混凝土双K断裂参数计算理论及规范化测试方法

就其课题组在双K方法方面取得的最新进展进行了汇报。结合当前由Hillerborg,Shah,Karihaloo,Bazant,Elices等学者及其合作者提出的各种断裂模型的优点，在双K方法中，提出了双K断裂准则并引入了相应的断裂参数KIc^ini，KIc^un和CTODc，该准则的优点在于，既考虑了分布在软化过程区的粘聚力，又以可供解析分析的应力强度因子参量作为表现形式。根据双K方法，在计算中，中需采用标准三点弯曲缺口梁、紧凑拉伸和楔入劈拉单一尺寸试件上进行简单的试验，无需卸载，且只要测定P－CMOD曲线上升段的初始柔度ci以及通过最大荷载的割线柔度Cs作为计算的输入数据，所有的计算都可在小型计算器上解析运行，而不必进行非线性方程求解、数值积分及回归分析。该双K断裂参数的计算方法在理论基础方面较为系统和完备，实验方法简便，可作为建立我国混凝土断裂参数规范化标准测试方法的参考草案。

The Calculation Approaches of Double-K Fracture Parameters of Concrete and a Possible Coding Standard Test Method for Determining Them

In this report,the author reported the recent development on the double K method achieved by his research team.In this method the double K fracture criterion is proposed the corresponding double K fracture parpameters including K ini Ic , K un Ic and CTOD c are introduced.This method combines the advantages of various current fracture models proposed by Hillerborg,Shah,Karihaloo,Bazant,Swartz,Elices and their co researchers.The criterion considers the cohesive force along the softening process zone and is termed the stress intensity factor.According to the double K method,simple tests are required to be carried out on a standard three point bending notched beam,compact tension specimen and wedge splitting specimen with a single size without unloading reloading procedure.One needs only to measure the initial compliance c i and the secant compliance c s through the peak load on the ascending branch of a P CMOD curve as the input testing data in the calculation.All calculations can be analytically performed with a pocket calculator,without solving nonlinear equations,numerical integrations and regression analysis.It could lead to a recommendation or a standard testing method to determine the double K fracture parameters