真三轴应力下塑性混凝土的变形与强度  

Deformation and Strength of Plastic Concrete under True Triaxial Stress

作　　者：王四巍[1] 张晨[1] 李常虎[2] 

机构地区：[1]华北水利水电大学岩土工程与水工结构研究院,河南郑州450045 [2]中国电力建设集团有限公司西北勘测设计研究院有限公司,陕西西安710065

出　　处：《建筑材料学报》2016年第4期637-641,646,共6页Journal of Building Materials

基　　金：国家自然科学基金资助项目(51109082);河南省基础与前沿技术研究计划项目(142300413216);河南省高等学校青年骨干教师计划资助项目(2013GGJS-083)

摘　　要：通过侧压恒定和侧向位移近似恒定的2类真三轴压缩试验,研究了三向应力下塑性混凝土的变形、破坏和强度.在侧压恒定的真三轴试验条件下,塑性混凝土侧压从0至设定值过程中产生了压缩变形,此后,侧向应力和应变均保持稳定,侧向由压缩变形转变为膨胀变形,但侧向应力大小稳定,塑性混凝土强度与侧向应力大小密切相关;在侧向位移近似恒定的真三轴试验条件下,侧压随着轴压增加而增大,强度可达单轴强度9倍以上.塑性混凝土在真三轴压缩作用下的变形过程为:在轴向应力-应变曲线上,轴向压缩初期至直线上升段,侧向在侧压作用下产生变形,约束阻止了膨胀变形的过早出现,延迟了膨胀变形的产生,提高了最大体积压缩值,增强了试件的抗裂性能,提高了轴向抗压缩变形能力,增大了强度;当轴向压缩达到一定程度时,侧向变形由压缩转变为膨胀,体积很快压缩至最小,抗压强度也很快达到峰值;之后,轴向变形加速发展,膨胀变形由于侧向约束而发展较慢,轴向应力缓慢下降.在单轴作用下,峰值后轴向压缩加速发展,膨胀变形由于无约束而快速发展,轴向应力快速下降.Deformation and strength of plastic concrete were studied by two kinds of true triaxial compres- sion test. Lateral pressures are constant in first kind of test, and they were compressive prepeak and expan- sive postpeak, and strength is effected by the lateral pressures. In the second kind of test, those are in- creasing with increase of axial pressure and the strength was 9 time those of the uniaxial compressive one. The failure mechanism of plastic concrete under true triaxia] compressive stress is as follows： When axial stress applied, lateral deformation is compressive because of constraint, and it retarde the appearance of expansive deformation, enhance anti-racking performance. When axial compressive deformation is large enough, and lateral compressive deformations chang to expansive, and the volume tend to the minimum, and the strength reaches the peak quickiy, but axial stress reduces slowly because lateral constraints. While axial compressive deformation accelerates after peak under the uniaxial compressive tests, axial stress reduces quickly without lateral constraints.

关 键 词：塑性混凝土 真三轴试验 变形 应力-应变曲线 强度 

分 类 号：TV148[水利工程—水力学及河流动力学]