Calculation of earth pressure based on disturbed state concept theory

The theoretical formulations of Coulomb and Rankine still remain as the fundamental approaches to the analysis of most gravity-type retaining wall,with the assumption that sufficient lateral yield will occur to mobilize fully limited conditions behind the wall.The effects of the magnitude of wall movements and different wall-movement modes are not taken into consideration.The disturbance of backfill is considered to be related to the wall movement under translation mode.On the basis of disturbed state concept(DSC),a general disturbance function was proposed which ranged from-1 to 1.The disturbance variables could be determined from the measured wall movements.A novel approach that related to disturbed degree and the mobilized internal frictional angle of the backfill was also derived.A calculation method benefited from Rankine's theory and the proposed approach was established to predict the magnitude and distribution of earth pressure from the cohesionless backfill under translation mode.The predicted results,including the magnitude and distribution of earth pressure,show good agreement with those of the model test and the finite element method.In addition,the disturbance parameter b was also discussed.

Mesoscopic analysis of the utilization of hardening model for a description of softening behavior based on disturbed state concept theory

Mesoscopic characteristics of a clayey soil specimen subjected to macroscopic loading are examined using a medi- cal-use computerized tomography (CT) instrument. Disturbed state concept (DSC) theory is based on the utilization of the hard- ening model. DSC indirectly describes material behavior by claiming that the actual response of the material is expressed in terms of the relative intact (RI) response and the fully adjusted (FA) response. The occurrence of mesoscopic structural changes of material has similarities with the occurrence of a macroscopic response of the material under loadings. In general, the relative changing value of a softening material is three to five times more than that of a hardening material. Whether special zones exist or not in a specimen cross section does not affect the following conclusion: hardening material and softening material show me- chanical differences with CT statistical indices values prominently changing, and the change is related to the superposing of a disturbance factor. A new disturbance factor evolution function is proposed. Thus, mesoscopic statistical indices are introduced to describe macroscopic behavior through the new evolution function. An application of the new evolution function proves the effectiveness of the amalgamation of a macroscopic and a mesoscopic experimental phenomenon measurement methods.

Disturbed state concept as unified constitutive modeling approach

A unified constitutive modeling approach is highly desirable to characterize a wide range of engineeringmaterials subjected simultaneously to the effect of a number of factors such as elastic, plastic and creepdeformations, stress path, volume change, microcracking leading to fracture, failure and softening,stiffening, and mechanical and environmental forces. There are hardly available such unified models. Thedisturbed state concept （DSC） is considered to be a unified approach and is able to provide materialcharacterization for almost all of the above factors. This paper presents a description of the DSC, andstatements for determination of parameters based on triaxial, multiaxial and interface tests. Statementsof DSC and validation at the specimen level and at the boundary value problem levels are also presented.An extensive list of publications by the author and others is provided at the end. The DSC is considered tobe a unique and versatile procedure for modeling behaviors of engineering materials and interfaces. 2016 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. This is an open access article under the CC BY-NC-ND license

Development of a constitutive model for rockfills and similar granular materials based on the disturbed state concept

Behavior of rockfills was investigated experimentally and theoretically.A series of standard triaxial compression tests were carried out on a quarried rockfill material at different stress levels.It was found that both the stress level and the shear stress ratio,like most of granular materials,controls the behavior of rockfill materials.At lower shear stress ratios the behavior is much more similar to a nonlinear elastic solid.When the shear stress goes further,the stressstrain curve shows an elasto-plastic behavior which suggests using the disturbed state concept to develop a constitutive model to predict the stress-strain behavior.The presented constitutive model complies reasonably with the experimental data.

Testing and modeling of frozen clay-concrete interface behavior based on large-scale shear tests

The shear behavior of the frozen soil-structure interface is important for accurately predicting the interface responses of structures adopted in the cold regions.The purpose of this study is to experimentally and theoretically investigate the shear behavior of frozen clay-concrete interface under engineering conditions.A large-scale direct shear apparatus with a temperature-controlled shear box is used to test the interface behavior.Test specimens consisting of a cement concrete block and frozen soil with initial water content ranging between 14.6%and 24.6%were prepared at different conditions of temperatures(15.4 to-9.8℃),shear rates(0.03-0.9 mm min^(-1)),and normal stresses(50-200 kPaj.It is found that the peak shear strength is linear developing with increasing of normal stress,initial water content,and temperature.It increased from 67.7 to 133.3 kPa as the initial water content increased from 14.9%to 24.6%at temperature of-6.8 to-6.6℃,and it increased from 51.2 to 80.6 kPa with temperature decreasing from 15.4 to-9.8℃at initial water content of 14.6%-14.9%,furthermore it has a power law relationship with shear rate.The final vertical displacement increases with the decreasing temperature,and increasing initial water content.While,it is slight or could be ignored at lower shear rates(e.g.0.03 mm min^(-1) and 0.15 mm min^(-1))and it is-0.25 mm and-0.28 mm at shear rate of 0.3 mm min^(-1) and 0.9 mm min^(-1),respectively.In addition,the evolution of vertical displacement also varies with test condition,the growth rate at beginning increases with increasing initial water content and decreasing temperature or ice content,which is because of the ice film effects the particle size.Moreover,a disturbed state concept model combined with linear and nonlinear characteristics is developed to describe the interface shear behavior.The disturbance D reflects the interface mechanical response and responds differently trend for different test conditions,increasing faster with increasing temperature and decreasing initial water content or shear rate.The testing results,including the test and model results,can be used to simulate the performance of engineered geotechnical assets such as earth dams or irrigation channels with concrete linings in cold regions.

Macroscopic and Mesoscopic Parameters Introduction into Stress-Strain Relationship Description of Clayey Soils

Disturbed state concept(DSC) theory maintains that the observed actual response(AR) of material under loading effects is composed of and determined by two reference state responses,namely relative intact(RI) state response and fully adjusted(FA) state response. Hardening material shows macroscopic behavior characteristics of RI response and shows negligible mesoscopic structure changes. Pore water pressure dissipation in macroscopic experiment or variance of computerized tomography(CT) value in mesoscopic experiment,as chosen characteristic parameters,can be introduced to the evolution function of disturbance factor to revise response of hardening to be response of softening. RI behavior is constituted via using hardening model. The characteristic parameters are extracted from regulations which exist in macroscopic or mesoscopic experimental data of softening material. DSC approach strategy on response prediction is presented through the combination of characteristic parameters and hardening constitutive model within the procedure of softening response prediction.