Modified Duncan-chang Model Based On The Mechanics Parameter Test Of Red Clay In Guiyang

A large area land of Guizhou Province is covered by Red clay,which is a high water content, high ductility, high void ratio, low density, compaction and poor regional special clay. The infrastructure construction in Guizhou province such as transportation, construction, met a lot of red clay slope foundation, foundation pit etc. However, it features water sensitivity of losing-water shrink cracks, softening and differential settlement by absorbing water, hard on the soft for the construction of a lot of inconvenience. Meanwhile, compared with other clay, the domestic academic research depth and breadth of red clay is more obviously weak. It is often based on experience gain strength parameters in the Red clay geotechnical engineering calculation. There is a big flaw in the aspect of soil constitutive model.In this paper, abjacent to some stake of the building foundation in Guizhou University Phase II was used to explore the applicability of Duncan- Chang model in Red clay of Guiyang. A series of laboratory consolidated drained triaxial tests is presented on the mechanical parameters of Guiyang Red clay under different water content. In addition, modified the Ducan-Chang model. At last, make a development and verification in the software of FLAC3 D. Specific work in this paper is as follows:(1) Original state samples from excavation site were subjected to a series of conventional laboratory tests, such as basic physical properties, consolidation, consolidated drained triaxial test and etc. Measured the physical property indexes such as the density, moisture content, specific gravity, limit water content, the best indicators water content; mechanics index of void ratio, compressibility, compression modulus, compressive mechanical indicators index, preconsolidation pressure and etc. Based on the results of drained triaxial tests, the damage form, stress-strain curve, the relationships between pore water pressure and displacement changing with the time are analyzed with it in detail.(2) on the basis of the stress-strain curve of original state Red clay, introducing the Duncan-Chang model, fitting1 1 3 1ε/(ζ-ζ) ε curve. According to the piecewise relationship of 1 1 3 1ε/(ζ-ζ) ε curve, modified initial tangent elastic modulus to ingredients section function, established amended Duncan- Chang model of Guiyang Red clay, finaly.(3) Based on the amended Duncan- Chang model, the shear strength parameters, damage ratio, Poisson’s ratio tangent, tangent bulk modulus and other parameters are calculated with it. At the same time, analyze their variation.(4) VC + + programming language is used to improved Duncan-Chang E-B model from Dr. Chen Yu min in software of FLAC3 D. It was corrected by DuncanChang model in the Elastic part. Softening Mohr-Coulomb model and the yield surface stress iterative calculation formula was used to plastic part. It will be achieve the development of Guiyang, Duncan-Chang model of Guiyang Red clay, at the same time, the feasibility and applicability of this model was verified by experimental data.Finally, main research achievements in this paper are summarized, and some further issues in future are put forward. Results of this study not only can enrich the theoretical knowledge of Red clay, but also provide evidence for geotechnical engineering calculations.