中文摘要：

为了准确预测岩石类材料复合断裂韧度及裂纹扩展路径，提出结合T应力的修正最大周向应力断裂判据。该修正最大周向应力断裂判据是采用双参数模型（应力强度因子K和T应力）来描述岩石断裂的行为，对岩石类材料复合断裂进行理论计算和实验。结果表明：软岩半圆盘实验所得断裂韧度与传统最大周向应力断裂判据预测结果有较大误差，而修正最大周向应力断裂判据预测结果和实验结果相吻合；当T应力为正并且超过某一定值时，裂纹的扩展路径将发生偏折；T应力对脆性材料断裂试件的断裂韧度和裂纹扩展路径有影响。

英文摘要：

In order to predict the fracture toughness and propagation of the mixed mode fracture of rocks, the modified MTS （Maximum tangential stress） criterion combined with T-stress was presented. The modified MTS criterion uses a two-parameter model （stress intensity factor K and T-stress） to describe the rock＇s fracture. The results ~how that the soft rock with semi-circular specimens is inconsistent with that of the traditional MTS criterion. The modified criterion can provide accurate predictions for the experimental results. The crack will turn when the T-stress becomes positive and at a considerably high value. The T-stress can influence the cracked specimens＇s fracture toughness and the direction of crack＇s propagation.