基于PFC3D的超固结非饱和黏性土力学特性分析

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中图分类号：TU432 文献标志码：A

Abstract：In order to further study the mechanical properties of the overconsolidated unsaturated clay and conduct true triaxial numerical tests to verify the proposed triple-shear subloading surface models for the overconsolidated unsaturated clay，the overconsolidated axis and true triaxial test models under flexible film conditions were established byusing PFC3D softwareand Hillcontact model，taking Jiangxi clayas the research object.The particle flow numerical simulation study was carried out on the static and dynamic cyclic triaxial tests under different matrix suction，overconsolidation degree and stress amplitude.The evolution law of the stress-strain relationship and other macroscopic mechanical characteristics of the overconsolidated unsaturated clay sample were obtained.The changes of the contact force chain and displacement field during shear were analyzed from the microscopic perspective.The results of PFC3D numerical simulation were compared with the results of conventional static and dynamic triaxial consolidation drainage tests of overconsolidated unsaturated clay.The results show that the simulation values of particle flow software are consistent with the experimental results，and can reflect the mechanical properties of overconsolidated unsaturated clay，such as strain softening，dilatancy，ratchet effect and Mansing effct under dynamic load. The applicability of the particle flowmodel calculation program to simulate the basic mechanical characteristics of overconsolidated unsaturated clay such as stress and strain is verified，and the numerical test can be carriedout，indicating that the particle flowmodel can replace the laboratory test of overconsolidated unsaturated clay under various complexloading conditions.The particle flow model is used as a digital testing machine instead of the true triaxialtest inthe laboratory to verifythe theoreticalresultsof the triple-shear loading surface model of the overconsolidated unsaturated clay.The results show that the results of constitutive theory are basically consistent with those of PFC3D numerical simulation. Compared with Bishop stress variable method，Fredlund stress variable method is closer to PFC3D simulation resultsand has smaller errors.

Key words： overconsolidated unsaturated clay；PFC3D numerical test；Hill contact mode;cyclic load; Jiangxi clay

超固结非饱和黏性土在循环荷载作用下，其动力特性主要受基质吸力和超固结程度的影响。（剩余16609字）