混凝土超低温力学特性及本构关系研究

Study on the Mechanical Properties and Constitutive Relations of Concrete Under Cryogenic Circumstance

本工作针对全混凝土液化天然气(LNG)储罐服役期间面临的超低温环境(-165℃)问题,配制了一种高强耐超低温混凝土(LHC)。对不同低温LHC和普通C60混凝土进行单轴和三轴压缩试验,得出了LHC和C60混凝土的强度变化规律。借助双参数本构模型,表征了应力和温度耦合作用下LHC和C60混凝土的变形特性。结果表明,在单轴压缩试验中,随着温度的降低,LHC的强度从65.3 MPa(20℃)增长到96.2 MPa(-165℃);普通C60混凝土的强度先增加后降低,在-140℃时达到最大值78.1 MPa;LHC和C60的延性均随温度降低呈波动下降趋势。在三轴应力状态下,LHC和C60的强度和延性均随温度的降低有所增大。两组试验条件下,LHC均比普通C60混凝土具有更优异的低温力学性能。本研究可以为LHC在全混凝土液化天然气储罐的应用提供参考。

To solve the problem of cryogenic circumstance(-165℃)faced by all-concrete liquefied natural gas(LNG)storage tanks during service,a low-temperature resistant and high-strength concrete(LHC)was formulated.The compressive strength change laws of LHC and ordinary C60 concretes were obtained through the uniaxial and triaxial compression tests under different low temperature conditions.A two-parameter constitutive model was adopted to characterize the deformation characteristics of LHC and C60 concrete under the combined effect of stress and temperature.The test results show that the strength gradually increases as the temperature decreases in the uniaxial test,and the strength of LHC increases from 65.3 MPa(20℃)to 96.2 MPa(-165℃);the strength of ordinary C60 concrete increases first and then decreases,reaching the maximum value of 78.1 MPa at-140℃;the ductility values of LHC and C60 both fluctuate and decrease with the drop of temperature.Under triaxial stress,the strength and ductility of LHC and C60 increase with the drop of temperature.Under the two sets of test conditions,LHC has better cryogenic mechanical properties than ordinary C60 concrete.The research results of this study can provide reference for the application of LHC in all-concrete LNG storage tanks.