Experimental Study On Triaxial Creep And Dynamic Characteristics Of Compacted Red Clay In Anning Refinery

Red clay is a brown or tawny high plasticity viscous soil formed by weathering of carbonate salts,such as limestone and dolomite,in hot and humid conditions.Because of its good mechanical properties,it is widely considered as the ideal natural roadbed and good building material in engineering.At the same time,it has the safety potential because of its crack,expansion and typical regional differences.This paper takes the filling red clay in the factory of Anning Refinery of Petro China Yunnan Petrochemical as the object of study.A series of indoor static and dynamic triaxial tests were carried out on compacted red clay,and the creep characteristics and dynamic characteristics of compacted red clay under long-term loads and cyclic loads were studied.The research results are as follows:1.The triaxial creep test of compacted red clay with different confining pressure,different eccentric stress level and different drainage conditions was carried out by using the SLB-1 type stress-strain controlled triaxial shear permeation instrument.The stress-strain isochronal curves and strain-time curves of compacted red clay were obtained by means of Chen’s method.Research shows that:The compacted red clay is nonlinear attenuation creep,Under the condition of low stress level,the creep deformation value is greater than undrained creep,With the development of time,when the stress level is greater than a certain value,the creep deformation under undrained condition is greater than that of the drainage creep deformation.Under undrained conditions,the creep change of compacted red clay is more obvious than that under drainage.In addition to the initial moment of stress-strain,the other curves formed a curve cluster with the phenomenon of "normalization".2.Based on the stress-strain curve and the strain-time curve obtained by triaxial creep test,the parameters of Burgers element model are identified,and through the analysis of the curve of the change and development trend found that,The hyperbolic curve can describe the creep function better,the exponential function can describe deformation function better,And the empirical creep model is established.By comparison,it is proved that this empirical model can better describe the creep properties of compacted red clay in this area.Compared with the Burgers component model,the accuracy is higher,the parameters are easier to obtain.3.Based on the GDS dynamic triaxial apparatus,dynamic strength test and dynamic modulus test of a series of pure pressure cyclic loads are carried out.The influence of different confining pressure,over-consolidation ratio and dynamic stress amplitude on dynamic characteristics of red clay was analyzed emphatically.The test results show that:The critical dynamic stress of compacted red clay is proportional to the over-consolidation ratio and confining pressure,and the linear relation is satisfied.The axial cumulative strain with dynamic stress is worth increasing the development trend of stable type and destructive type.The internal friction angle increases with the increase of the over-consolidation ratio,Moreover,the larger the over-consolidation ratio,the less obvious the effect of the vibration.The influence of vibration times on the dynamic cohesion of the over-consolidated red clay is great,and the effect on the internal friction angle is small.Both of them show a linear downward trend.The dynamic modulus of elasticity increases with the increase of confining pressure and over-consolidation ratio.it decreases as the dynamic strain increases.The corresponding maximum dynamic modulus of elasticity increases linearly with the increase of confining pressure and over-consolidation ratio.The empirical formula for the maximum dynamic elastic modulus of compacted red clay in this area is obtained by multivariate linear regression analysis.