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Journal ArticleDOI: 10.1080/14680629.2019.1651756

Predicting resilient modulus of fine-grained subgrade soils considering relative compaction and matric suction

04 Mar 2021-Road Materials and Pavement Design (Informa UK Limited)-Vol. 22, Iss: 3, pp 703-715
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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Topics: Suction (51%)

46 results found

Journal ArticleDOI: 10.1016/J.JCLEPRO.2020.120223
Junhui Zhang1, Le Ding1, Li Feng1, Junhui Peng1Institutions (1)
Abstract: With the rapid advancement of urbanization in China, a huge amount of construction and demolition wastes (CDW) are generated. Recycling CDW into subgrade materials is a promising way to process these wastes, with significant environmental and economic benefits. But very little work has been done in this field. Therefore, based on a CDW subgrade construction case in Beijing, the physical and chemical properties of the CDW materials were analyzed. Then the construction procedures of the CDW subgrade were presented, and a series of tests (compaction degree test, settlement observation, Portable Falling Weight Deflectometer test) were carried out. At the same time, the effects of different loose paving thicknesses, cycles of strong vibration on the subgrade performances were assayed. Subsequently, grading analysis of the CDW particles, plate load test and Beckman beam deflection test were performed to evaluate the construction quality. According to the test results, the construction technologies of the CDW subgrade, such as the optimum loose paving thicknesses and cycles of strong vibration, were determined. And then, the post-construction settlement monitor and radar survey were conducted for subgrades filled with CDW and soil to further analyze the applicability of CDW. The results show that recycled CDW aggregates with proper grading and strict construction technologies perform well. The subgrade filled with recycled CDW has a smaller deformation than that of the soil subgrade. Finally, the life cycle assessments (LCA) of two treating schemes of CDW were conducted to analyze the environmental benifits: recycling utilization as subgrade materials and directly landfilling. If the subgrade is filled with the recycled CDW aggregates, CDW will be consumed in large quantities and the environmental impactions of eutrophication and ecotoxicity can be reduced obviously.

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Topics: Subgrade (59%)

63 Citations

Open accessJournal ArticleDOI: 10.1016/J.COMPGEO.2019.103413
Junhui Peng1, Junhui Zhang1, Jue Li1, Yongsheng Yao2  +1 moreInstitutions (2)
Abstract: This study aimed to develop a finite element model to simulate the flexible pavement structure by considering the nonlinear characteristics of subgrade soils which are related to humidity and stress. First, an analytical model was proposed and proven to quantify the effect of the humidity and stress on the resilient modulus of subgrade soils. Second, a UMAT was programmed to characterize nonlinear moisture and stress-sensitive relationship of subgrade soils. Then, the humidity field values of subgrade were calculated by GEOSTUDIO and verified by field measurement. Meanwhile, the humidity field values were imported into ABAQUS through MATLAB. Finally, the UMAT was implemented in the finite element model of flexible pavement structures. The finite element simulation indicated that the distribution of moisture content of subgrade significantly affects the resilient modulus distribution of subgrade and critical response of pavement structures. Resilient modulus of subgrade soils in the vicinity of load area are significantly larger than those far away the load area. The surface deflection, the tensile stress at the bottom of inorganic binder base, and the compressive strains on the top of subgrade increase greatly with the initial humidity field condition to the equilibrium humidity field condition.

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Topics: Subgrade (68%)

36 Citations

Journal ArticleDOI: 10.1080/10298436.2020.1765244
Junhui Zhang1, Junhui Peng1, Anshun Zhang1, Jue Li1Institutions (1)
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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24 Citations

Journal ArticleDOI: 10.1007/S10064-020-01916-6
Junhui Zhang1, Li Feng1, Ling Zeng1, Junhui Peng1  +1 moreInstitutions (1)
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%.

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Topics: Moisture (56%), Water content (51%)

20 Citations

Journal ArticleDOI: 10.1016/J.JCLEPRO.2021.126702
Junhui Zhang1, Anshun Zhang1, Huang Chao1, Huayang Yu2  +2 moreInstitutions (3)
Abstract: Recycling construction and demolition (C&D) waste as fillers in pavement subgrade is a sustainable paving technology with environmental and economic merits. The performance of pavement subgrade with C&D waste depends on its dynamic resilient modulus. Meanwhile, freeze–thaw cycles are also an important issue for engineering in seasonal frozen regions. However, research on characteristics of the dynamic resilient modulus of C&D waste, especially the properties under freeze–thaw cycles, is limited. To this end, this study aims to reveal the variation law of the dynamic resilient modulus of C&D waste under repeated freeze–thaw cycles and establish a reasonable performance prediction model. This study conducts a series of laboratory tests after various freeze–thaw cycles. Results indicate that the soil–water characteristic curves of C&D waste with different compactness and number of freeze–thaw cycles can be well described by Van Genuchten’s model. Moreover, the dynamic resilient modulus enhances with the increase of matric suction, compactness, deviator stress and minimum bulk stress and exhibits a stress-hardening characteristic. Freeze–thaw cycles attenuate the matric suction and dynamic resilient modulus of C&D waste. Besides, high moisture contents, low stress levels and more freeze–thaw cycles all aggravate the attenuation of the dynamic resilient modulus in certain extent, but the attenuation is not sensitive to the compactness. Finally, this study establishes a high-accuracy prediction model of the dynamic resilient modulus considering the effect of repeated freeze–thaw cycles. This study can supply useful information on the application of C&D waste in pavement subgrade in seasonal frozen regions.

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Topics: Subgrade (53%)

14 Citations


23 results found

Journal ArticleDOI: 10.1139/T94-061
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.

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Topics: Curve fitting (67%), Soil mechanics (54%), Water content (50%)

2,278 Citations

Journal ArticleDOI: 10.1680/GEOT.2000.50.5.487
28 Mar 2000-Geotechnique
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...

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Topics: Stiffness (52%)

314 Citations

Open accessJournal ArticleDOI: 10.1680/GEOT.1996.46.3.383
01 Sep 1996-Geotechnique
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 ...

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287 Citations

Journal ArticleDOI: 10.1080/14680629.2011.9695263
Carlos E. Cary1, Claudia E. Zapata1Institutions (1)
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.

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Topics: Modulus (51%)

129 Citations

Journal ArticleDOI: 10.1061/(ASCE)0733-947X(2008)134:1(34)
Abstract: The resilient modulus of the materials used in various pavement layers has been used extensively as an important material property in structural design of pavement. The state of stress and moisture content of cohesive soils have been observed to exert significant effects on the measured resilient modulus. Since the moisture content in the cohesive subgrade soils underneath the pavement undergoes seasonal changes due to infiltration of precipitations and since characterization of moisture and stress dependent resilient modulus of cohesive soils is a demanding and tedious task, there is a practical need for a predictive equation for the resilient modulus as a function of stress states and moisture content. This paper presents a new predictive equation for the resilient modulus of cohesive soils using the concept of soil suction. The accuracy of the proposed model is validated against experimental data of A-4 and A-6 soils conducted by the writers as well as by other data available in the literature. The proposed model provides advantages over the existing predictive equations by reducing the number of tests and soil specimens needed for determining the regression coefficients in the equation. The proposed predictive equation compares well with the empirical equation in the new mechanistic empirical pavement design guide (MEPDG) in predicting the effect of moisture content variation on the resilient modulus. The proposed model provides an advantage over the MEPDG empirical equation in taking into account the effects of both the stress state and moisture content on the resilient modulus of cohesive soils.

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105 Citations