不同水压力下混凝土水力劈裂扩展阻力分析

Analysis of hydraulic crack propagation resistance of concrete under different water pressures

基于水力裂缝扩展准则,建立混凝土三点弯曲梁水力劈裂断裂过程反演分析模型,进而获得混凝土水力裂缝扩展阻力计算方法。利用混凝土三点弯曲梁水力劈裂测试方法,开展了15组初始水压力为0~0.5 MPa的混凝土水力劈裂试验,反演分析了各组试验的水力劈裂扩展过程,进而计算得不同水压力下裂缝的扩展阻力。研究结果表明:提出的计算模型可以准确反演水力裂缝的扩展过程,计算得混凝土梁P-CMOD曲线与实测曲线的误差小于10%;不同水压力下混凝土水力裂缝的扩展阻力变化规律基本相近,当水压力由0 MPa增加至0.3 MPa,裂缝扩展阻力降低明显,当水压力由0.3 MPa增加至0.5 MPa,裂缝扩展阻力的变化较小。这表明环境水压力会降低混凝土水力劈裂的抗裂性能,但是在低水压力条件下该效应的影响有限。

Based on the hydraulic crack propagation criterion in concrete,an inverse analysis model for the hydraulic fracturing process of three-point bending concrete beams was established.Then a calculation method for the hydraulic crack propagation resistance of concrete was obtained.Hydraulic fracturing tests of 15 concrete beams with initial hydraulic pressures ranging from 0 MPa to 0.5 MPa in the crack were conducted.The hydraulic crack propagation processes of all beams were inversely ana lyzed and the crack propagation resistance were calculated.Results showed that,the proposed calculation model has a good performance in inverting the hydraulic fracture propagation process of concrete beam,and the error between the calculated P-CMOD curves and the measured P-CMOD curve was less than 10%.The variation law of the resistance of hydraulic crack propagation in concrete under different water pressures was basically similar.The crack propagation resistance decreased significantly with the initial water pressure increased from 0 MPa to 0.3 MPa,while the change in crack propagation resistance was small with the water pressure increased from 0.3 MPa to 0.5 MPa.This indicates that water pressure reduces the crack resistance of the concrete under hydraulic fracturing,but the effect is limited within low water pressure.