Study Of Bounding Surface Model For Monotonously And Cyclic Loading On Bias Plane For Concrete

Concrete materials to be hardening or softening for cyclic loading,and non-symmetrical stress cycle will lead to ratchet effect with the scope of plasticity.Concrete show material hardening,material softening,hysteresis,and the volume of material injury,such as expansion of the act for cyclic loading,using the classic plastic models can not simulate the characteristics of these materials.And in the actual tunnel works,the force of the tunnel lining is subject to multi-mode cyclic loading.As a result,passed a lot of reading to the concrete-plastic Theory and the bounding surface model based on Mroz model put forward by both sides in-depth study in order to make improvement,it has been a more satisfied with the two-surface model.This model is a yield surface and a bounding surface,application flow-related laws and regulations and strengthen the rule mixed,the early stage of the loading,stress points in the yield surface to the internal yield surface near the trend of movement,which belong to the elastic deformation stage;when the yield reached the surface after,Began pushing the yield-oriented interface close to the edge until the interface with edges tangent,this process belong to the plastic phase of the load;stress the next point and the beginning of movement back in the other side of the interface with edges tangent,the unloading belonging to the process and Reverse the process to load.This model will be concrete changes in the area is divided into flexible plastic shell and mixed areas,can simulate the image of the concrete under flat and cyclic loading mechanical behavior.Based on this model improved calculation model developed a computer program to calculate the results of tests and the results of a satisfactory agreement for monotonously loading,and it is difficult to simulate mechanical behaviour of concrete for cyclic loading,so the results are little bad.