多类混凝土和各向同性岩石损伤比强度准则

Damage ratio strength criterion for various types of concrete and isotropic rock

针对已有损伤比变量下的损伤比强度理论仅适用于混凝土且偏平面略有内凹等不足,基于多轴应力下混凝土损伤比强度理论的一般形式,根据已有试验资料关于普通混凝土、再生骨料混凝土、轻骨料混凝土和各向同性岩石破坏包络面的特征,建议考虑Lode角和静水压力对受压损伤比影响以及考虑材料类型对受拉损伤比影响的六参数损伤比变量表达式,且损伤比变量取值得到单轴、二轴和三轴受力状态下混凝土和单轴受力状态下各向同性岩石应力-应变曲线试验结果的验证。通过与国内外397组混凝土、130组再生骨料混凝土、97组轻骨料混凝土、179组单轴抗压强度小于100MPa的岩石(用"岩石Ⅰ类"表示)和165组单轴抗压强度大于100MPa的岩石(用"岩石Ⅱ类"表示)多轴强度试验资料的比较,表明考虑Lode角和静水压力后的六参数损伤比强度准则与相对应材料的三维破坏包络面精度较高。此外针对二轴应力状态,提出了进一步简化的损伤比强度准则。

The existing damage ratio strength theory utilizing damage ratio variable is only applicable to concrete with the disadvantage of concave deviatoric plane loci under high hydrostatic pressure.To extend its application scope and treat with the deficiency, based on the general form of the damage ratio strength theory for concrete, a six-parameter expression of the damage ratio variable was proposed according to the characteristics of the failure envelope for concrete, recycled aggregate concrete, lightweight aggregate concrete and isotropic rock.In the proposed expression, the effects of Lode angle and hydrostatic stress on the compressive damage ratio and the effect of material type on the tensile damage ratio were taken into account.Furthermore, the values of damage ratio variable obtained by the proposed expression were verified based on the existing experimental stress-strain curves of concrete under uniaxial, biaxial and triaxial stress states and those of isotropic rock under uniaxial stress states.By comparing the predicted results to the experimental data of concrete(397 specimens), recycled aggregate concrete(130 specimens), lightweight aggregate concrete(97 specimens), "rock of type I"(179 specimens with uniaxial compressive strength f_(c)<100 MPa) and "rock of type II"(165 specimens with f_(c)>100 MPa), the modified criterion using six-parameter damage ratio variable can represent the corresponding characteristics of the failure envelope of aforementioned materials with high accuracy.In addition, for the materials under biaxial stress states, simplified damage ratio strength criterion curves were proposed as well.