循环孔隙水压下混凝土常规三轴压缩损伤破坏特性分析

Damage Property Analysis of Concrete Subjected to Conventional Tri-axial Compression under Cyclic Pore Water Pressure

本文进行了孔隙水压不同循环次数(0次,10次,50次,100次和200次)以及不同应变速率下(10^(-5)/s,10^(-4)/s,10^(-3)/s和10^(-2)/s)混凝土常规三轴压缩试验,分析了混凝土峰值应变的变化规律、应力-应变曲线及损伤特性。结果表明:相同循环次数孔隙水压下,峰值应变随应变速率增加,整体呈现出增加的趋势;而相同应变速率下,峰值应变随孔隙水压循环次数的变化规律并不明显;在中低应变速率(10^(-5)~10^(-3)/s)下,混凝土的损伤变化受孔隙水压循环次数影响较大;当循环次数达到200次时,孔隙水压作用对混凝土产生较大的损伤。通过对循环孔隙水作用下混凝土动态损伤破坏机理的分析可知:混凝土的破坏过程实际上是内部裂纹不断形成、扩展、贯通,材料损伤不断产生、累积的过程;当损伤达到一定程度,混凝土发生宏观破坏,失去承载力。

Conventional tri-axial compression experiment of concrete was carried out at different strain rates（10^（-5）/s,10^（-4）/s,10^（-3）/s and 10^（-2）/s）and with different numbers of cycle of pore water pressure（0,10,50,100 and 200times）,respectively;peak value variation of concrete strain,stress-strain curve and damage characteristics were analyzed.Results show that with the same number of cycles of pore water pressure,the peak values of strain entirely present an increasing trend with the increase of strain rate;while at the same strain rate,the variation of peak strain is not obvious with the variation of cycle numbers of pore water pressure.At low and medium strain rates（10^（-5）~10^（-3）/s）,number of cycles of pore water pressure has larger impact on concrete damage.When the number of cycles reaches up to 200 times,pore water pressure produces larger damage of concrete.Through the analysis of dynamic damage and failure mechanism of concrete subjected to cyclic pore water action,it is known that the destruction process of concrete is actually the formation,expansion and penetration of internal cracks,and also is a process of generation and accumulation of damage.When damage reaches a certain level,macroscopic damage of concrete happens,and concrete loses bearing capacity.