循环荷载后围压水对混凝土力学特性影响

Mechanical properties of concrete under confining pressure after cyclic loading

对不同围压(0,2,5,10MPa)下的水饱和混凝土试件,历经25次循环荷载作用后(荷载下限140kN,上限260kN,频率0.1Hz),进行了不同加载速率(地震荷载作用下的混凝土应变速率响应范围10^(-5)/s^10^(-2)/s)下的静动态常三轴抗压性能试验。分析了混凝土峰值应力、峰值应变以及损伤特性。结果表明:历经循环荷载后,随着加载速率的增加,混凝土峰值应力增大,峰值应变整体上逐渐增大,损伤变量D增长速度减缓;随着围压增加,混凝土峰值应力和峰值应变逐渐增大,损伤变量D增长速度降低,但损伤极限差值越来越大。基于上述试验结果,得到了历经荷载循环后混凝土动态峰值应力与围压、加载速率有关的经验计算式及历经荷载循环后混凝土动态峰值应变与围压、加载速率有关的经验式。

After 25 cycles of loads（ the lower limit of load is 140 kN,the upper limit of load is 260 kN,the frequency is 0.1 Hz）,the triaxial compression tests for different confining pressures（ 0,2,5,10 MPa） of water saturated concrete under different loading rates（ the response range of strain rate of concrete under seismic load is 10^（-5）/s ~10^（-2）/s） are carried out,and the peak stress and peak strain of concrete and damage characteristics are analyzed in this study. The analysis results show that after cyclic loading：（1） with the increase of the loading rates,the peak stress and the peak strain of concrete increase gradually,and the growth rate of damage variables slows down;（2） with the increase of the confining pressures,the peak stress and the peak strain of concrete increase gradually. The growth rate of the damage variables is slowing down,but the D-value of damage limit is becoming larger. Based on the experimental results mentioned above,an empirical formula for the dynamic peak stress of concrete with the confining pressures and loading rates after cyclic loading is obtained from the experimental tests.And an empirical formula for the dynamic peak strain of concrete with the confining pressures and loading rates after cyclic loading has also been got based on the above test results.