混凝土结构I型裂纹裂尖塑性区研究

CRACK TIP PLASTIC ZONE OF TYPE I CRACKS FOR CONCRETE STRUCTURE

应用双剪统一强度理论,研究了I型裂纹的塑性变形问题。给出了包含反映材料拉压性能差异的参数拉压比及反映中间主应力效应的参数b的I型裂纹裂尖塑性区形状和大小的统一解。已有的Tresca准则、Mises准则和Mohr-Coulomb准则解均是本文的特例或线性逼近。针对混凝土结构,画出了不同参数b情况下的裂尖塑性区半径变化图。得出了材料拉压比对I型裂纹裂尖塑性区影响很大。b对I型裂纹裂尖塑性区影响随拉压比的不同而不同,拉压比较大时,b对塑性区影响大,拉压比较小时,b对塑性区影响小的结论。该统一解可以适应于各种不同材料,能充分发挥材料潜力,具有普遍性和广泛的适应性,有一定的工程应用价值。结论对于研究各种材料的断裂问题有参考作用。

The unified solutions for the shape and size of mode I crack tip plastic zone are obtained based on the twin shear unified strength theory. The strength difference effect （SD Effect） and the intermediate principal stress effect are all included in the solutions. Former solutions for this problem using Tresca criterion, von Mises criterion, and Mohr-Coulomb criterion are special cases or linear approximations of this solution. The shape and radius of crack tip plastic zone of type Ⅰ cracks for concrete structure is given in this paper. It can be found that tension-compression strength ratio has obvious effect on the plastic zone of mode I crack tips. The influence of the parameter b,which reflects the intermediate principal stress, has stronger influence on the plastic zone as the tension-compression strength ratio is larger and vice verse. This solution is applicable to various types of materials and of important practical value.