Considering the anisotropic behaviour of natural clay the new constitutive model employs an inclined ellipse as the yield surface, no longer the aclinic ellipse used in traditional modified Cam-clay.

• 由此，本文首先根据天然软粘土的屈服性状，将修正剑桥模型各向同性的屈服面改进为各向异性的椭圆屈服面；