To investigate the frost-heave properties of silty clay under the combination action of seasonal freezing and artificial freezing, and verify the feasibility of combined freezing, eight combined freezing experiments w...To investigate the frost-heave properties of silty clay under the combination action of seasonal freezing and artificial freezing, and verify the feasibility of combined freezing, eight combined freezing experiments were performed on silty clay with water content (mass fraction) of 23.5% and 28.0%, through developed frost-heave test apparatus, in closed or open system. Two sorts of freezing temperature models, namely, constant and sine models, were applied to artificial freezing. The experimental results indicate that the frost-heave degree in seasonal freezing stage accounts for over 90% of the total in open system and it is up to 95% in closed system; the change of artificial sine-freezing temperature has no influence on the frost-heave degree in closed system, however, slight influence in open system. It is found that the variation of temperature gradient of sine-freezing specimen lags behind that of sine-freezing temperature with half phase; sine-freezing temperature model can reduce frost-heave degree of soil. Brand new technology is proposed for the application of artificial ground freezing and new study field of artificial freezing is created.展开更多
The hot deformation behaviors of Cr5 steel were investigated.The hot compression tests were conducted in the temperature range of 900-1150 °C under strain rates of 0.01,0.1 and 1 s^(-1).The constitutive equation ...The hot deformation behaviors of Cr5 steel were investigated.The hot compression tests were conducted in the temperature range of 900-1150 °C under strain rates of 0.01,0.1 and 1 s^(-1).The constitutive equation and material constants(Q,n,α ln A) are obtained according to the hyperbolic sine function and Zener-Hollomon parameter.Besides,dynamic recrystallization(DRX) grain size model and critical strain model are acquired.The processing maps with the strain of 0.1,0.3 and 0.5 are obtained on the basis of dynamic materials model.It has been observed that DRX occurs at high temperature and low strain rate.According to the processing map,the safety region exists in the temperature range of 920-1150 °C with strain rate of 0.01-0.20 s^(-1).展开更多
基金Project(40571032) supported by the National Natural Science Foundation of ChinaProject(2006G011-B-3) supported by Science Studies and Development Plan Foundation of Railway Ministry
文摘To investigate the frost-heave properties of silty clay under the combination action of seasonal freezing and artificial freezing, and verify the feasibility of combined freezing, eight combined freezing experiments were performed on silty clay with water content (mass fraction) of 23.5% and 28.0%, through developed frost-heave test apparatus, in closed or open system. Two sorts of freezing temperature models, namely, constant and sine models, were applied to artificial freezing. The experimental results indicate that the frost-heave degree in seasonal freezing stage accounts for over 90% of the total in open system and it is up to 95% in closed system; the change of artificial sine-freezing temperature has no influence on the frost-heave degree in closed system, however, slight influence in open system. It is found that the variation of temperature gradient of sine-freezing specimen lags behind that of sine-freezing temperature with half phase; sine-freezing temperature model can reduce frost-heave degree of soil. Brand new technology is proposed for the application of artificial ground freezing and new study field of artificial freezing is created.
基金Project(51322405)supported by the National Natural Science Foundation of China
文摘The hot deformation behaviors of Cr5 steel were investigated.The hot compression tests were conducted in the temperature range of 900-1150 °C under strain rates of 0.01,0.1 and 1 s^(-1).The constitutive equation and material constants(Q,n,α ln A) are obtained according to the hyperbolic sine function and Zener-Hollomon parameter.Besides,dynamic recrystallization(DRX) grain size model and critical strain model are acquired.The processing maps with the strain of 0.1,0.3 and 0.5 are obtained on the basis of dynamic materials model.It has been observed that DRX occurs at high temperature and low strain rate.According to the processing map,the safety region exists in the temperature range of 920-1150 °C with strain rate of 0.01-0.20 s^(-1).
