不同围压下C60混凝土三轴压缩过程能量分析

Energy analysis of C60 concrete under triaxial compression under different confining pressures

针对复杂应力状态下高强混凝土受压变形破坏过程中的能量演化机制问题,开展不同围压下C60高强混凝土试样三轴压缩试验,分析其在受力全过程中的变形与破坏特征。根据试验结果,探究了不同围压下高强混凝土三轴压缩过程能量演化机制。研究结果表明:围压越大,混凝土试样破坏时,其峰值应力与峰值应力对应的轴向应变越大,破坏形式由张拉破坏向剪切破坏过渡;峰值应力前,混凝土试样主要以弹性应变能储存为主,峰值应力对应的输入能密度和耗散能密度均随围压的增大而增大,且均与围压满足指数函数关系,其形状改变系数FX与轴向应力呈正比关系,体积改变系数FV与轴向应力呈反比关系;达到峰值应力时,体积改变系数FV小于形状改变系数FX;峰值应力后,主要以弹性应变能释放为主,并随着混凝土试样的破坏转化为各种形式的能量耗散。研究结果可为今后从能量角度研究高强混凝土本构关系提供有益参考。

Aiming at the problem of the energy evolution mechanism of high-strength concrete under complex stress state during the process of compression deformation and destruction, triaxial compression tests were carried out on C60 high-strength concrete samples under different confining pressures, and the characteristics of deformation and destruction during the whole stressing process are analyzed. According to the test results, the mechanism of energy evolution of high-strength concrete during triaxial compression under different confining pressures is explored. The results of the study indicate that the greater the confining pressure, the greater the peak stress of the concrete specimen during failure and the greater the axial strain corresponding to the peak stress. The failure mode is from tension-shear failure to shear failure. Before reaching the peak stress, the concrete sample mainly stores elastic strain energy. Both of the input energy density and the dissipated energy density corresponding to the peak stress increase with the increase of confining pressure, and both satisfy the exponential function relationship with the confining pressure. The shape change factor FX is proportional to the axial stress, and the volume change factor FV is inversely proportional to the axial stress. When the peak stress is reached, the volume change factor FV is smaller than the shape change factor FX. After reaching the peak stress, it mainly releases elastic strain energy and the energy dissipates into various forms of energy with the destructing of the concrete specimen. The research results provide a useful reference for studying the constitutive relationship of high-strength concrete from an energy perspective.