棱柱体、圆柱体混凝土的常规三轴试验研究

Conventional triaxial experimental study on prismatic and cylindrical concrete

研制了一种适合在液压室中对棱柱体试样进行常规三轴加载的压头,提出了便捷的试样密封方法;利用该压头对棱柱体混凝土试样进行单轴压缩试验和6档围压下的常规三轴试验。此外,对高强和超高强圆柱体混凝土试样进行单轴压缩试验和5档围压下的常规三轴试验。分析了试样的破坏形态、破坏过程、主裂缝的形成过程与试验曲线之间的对应关系。试验结果表明:(1)该压头密封效果良好;(2)试样的破坏形态分为Ⅰ、Ⅱ、Ⅲ型3种,棱柱体的Ⅱ型破坏形态存在更多的细分种类;(3)当试样的破坏形态为Ⅱ型时,其应力-应变曲线有下降段,曲线εx-εz和εy-εz均存在分离点和直线段,直线段是破坏面两侧块体相对滑动的结果;(4)当试样的破坏形态为Ⅲ型时,其应力-应变曲线是否存在下降段都有可能;但是,当应力-应变曲线无下降段时,破坏形态一定是Ⅲ型的。

An innovative loading head,suitable for conventional triaxial loading of prismatic specimens in the hydraulic chamber,was developed,and facilitated sealing method was also proposed.This loading head was adopted to conduct uniaxial and conventional triaxial tests(under six confinements)on prismatic concrete specimens.In addition,uniaxial and conventional triaxial tests(under five confinements)were also carried out on high-strength and ultra-high-strength cylindrical concrete specimens.The relationships between the failure mode,failure process,main crack formation process and test curve were analyzed.The results indicate that:(1)An excellent sealing performance of developed loading head is well recognized;(2)Failure modes of specimens can be divided into three types(I,II and III),and more subdivision types are observed for prismatic specimens in type II;(3)When the failure mode of specimens is type II,the stress-strain curve has a descending,andεx-εz as well asεy-εz curves both have separation points and straight lines.The straight line is the result of relative sliding of blocks on both sides of the failure surface;(4)When the failure mode of specimens is type III,it is possible that the stress-strain curve has a descending or not.However,the failure mode must be type III when no descending is existed in the stress-strain curve.