Artificially cemented soils have been widely used as filling materials in highway and railway construction.The shear strength evolution of filling materials upon moist variation can determine the stability of subgrade...Artificially cemented soils have been widely used as filling materials in highway and railway construction.The shear strength evolution of filling materials upon moist variation can determine the stability of subgrade and embankments.This study conducted water retention tests,MIP tests,and multi-stage triaxial shear tests on cement-treated granite residual soil(GRS)to determine its water retention curve(WRC)upon free drying,pore structure,and peak shear strength qf,respectively.The water retention behavior and shear strength evolution upon free drying were modeled based on the dual-porosity structure of cement-treated GRS and the effective stress principle,respectively.Results show that the drying-WRC is bimodal and higher cement dosage yields a more severe decrease in the water retention capacity within a specific suction range.For a given confining pressure,the peak shear strength qf increased with increasing cement dosage or suction value s.The peak shear strength qf also solely depends on the suction value in the peak stress state.In addition,the cement-treated GRS has a bimodal pore size distribution curve,and its macro-and micro-void ratios remain almost unchanged after free drying.The bimodal drying-WRC of the cement-treated GRS can be modeled by differentiating the water retention mechanisms in macro-and micro-pores.Moreover,using the macro-pore degree of saturation as the effective stress parameterχ=S_(rM),the q_(f)–p′_(f)relationship(where p′_(f)is the effective mean pressure at failure)under various suction and stress conditions can be unified,and the q_(f)–s relationships at various net confining pressuresσ_(3),net can be well reproduced.These findings can help design subgrade and embankments constructed by artificially cemented GRS and assess their safe operation upon climate change.展开更多
The behaviors of lead zirconate titanate （PZT） deposited as the dielectric for high-voltage devices are investigated experimentally and theoretically. The devices demonstrate not only high breakdown voltages above 3...The behaviors of lead zirconate titanate （PZT） deposited as the dielectric for high-voltage devices are investigated experimentally and theoretically. The devices demonstrate not only high breakdown voltages above 350 V, but also excellent memory behaviors. A drain current–gate voltage （ID-VG） memory window of about 2.2 V is obtained at the sweep voltages of ±10 V for the 350-V laterally diffused metal oxide semiconductor （LDMOS）. The retention time of about 270 s is recorded for the LDMOS through a controlled ID-VG measurement. The LDMOS with memory behaviors has potential to be applied in future power conversion circuits to boost the performance of the energy conversion system.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos.52379104,42202298)Joint fund of National Natural Science Foundation of China-Railway Corporation for basic research of high-speed railway (Grant No.U1934208).
文摘Artificially cemented soils have been widely used as filling materials in highway and railway construction.The shear strength evolution of filling materials upon moist variation can determine the stability of subgrade and embankments.This study conducted water retention tests,MIP tests,and multi-stage triaxial shear tests on cement-treated granite residual soil(GRS)to determine its water retention curve(WRC)upon free drying,pore structure,and peak shear strength qf,respectively.The water retention behavior and shear strength evolution upon free drying were modeled based on the dual-porosity structure of cement-treated GRS and the effective stress principle,respectively.Results show that the drying-WRC is bimodal and higher cement dosage yields a more severe decrease in the water retention capacity within a specific suction range.For a given confining pressure,the peak shear strength qf increased with increasing cement dosage or suction value s.The peak shear strength qf also solely depends on the suction value in the peak stress state.In addition,the cement-treated GRS has a bimodal pore size distribution curve,and its macro-and micro-void ratios remain almost unchanged after free drying.The bimodal drying-WRC of the cement-treated GRS can be modeled by differentiating the water retention mechanisms in macro-and micro-pores.Moreover,using the macro-pore degree of saturation as the effective stress parameterχ=S_(rM),the q_(f)–p′_(f)relationship(where p′_(f)is the effective mean pressure at failure)under various suction and stress conditions can be unified,and the q_(f)–s relationships at various net confining pressuresσ_(3),net can be well reproduced.These findings can help design subgrade and embankments constructed by artificially cemented GRS and assess their safe operation upon climate change.
基金the National Basic Research Program of China(Grant No.50772019)the National Natural Science Foundation of China(Grant No.61204084)
文摘The behaviors of lead zirconate titanate （PZT） deposited as the dielectric for high-voltage devices are investigated experimentally and theoretically. The devices demonstrate not only high breakdown voltages above 350 V, but also excellent memory behaviors. A drain current–gate voltage （ID-VG） memory window of about 2.2 V is obtained at the sweep voltages of ±10 V for the 350-V laterally diffused metal oxide semiconductor （LDMOS）. The retention time of about 270 s is recorded for the LDMOS through a controlled ID-VG measurement. The LDMOS with memory behaviors has potential to be applied in future power conversion circuits to boost the performance of the energy conversion system.
