真实水荷载对混凝土强度影响的试验研究

Effect of water loading on strength of concrete

为了了解混凝土材料在水环境中的力学性能,本文试验研究了混凝土在水中及三轴应力状态下的抗压强度特性。试验在大型多功能静动三轴仪上进行,混凝土试件采用Φ100mm×200mm圆柱体试件,试验中考虑了不同的水荷载作用方式、围压和湿度含量的影响。试验的水荷载作用方式分为机械围压(试件密封)和真实水围压(试件不密封)两种。围压大小分别为0、2和4MPa。为了确定湿度对混凝土强度的影响,进行了干燥和饱和两种湿度混凝土的三轴压缩试验,并进行对比。试验研究表明,试件密封条件下,干燥和饱和混凝土的强度均随围压增加且效应明显,但干燥混凝土比饱和混凝土的围压效应更显著;在试件不密封条件下,混凝土三轴强度比密封条件下的强度低。试件不密封条件下,饱和混凝土的三轴强度接近其单轴强度,但干燥混凝土强度降低较大。文中还基于混凝土内部孔隙水压力和外部水荷载的相互作用机理,对试验结果进行了初步解释。

The effect of water on concrete compressive strength subjected to triaxial stress was experimentally studied. The cylindrical specimens were 200mm high with diameter 100mm, and the test was carried out by using a static triaxial test machine. The effects of the way of water loading, the confining pressure and the moisture of concrete were taken into account. Two ways of water loading were adopted. In the first way, the confining pressure of water was exerted on specimens mechanically and specimens were sealed to prevent from the penetrating of water. In the second way, specimens were really subjected to water loading and exposed to high water pressure directly. The confining pressure was in the range from 0 to 4 MPa. The tests were carried out both for dry and saturated specimens. The results indicate that under the condition of specimens being sealed, the compressive strength of both dry and saturated concrete under triaxial stress increases obviously with the increase of the mechanical confining pressure, especially for dry concrete. Whereas, under the condition of unsealed the strength of dry concrete decrease remarkably, and the strength of saturated concrete is approximately equal to its uniaxial compressive strength and external loading . Furthermore, the mechanism of the interaction between pore pressure of concrete are demonstrated.