沿应变路径准静态加载时混凝土的极限状态现象

为了研究混凝土的力学行为，利用电液伺服系统实验机对立方体试块沿着应变空间中的偏平面压缩路径进行了三轴加载试验．试验结果表明：混凝土材料在应力空间中存在有一个极限状态曲面，当沿着应变路径进行加载时，应力状态点的运动轨迹最后总是汇集到该曲面上，极限状态曲面与应力空间中的破坏面重合．在平均应力p与广义剪应力q构成的直角坐标系中，P轴上存在两个临界值，把p轴划分成低压区、中压区和高压区．当应变路径起点对应的p在同一区内时，p-q曲线彼此相似，在不同区时曲线有一定差异．极限状态现象可能引导研究者建立起一种混凝土特有的新的本构关系理论框架．

Phenomena of Concrete Limit State Under Qqasi-Static Loading Along Strain Paths

For the benefit of improved understanding of constitutive behavior of plain concrete, the tests were performed on cubic specimens under quasi-static loading along the path on deviatoric plane of principal strain space with hydraulic servo triaxial testing apparatus. Test results revealed that there is a limit state surface in principal stress space, coinciding with failure surface, to which the points of stress state would always move when loading the specimens along the strain paths. In the Cartesian coordinate system with axis lines p （mean stress） and q （generalized shear stress）, p axis is divided into three segments： the low, the medium and the high pressure segment, with two critical values. The p-q curves, i.e. the lines produced by moving points of stress state, are similar to each other when their starting points are in the same segments, and they are different when theirs are not. The above are the phenomena of limit state which may contain some clues for researcher to set up a new frame- work of constitutive relation for concrete.