混凝土三轴蠕变统计损伤模型研究

为探讨混凝土三轴蠕变特性，采用SAM-2000微机控制电液伺服材料三轴试验机并配备压力自平衡式三轴压力室对混凝土进行了三轴压缩试验和三轴蠕变试验，结果表明:围压的存在可以显著提高混凝土的承载能力，围压越大，混凝土的轴向承载能力越高，蠕变变形量和变形速率越小。假设混凝土破坏为其内部微元破坏累积所致，微元破坏概率与混凝土应变存在一定关系P#x003b5；]，且服从Weibull分布，结合三轴压缩试验结果，计算得到了描述混凝土损伤特性的统计损伤变量；基于Burgers流变模型，通过引入损伤变量建立了混凝土三轴蠕变统计损伤模型，利用MATLAB软件进行了模型参数拟合，经对比分析，模型曲线与试验曲线拟合结果较理想，主偏应力越大，拟合结果越精确。此模型可供今后研究参考。

STUDY ON STATISTICAL DAMAGE MODEL OF TRIAXIAL CREEP OF CONCRETE

In order to investigate the triaxial creep characteristic of concrete, a triaxial compression test and a triaxial creep test of concrete were carried out with a SAM-2000 triaxial electronic-hydraulic serve system controlled by a computer. And the results show that the confining pressure can significantly increase the carrying capacity of concrete. The greater the confining pressure is, the higher the axial carrying capacity of concrete would be, while the creep deformation volume and deformation rate change to be smaller, conversely. Assuming that the damage of concrete is caused by the damage accumulation of its internal micro-elements,and there exists a certain relationship P#x003b5;] between the failure probability of micro-elements and the strain of concrete,and the failure obeys the Weibull distribution, the statistical damage variable can be worked out by the triaxial compression test results. Based on the rheological model of Burgers,the statistical damage model of triaxial creep of concrete is established through introducing the damage variable. The model parameters are fitted by MATLAB software, and after a comparative analysis, the fitting results of model curves and test curves come to be more satisfied, and the greater the main deviatoric stress is,the more accurate the fitting results are. This model can be used for a later reference.