对混凝土构件来说,在平面问题中I、II型复合裂纹甚为常见.对于复合型裂纹的失稳扩展,目前已有最大拉应力理论、能量释放率理论和应变能密度理论等,并都有其相应的断裂判据.此外,也可用边界配位法或有限元法对复合型裂纹的应力强度因子进行计算.但是,有关混凝土的复合裂纹问题,尚未见到资料. For concrete components, type I and type II composite cracks are very common in plane problems. For the instability expansion of composite cracks, there are currently the maximum tensile stress theory, energy release rate theory, and strain energy density theory, etc. There are corresponding fracture criteria. In addition, the boundary strength method or finite element method can also be used to calculate the stress intensity factor of the composite crack. However, the composite crack problem of concrete has not been seen yet.