混凝土裂缝面压力对其深度测试结果的影响研究

在混凝土结构中,其应力状态随着荷载、温度等条件的不同会发生相应的变化。对混凝土结构中裂缝深度的无损检测,必须考虑裂缝面的应力状况,特别是深裂缝,其裂缝面上应力状况的影响则更加显著。利用大型混凝土块试验,比较在不同应力条件下,几种代表性的无损检测方法的测试结果。结果表明:当裂缝面上承受微小压应力时,"相位反转法"和"传播时间差法"均不能正确地测试裂缝深度;而当裂缝面上的压应力超过5 MPa时,现目前使用的检测方法都无法合理地测出裂缝的深度。因此,在检测裂缝深度时,需要密切关注裂缝面上的应力状态,同时,通过"表面波法"得到的裂缝深度测试结果的变化,间接地推测裂缝面上应力状态,为结构的分析提供相应依据。

STUDY ON THE IMPACT OF CONCRETE CRACK SURFACE PRESSURE ON THE DEPTH TEST RESULTS

In the concrete structure,the stress may change with load and tempercture etc.For crack depth testing by NDT methods,the stress condition of crack surface must be considered,especially for deep crack.In this paper,the results by large concrete block test were got.It was compared the difference between several representative nondestructive testing methods at the different stress conditions.The results show that the tested crack depth may be underestimated seriously by "phase inversion method"and "propagation time method",and the "surface wave method" performs better when the compressive stress on the crack surface is equal to,or less than 5 MPa.