Predicting resilient modulus of fine-grained subgrade soils considering relative compaction and matric suction
TL;DR: In this article, the resilient modulus has been used to characterise the stress-strain nonlinear behaviour of subgrade soils and is an important parameter for pavement design and analysis, which aims at devel...
Abstract: The resilient modulus has been used to characterise the stress-strain non-linear behaviour of subgrade soils and is an important parameter for pavement design and analysis. This study aims at devel...
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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
TL;DR: In this paper, a finite element model was developed to simulate the flexible pavement structure by considering the nonlinear characteristics of subgrade soils which are related to humidity and stress, and a UMAT was programmed to characterize nonlinear moisture and stress-sensitive relationship of sub grade soils.
51 citations
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 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...
39 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 or methods from "Predicting resilient modulus of fin..."
...This usually results in a reduction in the soil shear strength (Han and Vanapalli 2017; Hatami et al. 2016) and embankment bearing capacity (Ng et al. 2013; Zhang et al. 2019a) and a continuous increase in the permanent deformation of embankments (Khoury et al. 2012; Salour and Erlingsson 2017)....
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...Considering the influence of moisture content and stress state on resilient modulus, Zhang et al. (2019b) proposed a prediction model: MR ¼ k0pa ln ψ pa þ e þ k1 θm pa k2 τoct pa þ 1 k3 ð8Þ where MR is the resilient modulus; ψ is the soil suction; θm is the minimum bulk stress under certain stress…...
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TL;DR: In this paper, a nonlinear, least squares computer program is used to determine the best-fit parameters for experimental data presented in the literature, based on the assumption that the shape of the soil-water characteristic curve is dependent upon the pore-size distribution.
Abstract: The soil-water characteristic curve can be used to estimate various parameters used to describe unsaturated soil behaviour. A general equation for the soil-water characteristic curve is proposed. A nonlinear, least-squares computer program is used to determine the best-fit parameters for experimental data presented in the literature. The equation is based on the assumption that the shape of the soil-water characteristic curve is dependent upon the pore-size distribution of the soil (i.e., the desaturation is a function of the pore-size distribution). The equation has the form of an integrated frequency distribution curve. The equation provides a good fit for sand, silt, and clay soils over the entire suction range from 0 to 106 kPa. Key words : soil-water characteristic curve, pore-size distribution, nonlinear curve fitting, soil suction, water content.
2,644 citations
TL;DR: In this paper, a back-analyses of the load settlement behavior of full-scale and model foundations demonstrate the influence of non-linear soil stress-strain behaviour on load settlement.
Abstract: Soil stress-strain behaviour is highly non-linear and this has an important influence on the selection of design parameters for simple routine geotechnical calculations. Non-linear behaviour can be characterized by rigidity and degree of non-linearity and these can be determined from measurements of very small strain-stiffness, peak strength and failure strain. Very small strain-stiffness can be found from measurements of shear wave velocity in situ or in laboratory tests. Peak strength and failure strain can be measured in routine laboratory tests but are strongly influenced by initiation of shear bands. The important non-linear stiffness parameters for soil are related to its composition and to its current state. Back-analyses of the load settlement behaviour of full-scale and model foundations demonstrate the influence of non-linear soil behaviour. Variations of stiffness with settlement calculated from full-scale and model foundations agree well with non-linear soil stiffnesses based on rigidity and d...
360 citations
TL;DR: In this paper, the authors apply the principles of soil mechanics to the design of pavement foundations, and apply this knowledge to pavement design with the aid of appropriate theoretical analysis and an understanding of failure mechanisms.
Abstract: Application of soil mechanics principles to the design of pavement foundations, the design of complete pavements and to their structural evaluation'in-service' has lagged some way behind knowledge accumulated through research. Present design methods are generally empirical and often based on use of the California Bearing Ratio test, which was abandoned in California some fifty years ago. The soil mechanics problem is one of understanding how soils and granular materials respond to repeated loading and applying this knowledge to pavement design with the aid of appropriate theoretical analysis and an understanding of failure mechanisms. Non-linear stress-strain characteristics are a particular feature of the problem and have to be catered for in design and evaluation. Various ‘tools’ are available to assist the pavement engineer. These include theoretical analysis, laboratory testing apparatus, field testing and full-scale trials with appropriate instrumentation. The resilient and permanent strain response ...
321 citations
TL;DR: In this paper, the suitability of the current resilient modulus test protocol (NCHRP 1-28A) for its application to unsaturated soils was assessed, and the results allowed for the enhancement of the Universal Model for resilient Modulus prediction by incorporating suction as a stress state.
Abstract: The suitability of the current resilient modulus test protocol (NCHRP 1-28A) for its application to unsaturated soils was assessed. Modifications to the stress state conditions of the protocol are necessary due to the axis-translation needed during the test when measuring matrix suction. This study presents the modulus of unbound materials resulting from tests performed under unsaturated soil conditions. Two different materials were tested. The base material was tested under drained and undrained boundary conditions, while the subgrade was tested under drained boundary condition. The results allowed for the enhancement of the Universal Model for resilient modulus prediction by incorporating suction as a stress state. This model predicts the resilient response of unbound materials as a function of external stress state and matrix suction levels and therefore, it is independent of moisture variation.
145 citations
TL;DR: The shear modulus at very small strains (0·001% or less), G0, is one of the most important parameters for predicting ground movements and dynamic responses of many engineering earth structures as mentioned in this paper.
Abstract: The shear modulus at very small strains (0·001% or less), G0, is one of the most important parameters for predicting ground movements and dynamic responses of many engineering earth structures Wit
118 citations