The Flaw of the Traditional Plastic Potential Theory and the Correction in the Geotechnical Application

摘要

Given the basis that there is no perfect theoretical of the simple and practical geotechnical elastoplastic model which has been set up, triaxial compression test results cannot provide elastic-plastic analytical formula. This article embarks from the basic definition, according to the variation characteristics of micro material under stress, analyses the main reason for traditional plastic potential theory which is not applicable to the geotechnical. Without considering yield stress increasing produce the plastic volumetric strain, plastic work is generally regarded as the plastic potential energy; Postulate of Ilyushin is contrary to the basic hypothesis and ignores the function of the definition of the basic features. Correction method is put forward according to the principle of conservation of energy to define the potential energy of soil plasticity as plastic volume of work done by external force, with the truth of octahedral axis compression plastic potential function instead of Mises's assumption; Natural shear shrinkage, Drucker's inference postulate, dilatancy, by decomposing the plastic volume dilatancy change we get the shear shrinkage, the plastic potential function attached plastic volume expansion line. This kind of research method change Cambridge model to analyze various soil type under axial compression, theoretical derivation and expression is more simple; In reshaping of the shear shrinkage and dilatancy, saturated and unsaturated soil in the application, the results show that: through a correction coefficient of saturated soil and unsaturated soil deformation calculation value, which can effectively describe the triaxial test measurements; Because the triaxial test is widely used in deformation calculation, geotechnical plastic mechanics development towards the direction of the simple and practical is done to explore a new path.