Study On Dynamic Constitutive Relationship And Dynamic Characteristics Of Red Clay In Guiyang Area

As a typical type of special soil,red clay shows high water content,high plasticity,high porosity ratio,low density and poor compaction.It is mainly distributed in Guizhou,Guangxi,Yunnan and Hunan provinces.The engineering application is very extensive,and its mechanical properties have a great influence on the design and construction of the project.Based on the existing research,this paper takes the original red clay in Guiyang area as the research object,combines its regionality and particularity,and uses the indoor experimental and theoretical analysis methods to study the basic physical indexes and static forces of the original red clay in Guiyang area.The characteristics and dynamic characteristics,fatigue characteristics,determination of critical dynamic stress of undisturbed red clay and dynamic constitutive relations have been systematically studied.The main research work is as follows:?1?Based on the routine geotechnical test in the room,the basic physical index test,consolidation tests and CU triaxial test were carried out on the primary red clay sample.The basic physical indicators of the primary red clay,such as water content,natural density,specific gravity,liquid plastic limit and void ratio compression modulus and compression factor,were obtained.The law of change of the failure mode,stress-strain relationship curve,pore water pressure-axial strain relationship curve of the primary red clay sample and the shear strength index of red clay under different water content and different confining pressure,according to the results of CU triaxial test,are analyzed.?2?Through the dynamic shear modulus and damping ratio triaxial test,the dynamic stress-dynamic strain relationship of the original red clay in Guiyang under different experimental conditions was studied.The?_d^?_d relationship curve and G/G_max^?_d of the original red clay were obtained.The change law of G/G_max^?_d and?^?_d relationship curves.The Hardin-Drnevich hyperbolic model was used to fit the experimental data to obtain the G/G_max^?_d and?^?_d empirical curves of the original red clay of Guiyang.The test parameters of the dynamic shear modulus and damping ratio and the maximum dynamic modulus G_maxax and maximum?_maxax were obtained.The factors affecting the damping ratio max are analyzed.?3?The relationship between the cumulative plastic strain?_p and the number of fatigue load N of Guiyang primary red clay is obtained through the fatigue triaxial test,which shows non-linearity.The analysis of the test results shows:the types of the?_p^lgN relationship curves are“stable”,“critical”and“destructive”in order;The variation range and average value of the critical dynamic stress?_dcc of the primary red clay in Guiyang under the test conditions of 35 kPa,45 kPa and 55 kPa were obtained;it provides a certain reference for the engineering application of red clay dynamic stability by analyzing the law of change of?_p^lgN relationship curve and the critical dynamic stress?_dc.?4?Based on the fatigue test results,based on the variation law of?_p^lgN relationship curve,starting from the basic mechanical components such as elastic components and viscous components,the fractional calculus function is introduced to improve the Maxwell model and the Abel stick.The theory deduces two kinds of energy.Describe the theoretical expression of the fatigue constitutive relation of the original red clay.Considering the influence of expression parameters,the rationality of the modified Abel cohesive constitutive relation is verified according to the experimental data.The relevant parameters of the model are given and their applicability is discussed.The research work can provide new ideas for the study of the dynamic characteristics and dynamic constitutive relations of the original red clay in Guizhou area.It has certain reference value and practical significance,and lays a solid experimental and theoretical basis for the next research work in related fields.