Prediction of permanent deformation for subgrade soils under traffic loading in Southern China
TL;DR: In this paper, the cumulative permanent strain of subgrade soils plays an important role in the pavement structure design and long-term pavement performance maintenance in Southern China, the hot and humid clima...
Abstract: The cumulative permanent strain of subgrade soils plays an important role in the pavement structure design and long-term pavement performance maintenance. In Southern China, the hot and humid clima...
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TL;DR: In this paper, the variation law of the dynamic resilient modulus of C&D waste under repeated freeze-thaw cycles was revealed and a reasonable performance prediction model was established.
49 citations
TL;DR: In this paper, the coupling steady-state vibration of an impermeable, rigid, circular plate resting on a finite, fluid-saturated, poroelastic soil layer underlain by rigid base and subjected to a vertical time-harmonic loading is studied.
Abstract: Studies associated with dynamic plate–medium interactions generally assumed the plate structures to be permeable for the sake of convenience. But the effect and applicability of such an assumption are still unclear, and then the pore fluid pressure on the plate and medium interfaces cannot be obtained. In this paper, the mentioned problems are discussed by studying the coupling steady-state vibration of an impermeable, rigid, circular plate resting on a finite, fluid-saturated, poroelastic soil layer underlain by rigid base and subjected to a vertical time-harmonic loading. The semi-analytical solutions for the dynamic compliance, displacements, stresses, especially the contact stress including effective stress and pore fluid pressure of the plate and the layer, are proposed. In developing these solutions, the linearly poroelastic model established by de Boer is used to describe the mechanical behaviour of the porous medium. By means of four scalar displacement potentials and the Fourier–Hankel transformation to solve the equations of motion of the poroelastic layer, and then imposing boundary and interfacial conditions, a pair of coupling Fredholm’s integral equations of the second kind formulating the plate–medium interaction are derived and evaluated with numerical methods. The proposed solutions are then verified by comparing with the existing special solutions and the FEM calculation results. Numerical examples are also performed to examine the effects of the permeability of both the plate and the poroelastic layer and the thickness of the layer on the dynamic response of the coupling system.
45 citations
TL;DR: Wang et al. as mentioned in this paper determined the moisture contents of unsaturated clay embankments in southern China considering the stress state, and 6 frequency domain reflectometry sensors were installed in a widened embankment to monitor the moisture content.
Abstract: To determine the moisture contents of unsaturated clay embankments in southern China considering the stress state, 753 moisture data of three existing embankments for about 20 years were measured, and six frequency domain reflectometry sensors were installed in a widened embankment in southern China to monitor the moisture content. The soil water characteristic curve (SWCC) and stress-dependent soil water characteristic curves (SDSWCCs) were determined in the laboratory using a pressure plate apparatus and a stress-dependent parametric equation was established. The finite element model of a typical unsaturated clay embankment in southern China considering the SWCC and SDSWCCs was created. Then, the variation of the moisture contents of the clay embankment was simulated. The results show that the vertical stress has an obvious effect on the moisture distribution in embankments, especially the positions inside embankments where the vertical stress is large and cannot be neglected. The finite element model considering the SDSWCCs, therefore, should be selected when analyzing the moisture filed of embankments in southern China. For the existing clay embankments in southern China, their moisture contents gradually increase from the optimum moisture content to equilibrium values, which is close to the plastic limit and increases by 99% of the optimum moisture content. In addition, the resilient modulus values at different locations of the embankment and that of the whole embankment are reduced by 55 to 62%. And the safety factor of the slope obviously decreases, and its reduction is greater than 60%.
36 citations
Cites background from "Prediction of permanent deformation..."
...The embankment is the basis of the road structure, and the moisture content affects the performance of the embankment (Peng et al. 2020; Zhang et al. 2020b)....
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...Compacted soils are frequently used as engineering fills for the construction of expressway embankments, and the fills are often compacted in an unsaturated state (Abu-Farsakh et al. 2015; Ng and Leung 2012; Zhang et al. 2020a)....
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TL;DR: Wang et al. as mentioned in this paper presented an experimental investigation on the performance of cement stabilized recycled mixture containing recycled concrete aggregate (RCA) and crushed brick (RCB), which are separated from recycled aggregate.
24 citations
TL;DR: In this article , the influence of the aggregate morphology on deformation behavior of unbound granular materials (UGMs) based on a real aggregate library and the discrete element method was investigated.
Abstract: The Monte Carlo simulation (MCS) has been developed to estimate the strength distributions of heterogeneous materials influenced by different factors. The method presents a statistical correlation between the macroscopic properties and the non-uniform characteristics at meso scale. This study proposes an extensive MCS to investigate the influence of the aggregate morphology on deformation behaviour of unbound granular materials (UGMs) based on a real aggregate library and the discrete element method. Two indexes, elongation index (EI) and flatness index (FI), were used to evaluate the morphological characteristics of 3D aggregates rebuilt by the X-ray CT technique. Furthermore, repeated load triaxial tests of UGMs were simulated by 50 MCS samples. The effects of shapes and sizes of aggregates on deformation behaviours were statistically analysed. The results show that the deformation behaviour is dependent on the size and the EI distribution, but insensitive to the loading frequencies and FI distribution.
23 citations
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Journal Article•
TL;DR: In this article, the authors examined various procedures for controlling or estimating the contribution of the subgrade to the total permanent deformation that occurs in the pavement structure as a result of repeated traffic loads.
Abstract: Various procedures are examined for controlling or estimating the contribution of the subgrade to the total permanent deformation that occurs in the pavement structure as a result of repeated traffic loads. The use of layered elastic analysis to estimate the vertical compressive strain at the subgrade surface is suggested as one procedure to control such deformation. A summary of available strain data is included. If these criteria are used for design purposes, the same range in stiffness for the asphalt-bound layer and the same values of Poisson's ration must be used as were used to develop the criteria. Layered elastic analysis is also suggested for estimating the amount of permanent deformation caused by the subgrade. This analysis is based on relationships among permanent strain, applied stress, and number of stress applications based on repeated-load triaxial compression tests; and these relationships are discussed. Data also indicate the importance of stress history effects. Time hardening and strain hardening permit estimates of cumulative loading effects from the results of tests at single stress levels. Although neither method predicts precisely the accumulation of permanent strain under different stress sequences, both bound the measured data and therefore have the potential to assist in the estimation deformation or rutting from cumulative traffic loading.
330 citations
01 Sep 1972
TL;DR: In this article, the authors used the repeated load triaxial test to evaluate the relative performance of unstabilized base course materials with respect to rutting and then used in the evaluation of a number of materials.
Abstract: A method is presented for evaluating the relative performance of unstabilized base course materials with respect to rutting and is then used in the evaluation of a number of materials. A general method is also proposed for calcualting rut depth occurring in flexible pavements. The proposed methods make use of the plastic axial strains obtained from the repeated load triaxial test. Cylindrical specimens 6 in. in diameter and 12 in. in height of crushed stone and soil-aggregate mixtures were placed in a conventional triaxial cell and subjected to 100,000 load repetitions using a constant confining pressure and a triangular stress pulse. Stress-strain curves giving the relationship between deviator stress, confining pressure and plastic axial strain were constructed for each material studied using the repeated load test results. The concept of a rut index was proposed which can be calculated making use of the plastic stress-strain relationship, and is approximately proportional to the rut depth that will occur in the base after a desired number of load repetitions. The rut index appears to offer a practical laboratory method for evaluating the relative performance of base materials used in pavements having similar structural configurations. An evaluation of the test results using the rut index approach indicates that under good conditions of drainage and proper maintenance of the pavement surface, carefully selected blends of 20 percent soil and 80 percent stone should perform satisfactorily. Soil aggregate blends having properties similar to the materials tested should probably not be used at all under poor drainage conditions, and 40-60 blends should not be used even under good conditions of drainage. The results further indicate that only a sufficient amount of fines should be used in a crushed stone base to permit proper compaction if the amount of rutting in the base is to be minimized. Furthermore, even though the specified gradation and density may be the same, bases constructed from aggregates obtained from different sources may exhibit different rutting characteristics. A general engineering method for estimating the rut depth in a flexible pavement after a desired number of load repetitions was proposed which utilizes nonlinear layered theory, the plastic stress-strain response of the component materials, and a hyperbolic, plastic stress-strain law. Field verification is now needed of both the proposed rut index and the general method for predicting rut depth. /Author/
292 citations
"Prediction of permanent deformation..." refers methods in this paper
...In the subsequent research, the formula semi-logarithmic model was proposed (Barksdale 1972)....
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01 Jan 1989
TL;DR: In this paper, a method to predict the permanent deformation (rutting) in pavements using a mechanistic-empirical model of material characterization is presented, and the results are used in the prediction of the loss of serviceability index of pavements.
Abstract: This paper presents a method to predict the permanent deformation (rutting) in pavements using a mechanistic-empirical model of material characterization. Three permanent deformation parameters are developed through material testing to simply represent the curved relationship between permanent strains and the number of load cycles. Equations are developed by regression analysis which determine how these three parameters are affected by the material properties, environmental conditions (moisture and temperature), and stress state. These relations are important in calculating the permanent deformation of pavement layers since the relation between permanent deformation and cycles of load from the laboratory is usually examined in test conditions that are significantly different from field conditions. The permanent deformations calculated from the method presented are compared with results measured in the field in Florida and are found to be accurate. The permanent deformation obtained is shown to be in reasonable agreement with the measured results. It is demonstrated that this method provides an appropriate and realistic analysis of prediction of the permanent deformation, and further, the results are used in the prediction of the loss of serviceability index of pavements using the American Association of State Highway and Transportation Officials (AASHTO) Road Test relation. The paper demonstrates the importance of accurate materials characterization in predicting the rutting of asphalt concrete pavements on granular base course. (A) For the covering abstract see IRRD 862156.
175 citations
"Prediction of permanent deformation..." refers background in this paper
...Category A Tseng and Lytton (1989) proposed the following equation, as shown in Equation (3), which relates the permanent deformation of the pavement to the elastic strain of subgrade, aggregate and asphalt materials....
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TL;DR: In this paper, the specification of the resilient modulus for each soil subgrade encountered in the pavement project is discussed and a method for flexible pavement design is proposed, which is based on the concept of flexible pavement.
Abstract: Mechanistic design methods for flexible pavement require the specification of the resilient modulus Mr for each soil subgrade encountered in the pavement project. The resilient modulus is usually m...
170 citations
TL;DR: Wang et al. as mentioned in this paper analyzed the physical and chemical properties of construction and demolition wastes (CDW) subgrade construction case in Beijing, and a series of tests (compaction degree test, settlement observation, Portable Falling Weight Deflectometer test) were carried out.
123 citations
"Prediction of permanent deformation..." refers background in this paper
...Meanwhile, through field measurements, it proves that the permanent deformationof subgrade cannot be ignored (Gao et al. 2018, Zhang et al. 2020)....
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