solders. XPS analysis indicates that trace amounts of both Al and P additives in solder can improve the antioxidant capacity, whereas only the additive of Al in solder can reduce the thickness of oxidation film.
