塑性混凝土双轴受压性能与破坏准则

Performance and failure criteria for plastic concrete under biaxial compressive stress

基于塑性混凝土立方体试件的双轴压缩试验,研究了塑性混凝土的双轴受压性能和破坏准则。结果表明：当应力比较小时,塑性混凝土双轴受压破坏形态与单轴受压相似;随应力比增加,双轴受压破坏面龟裂现象明显;双轴受压下的塑性混凝土抗压强度显著提高,是单轴抗压强度的1.77-4.72倍;随应力比的增大,塑性混凝土抗压强度先增大后减小,应力比0.75时抗压强度的提高最大;单轴抗压强度越高,双轴受压时塑性混凝土抗压强度的增长越小。塑性混凝土八面体正应力应变曲线、剪应力应变曲线的斜率随应力比的增加有增大的趋势,其变形随抗压强度的增加有所降低。双轴受压各应力比下的八面体剪应力与正应力之间均具有线性关系,其斜率随应力比的增加逐渐降低。通过对试验结果的分析,建立了双轴受压下塑性混凝土抗压强度的包线方程以及双参数、三参数及考虑加载路径影响的破坏准则。

Based on biaxial compression test of cubic specimens,the performance and failure criteria forplastic concrete were discussed.The results indicate that the failure mode is similar to that of axial com-pression when the ratio of both biaxial stresses is little,and the most serious damaged surface is of obvi-ously crevasse crack when the ratio is large.The biaxial compressive strength of plastic concrete is extraor-dinary enhanced to 1.77 to 4.72 times as much as the axial compressive strength.The biaxial compressivestrength of plastic concrete first increases and then decreases with the increasing of stress ratio,and is upto its maximum when the stress ratio reaches about 0.75.The larger the axial compressive strength of plas-tic concrete,the less increase the biaxial compressive strength.With the stress ratio increases,the slopeof octahedral normal stress strain and octahedral shear stress-strain curve has an increasing trend.The biaxi-al deformation decreases with the increase of compressive strength.There is an obvious linear relationshipbetween octahedral shear stress and normal stress under each stress ratio,but its slope gradually decreaseswith the increase of stress ratio.Based on the analysis for test results of plastic concrete under biaxial com-pression test,the strength envelope equation and the failure criteria with double parameters,three parame-ters and considering the impact of load paths were established for plastic concrete under biaxial stresses.