On the heavily over-consolidated clay, the yield function with har-dening parameter expressed in isoplastic shearing strain is better than that expressed under failure condition to describe the dilatancy of soil. 对重超固结粘土,采用等塑性剪应变为硬化参数的屈服函数,比用破坏条件的屈服函数更能较好地描述土的剪胀特性。