Research On Parameters Of Cambridge Model For Reticulate Red Clay

Reticulate red clay is familiar in geotechnical construction around Dongting Lake and so far people have paid much attention to the origin, distribution, structure and elastic deformation of reticulate red clay. As one of the typical elastic-plastic models, Cambridge Model is applied widely, while there is no research about applying of Cambridge Model in reticulate red clay. It’s important to use Cambridge Model to describe the reticulate red clay so as to confirm whether Cambridge Model can be used in numerical analysis of reticulate red clay around Dongting Lake. Based on the achievements of the previous studies, a series of laboratory tests were made and main achievements were presented in this dissertation, obtained by theoretical analysis of the results of the tests as follows:(1)A series of CD and CU triaxial tests were performed for remodeled reticulate red clay around Dongting Lake. The deformation and stiffness strengh characteristics of reticulate red clay were revealed in detail. The test results show that the stress-strain relations of CD triaxial tests behave as strain hardening type and CU triaxial tests behave as neither hardening nor softing type. But CU triaxial tests behave as strain-hardening characteristics. Both CD and CU triaxial tests behave as non-linear and the linear interval is longer than the general clay.(2) After the sample yielding, the deviatoric stress σ1-σ3of CU triaxial tests level off faster than CD triaxial tests along with axial strain. If the sample strengh corresponds to the deviatoric stress of15-percent axial strain, the strengh of reticulate red clay under CD triaxial tests is higher obviously than that of CU triaxial tests. This phenomenon indicates that stress path has a significant effect on the stiffness strengh of remodeled reticulate red clay.(3) Parameters of Cambridge Model for remodeled reticulate red clay were determined by conventional triaxial tests and the correlation coefficient of linear fitting is very high. Different test methods have an effect slightly on the determination of parameter M. Stress path and history have an effect on the determination of parameter λ and nearly have no effect on parameter κ. The parameter λ determined by linear fitting of critical state line and normal consolidation line is different. (4) By comparing the measured values and calculated values of CD triaxial tests, the reliability and rationality of determined Parameters of Cambridge Model were attested. This provides reference values for the applying of Cambridge Model in reticulate red clay around Dongting Lake.(5) Parameters of Cambridge Model were determined by fall-cone tests. The results show that fall-cone test can be used to determine Parameters of modified Cambridge Model and provide reference values of modified Cambridge Model preliminarily.